WO2023235376A1

WO2023235376A1 - Process for preparing 1-(4-chlorobenzyl)-1h-imidazole-4,5-dicarboxamide

Info

Publication number: WO2023235376A1
Application number: PCT/US2023/023965
Authority: WO
Inventors: Daniel Walker; Calin SFERDEAN; Matthew Joseph Birchmeier; Tapan MAJI
Original assignee: Zoetis Services Llc
Priority date: 2022-06-01
Filing date: 2023-05-31
Publication date: 2023-12-07

Abstract

The present application provides a process for preparing the anticoccidial benzyl imidazole, l-(4-chlorobenzyl)-l H-imidazole-4,5- dicarboxamide (Formula 1) from l-(4-chlorobenzyl)-l H-imidazole-4,5-dicarbonitrile, that is prepared by reacting a solution of diaminomaleonitrile, a glycol ether and formic acid.

Description

PROCESS FOR PREPARING

1 -(4-CHLOROBENZYL)-1 H-IMIDAZOLE-4,5-DICARBOXAMIDE

FIELD OF THE INVENTION

The present invention describes a new process for preparing the anticoccidial benzyl imidazole of Formula (1 ), 1-(4-chlorobenzyl)-1 H-imidazole-4,5-dicarboxamide from diaminomaleonitrile.

BACKGROUND OF THE INVENTION

Coccidiosis, which is caused by Eimeria spp protozoa, is a major animal parasitic disease that causes significant losses in livestock. Chicken coccidiosis alone can cause global losses of up to 4 billion US dollars annually. Coccidiosis is also recognized as a pathogen in other species of livestock, including swine, cattle, goats and sheep. Each type of coccidia infects only one species of livestock, each is species-specific. There are seven different Eimeria species that infect chickens, but only three cause most of the trouble in the USA and include: E. tenella, E. maxima and E. acervulina. Immunity to one type does not provide immunity for other types. Turkeys, ducks, geese, and other types of poultry are all infected by different species of coccidia. Damage is incurred by the rapid multiplication of the parasite in, and the subsequent rupture of cells of the intestinal lining. At present, control of animal coccidiosis relies mainly on anticoccidial agents (e.g., amprolium, decoquinate, lasalocid, monensin, nicarbazin and others). However, the long-term and widespread use of them has led to an increased incidence of resistance. There is a need for a new and effective synthetic anticoccidial agent, for example, 1 -(4-chlorobenzyl)-1 H-imidazole-4,5-dicarboxamide, which is useful for reducing and/or eliminating the parasitic burden to livestock, particularly poultry; and to combat resistance.

The anticoccidial agent, 1-(4-chlorobenzyl)-1 H-imidazole-4,5-dicarboxamide, Formula (1 ), and methods of synthesis were described in US Patent No. 10,435,376 B2 (hereinafter US‘376), which processes afforded a yield of only 44%. Imidazole derivatives have also been prepared using similar methods (US Patent No. 4,185,992). In this earlier ‘992 patent, the process described a 2-step preparation of 1-(4- chlorobenzyl)-4,5-dicyanoimidazole from diaminomaleonitrile. Condensation of diaminomaleonitrile with triethylorthoformate in anisole (US Patent No. 2,534,331 ), followed by subsequent treatment with sodium hydride and 4-chlorobenzyl chloride in dimethyl formamide afforded 1 -(4-chlorobenzyl)-4,5-dicyanoimidazole in 42% overall yield. The process utilizes sodium hydride which carries an explosion hazard (see: Yang et al. Org. Proc. Res. Dev. 2019, 23, 2210) in combination with DMF. DMF is an expensive solvent that is difficult to re-use in subsequent syntheses. Thus, alternate routes for preparing 1-(4-chlorobenzyl)-1 H-imidazole-4,5-dicarboxamide that avoid dangerous reagents and allow for a more efficient and cost effective synthetic route are highly desirable.

SUMMARY OF THE INVENTION

In one aspect of the invention, is a new process for preparing the intermediate 1- (4-chlorobenzyl)-1 H-imidazole-4,5-dicarbonitrile from diaminomaleonitrile (DAMN) and subsequent reactions to prepare the Formula (1 ) compound, 1 -(4-chlorobenzyl)-1 H- im idazole-4,5-dicarboxam ide.

Various embodiments of the new DAMN process described herein, enable greater ease of production, milder reaction conditions, reduced reaction time cycles, fewer reaction intermediates and isolations, higher yields, re-use of solvents, higher purity and lower cost of goods compared to earlier published processes.

In one aspect, is a process for preparing 1 -(4-chlorobenzyl)-1 H-imidazole-4,5- dicarbonitrile by reacting a solution of diaminomaleonitrile, diglyme and formic acid at about 45°C for 45 minutes, then heat to reflux at about 150°C for about 3.5 hours, then cool to about 60°C. Re-heat the mixture under vacuum to about 80°C to remove distillate and then add anhydrous potassium carbonate. Once effervescence ceases, add 4-chlorobenzyl chloride, and optionally, a tetraalkylammonium salt, to the mixture while stirring for about 24 hours at about 75°C; or once effervescence ceases, adding 4- chlorobenzyl chloride and a tetraalkylammonium salt, to the mixture while stirring for about 24 hours at about 75°C. The preferred tetraalkylammonium salt is methyltributylammonium chloride (MTBAC). Then allowing the mixture to cool to about 60°C, placing under a vacuum and re-heating to about 80°C while removing distillate and then cooling again to about 25°C. Adding activated carbon to the mixture and filter, add water dropwise to the filtrate over about 15 minutes while stirring vigorously for an hour. Filter the mixture and rinse the resultant solids with water and dry the solids in vacuo over about 24 hours at about 60°C.

In another aspect, is a process for preparing 1 -(4-chlorobenzyl)-1 H-imidazole- 4,5-dicarbonitrile by reacting a solution of diaminomaleonitrile, diethyl carbonate and formic acid at about 45°C for about 45 minutes, then refluxing at about 120°C for about 4 hours, then cooling to about 25°C. Reheat under vacuum to about 40°C to remove distillate and then add anhydrous potassium bicarbonate to the mixture. Once effervescence ceases, add dimethylacetamide, 4-chlorobenzyl chloride, and optionally, a tetraalkylammonium salt, while stirring for about 24 hours at about 95°C; or once effervescence ceases, add dimethylacetamide, 4-chlorobenzyl chloride, and a tetraalkylammonium salt, while stirring for about 24 hours at about 95°C.

A preferred tetraalkylammonium salt is MTBAC. Allow the mixture to cool to about 25°C and filter. Add water to the filtrate dropwise while stirring over about 15 minutes as a solid forms, add heptane while stirring for about 30 minutes. Filter the mixture and wash the solids with water and dry the solids in vacuo over about 24 hours at about 50°C. In another aspect, is a process for preparing 1 -(4-chlorobenzyl)-1 H-imidazole- 4,5-dicarbonitrile by reacting a solution of diaminomaleonitrile, dipropylene glycol dimethyl ether (DPGDME) and formic acid with heat to about 130°-150°C for about 3.5 hours, then cooling. Re-heating the mixture under vacuum to remove distillate then adding a carbonate salt, 4-chlorobenzyl chloride, and optionally, a quaternary ammonium salt with additional heating for about 24 hours; or re-heating the mixture under vacuum to remove distillate then adding a carbonate salt, 4-chlorobenzyl chloride, and a tetraalkylammonium salt with additional heating for about 24 hours. Then cooling and reheating under vacuum to remove more distillate. Cool and add water dropwise while stirring vigorously. Filter the reactants and rinse the resultant black solids with water and heptane and dry the solids in vacuo. Dissolve the solids in hot isopropanol and add activated carbon, filter through Celite® or cellulose powder and concentrate the filtrate in vacuo to afford the product as an orange solid. The afforded product can be recrystallized from isopropanokwater (7:3) or propanol :water (7:3).

In another aspect, is a process for preparing 1 -(4-chlorobenzyl)-1 H-imidazole- 4,5-dicarbonitrile by reacting a solution of diaminomaleonitrile, DPGDME and formic acid at about 45°C for about 45 minutes, followed by heating to about 145°C for about 3.5 hours, then cooling to about 60°C. Re-heating the mixture to about 80°C under vacuum to remove distillate then adding anhydrous potassium carbonate or potassium bicarbonate. Once effervescence ceases, add 4-chlorobenzyl chloride and optionally, a tetraalkylammonium salt, to the mixture and heat to about 95°C for about 24 hours; or once effervescence ceases, add 4-chlorobenzyl chloride and a tetraalkylammonium salt to the mixture and heat to about 95°C for about 24 hours. A preferred tetraalkylammonium salt is MTBAC. Cool to about 60°C and then re-heat under vacuum to about 80°C to remove more distillate. Allow mixture to cool to about 25°C then add water dropwise over about 15 minutes while stirring vigorously for about an hour. Filter the reactants and rinse the black solids with water and heptane or water and dry the solids in vacuo at over about 24 hours at about 60°C. Dissolve the solids in hot isopropanol and add activated carbon to the mixture then filter through Celite® or cellulose powder and concentrate the filtrate in vacuo to afford the product (orange solid). The afforded product can be recrystallized from isopropanokwater (7:3) or propanokwater (7:3).

In another aspect, is a process for preparing 1 -(4-chlorobenzyl)-1 H-imidazole- 4,5-dicarbonitrile by reacting a solution of diaminomaleonitrile, fresh DPGDME (or fresh and re-used DPGDME) and fresh formic acid (or fresh and re-used formic acid) in a reactor to remove water during the condensation reaction by heating the mixture to about 40-50°C for about an hour and then heating to 130-150°C for about 3-4 hours while discarding solvent-water azeotropic distillate. Cooling to about 50°C and heating to about 100°C under vacuum to collect solvent distillate. Cool to about 50°C and add potassium bicarbonate. Stir for about an hour then add 4-chlorobenzyl chloride and optionally, a tetraalkylammonium salt; or stir for about an hour then add 4-chlorobenzyl chloride and a tetraalkylammonium salt. The preferred tetraalkylammonium salt is MTBAC. Heat to about 100°C for about 1-2 hours while discarding water. Heat to about 110-120°C for about 8 hours, cool to about 50°C, and re-heat to about 100°C under vacuum to collect solvent distillate. Cool to about 50°C and add water over about 30 minutes with vigorous stirring. Filter the mixture and rinse the solids with water and heptane and dry the solids. Add the solids to acetone, activated carbon and Celite® or cellulose powder and stir the mixture for about 24 hours at ambient temperature. Filter the mixture through Celite® or cellulose powder and wash the solids with acetone. Concentrate the filtrate in vacuo and recrystallize from isopropanokwater (7:3) or propanokwater (7:3).

In another aspect, is a process for preparing 1 -(4-chlorobenzyl)-1 H-imidazole- 4,5-dicarbonitrile by reacting a solution of diaminomaleonitrile, fresh DPGDME (or fresh and re-used DPGDME) and fresh formic acid (or fresh and re-used formic acid) in a reactor to remove water during the condensation reaction by heating the mixture to about 45°C for about 45 minutes and then heating to 135-140°C for about 3.5 hours while discarding solvent-water azeotropic distillate. Cool to about 50°C and heat to about 100°C under vacuum to collect solvent distillate. Cool to about 50°C and add potassium bicarbonate over about 30 minutes. Stir for about 45 minutes at about 50°C or until effervescence ceases then add 4-chlorobenzyl chloride and optionally, a tetraalkylammonium salt; or stir for about 45 minutes at about 50°C or until effervescence ceases then add 4-chlorobenzyl chloride and a tetraalkylammonium salt. The preferred tetraalkylammonium salt is MTBAC. Heat to about 100°C for about 1 .5 hours while discarding solvent-water azeotropic distillate. Heat to about 115°C for about 8 hours, cool to about 50°C, and re-heat to about 100°C under vacuum to collect solvent distillate. Cool to about 50°C and add water over about 30 minutes with vigorous stirring. Filter the mixture and rinse the solids with water and heptane and dry the solids. Add the solids to acetone, activated carbon and Celite® or cellulose powder and stir the mixture for about 24 hours at ambient temperature. Filter the mixture through Celite® or cellulose powder and wash the solids with acetone. Concentrate the filtrate in vacuo and recrystallize from isopropanokwater (7:3) or propanokwater (7:3). The collected solvent distillates were combined and re-used for subsequent reactions that occurred at least 4-months apart without issue. The combined solvent distillate (~1000mL and 700mL) was analyzed by ¹H NMR (600 MHz, DMSO-cfe) and Karl Fischer titration and found to contain 92.8% DPGDME, 6.62% formic acid and 0.56% water (~w/w%).

In another aspect, is a process for preparing 1 -(4-chlorobenzyl)-1 H-imidazole- 4,5-dicarbonitrile by reacting a solution of diaminomaleonitrile, DPGDME and formic acid in a reactor with N2 sweep to remove water during the condensation reaction by heating the mixture to about 130-150°C for about 3 hours, followed by cooling the reactor. Placing the reactor under vacuum and reheating to reduce reactor solvent volume by half by collecting solvent and excess formic acid distillate. Cooling again with stirring. Adding potassium bicarbonate, heating under vacuum and discarding solvent-water azeotropic distillate followed by cooling. With no vacuum, adding 4-chlorobenzyl chloride and optionally, a tetraalkylammonium salt while heating with N2 sweep for about 22 hours while discarding solvent-water azeotropic distillate, followed by cooling to about 50°C; or with no vacuum, adding 4-chlorobenzyl chloride and a tetraalkylammonium salt while heating with N2 sweep for about 22 hours while discarding solvent-water azeotropic distillate, followed by cooling to about 50°C. The preferred tetraalkylammonium salt is MTBAC. Then placing the reactor under vacuum then reheating to about 100°C to reduce reactor solvent volume by two thirds by collecting excess solvent distillate. Cooling, adding water, filtering and rinsing the solids with heptane and water and drying. Dissolving the solids in acetone and adding activated carbon and stirring for about 24 hours at room temperature. Filtering and washing the solids with acetone, then concentrating the filtrate in vacuo to afford the Formula (1 ) product which can recrystallized from isopropanokwater or propanokwater. Alternatively, the crude solids can be dissolved in hot (>60°) isopropanokwater (7:3) then adding activated carbon while stirring hot for about 24 hours. Filtering the solids and washing with hot (>60°C) isopropanokwater (7:3), then cooling and filtering the crystallized product.

In another aspect, is a process for preparing 1 -(4-chlorobenzyl)-1 H-imidazole- 4,5-dicarbonitrile by reacting a solution of diaminomaleonitrile, fresh DPGDME (or fresh and re-used DPGDME) and fresh formic acid (or fresh and re-used formic acid) in a reactor with N2 sweep to remove water during the condensation reaction by heating the mixture to about 40°C for about 1 hour and then heating to about 130-150°C for about 3 hours. Cooling the reactor to about 50°C and re-heating to about 90°C under vacuum to reduce reactor solvent volume by about half by collecting solvent and excess formic acid distillate. Without vacuum, cool to about 30°C with overnight stirring. Heat to about 50°C and add potassium bicarbonate while stirring for about an hour. Heat to about 80°C under vacuum and discard solvent-water azeotropic distillate. Without vacuum, cool to about 50°C while adding 4-chlorobenzyl chloride and optionally, a tetraalkylammonium salt; or without vacuum, cool to about 50°C while adding 4-chlorobenzyl chloride and a tetraalkylammonium salt. The preferred tetraalkylammonium salt is MTBAC. Heat to about 105°C with a nitrogen sweep for about 22 hours and discard solvent-water azeotropic distillate. Cool to about 50°C then re-heat to about 100°C under vacuum to reduce reactor solvent volume by about two thirds by collecting excess solvent distillate. Cool to about 60°C, then adding water over about an hour, cooling further to about 25°C while stirring for about an hour. Filter the mixture and rinse the solids with heptane and water and dry the black solids. Dissolve the solids in acetone and add activated carbon and stir for about 24 hours at room temperature. Filter the mixture and wash the solids with acetone. Concentrate the filtrate in vacuo to afford the product (orange solid). The afforded product can be recrystallized from isopropanokwater (7:3) or propanokwater (7:3). Alternatively, the crude solids can be dissolved in hot (>60°C) isopropanokwater (7:3) then adding activated carbon while stirring hot (>60°C) for about 24 hours. Filtering the solids and washing with hot (>60°C) isopropanokwater (7:3), then cooling and filtering the crystallized product.

In another aspect, is a process for preparing 1 -(4-chlorobenzyl)-1 H-imidazole- 4,5-dicarbonitrile by reacting a solution of diaminomaleonitrile, fresh DPGDME (or fresh and re-used DPGDME) and fresh formic acid (or fresh and re-used formic acid) in a reactor with N2 sweep to remove water during the condensation reaction by heating the mixture to about 40°C for about 1 hour and then heating to 135-140°C for about 3 hours. Cooling the reactor to about 50°C and re-heating to about 90°C under vacuum to reduce reactor solvent volume by about half by collecting solvent and excess formic acid distillate. Without vacuum, cool to about 30°C with stirring. Heat to about 50°C and add potassium bicarbonate portion-wise over about 30 minutes. Continue stirring at about 50°C for about an hour or until effervescence ceases. Heat reactor to about 80°C under vacuum and discard solvent-water azeotropic distillate. Without vacuum, cool reactor to about 50°C then add 4-chlorobenzyl chloride, and optionally, MTBAC; or without vacuum, cool reactor to about 50°C then add 4-chlorobenzyl chloride and MTBAC. Heat to about 105°C with a 5L/m inute nitrogen sweep for about 22 hours and discard solvent-water azeotropic distillate. Cool to about 50°C then re-heat to about 100°C under vacuum to reduce reactor solvent by about two thirds by collecting excess solvent distillate. Cool to about 60°C then adding water portion-wise over about 40 minutes while cooling further to about 25°C and stirring for about an hour. Filter the mixture and rinse the solids with heptane and water and dry the black solids. Dissolve the solids in acetone and add activated carbon and stir for about 24 hours at room temperature. Filter the mixture and wash the solids with acetone. Concentrate the filtrate in vacuo to afford the product (orange solid). The afforded product can be recrystallized from isopropanokwater (7:3) or propanokwater (7:3).

Alternatively, in-lieu of dissolving the resultant solids in acetone (as described above), the solids can be dissolved in isopropanol and mixed with activated carbon while heating to about 70°C for about 24 hours. While still hot, the mixture is filtered and washed with hot isopropanol and the filtrate concentrated in vacuo to afford 1 -(4-chlorobenzyl)-1 H-imidazole-4,5-dicarbonitrile, as an orange solid which can be recrystallized from isopropanokwater (7:3) or propanokwater (7:3), as described herein.

In another aspect, is a process for preparing 1 -(4-chlorobenzyl)-1 H-imidazole- 4,5-dicarbonitrile by reacting a solution of diaminomaleonitrile, fresh DPGDME (or fresh and re-used DPGDME) and fresh formic acid (or fresh and re-used formic acid) in a reactor with N2 sweep to remove water during the condensation reaction by heating the mixture to about 40°C for about 1 hour and then heating to about 135-140°C for about 3 hours. Cooling the reactor to about 50°C and re-heating to about 90°C under vacuum to reduce reactor solvent volume by about half by collecting solvent and excess formic acid distillate. Without vacuum, cooling to about 30°C with overnight stirring then heating to about 50°C and adding potassium bicarbonate while stirring for about an hour. Heating to about 80°C under vacuum and discarding solvent-water azeotropic distillate. Without vacuum, cooling to about 50°C while adding 4-chlorobenzyl chloride and optionally, a tetraalkylammonium salt; or without vacuum, cooling to about 50°C while adding 4-chlorobenzyl chloride and a tetraalkylammonium salt. A preferred tetraalkylammonium salt is MTBAC. Heating to about 105°C with a nitrogen sweep for about 22 hours and discarding solvent-water azeotropic distillate. Cooling to about 50°C then re-heating to about 120°C under vacuum to reduce reactor solvent volume by about two thirds by collecting excess solvent distillate. Cooling to about 60°C while adding water, then cooling further to about 25°C while stirring for about an hour. Filtering the mixture and rinsing the solids with heptane and water and drying the solids. Dissolving the solids in acetone and adding activated carbon and stirring for about 24 hours at room temperature. Filtering the mixture and washing the solids with acetone. Concentrating the filtrate in vacuo to afford the product (orange solid). The afforded product can be recrystallized from isopropanokwater (7:3) or propanokwater (7:3). Alternatively, the crude solids can be dissolved in hot (>60°C) isopropanokwater (7:3, 1 :9 or 2:8) then adding activated carbon while stirring hot (>60°C) for about 24 hours. Filtering the solids and washing with hot (>60°C) isopropanokwater (7:3), then cooling and filtering the crystallized product. Charging the crystallized product to a reactor with propanokwater (7:3, 1 :9 or 2:8) and heating to about 70°C. Once solids are dissolved, adding KOH and heating reactor to reflux (about 87°C) for about 1 .5 hours; then adding more KOH and heating for about 22 hours. Cooling the mixture and filtering the solids then rinsing with propanokwater (1 :1 ) and drying the solids in vacuo.

In another aspect, is a process for preparing 1 -(4-chlorobenzyl)-1 H-imidazole- 4,5-dicarbonitrile by reacting a solution of diaminomaleonitrile, fresh DPGDME (or fresh and re-used DPGDME) and fresh formic acid (or fresh and re-used formic acid) in a reactor with N2 sweep to remove water during the condensation reaction by heating the mixture to about 40°C for about 1 hour and then heating to about 135-140°C for about 3 hours. Cooling the reactor to about 50°C and re-heating to about 90°C under vacuum to reduce reactor solvent volume by about half by collecting solvent and excess formic acid distillate. Without vacuum, cooling to about 30°C with overnight stirring. Heating to about 50°C and adding potassium bicarbonate while stirring for about an hour. Heating to about 80°C under vacuum and discarding solvent-water azeotropic distillate. Without vacuum, cooling to about 50°C while adding 4-chlorobenzyl chloride and optionally, MTBAC; or without vacuum, cooling to about 50°C while adding 4-chlorobenzyl chloride and MTBAC. Heating to about 105°C with a nitrogen sweep for about 22 hours and discarding solvent-water azeotropic distillate. Cooling to about 50°C then re-heating to about 120°C under vacuum to reduce reactor solvent volume by about two thirds by collecting excess solvent distillate. Cooling to about 60°C while adding water, cooling further to about 25°C while stirring for about an hour. Filtering the mixture and rinsing the solids with heptane and water and drying the solids. Dissolving the solids in acetone and adding activated carbon and stirring for about 24 hours at room temperature. Filtering the mixture and washing the solids with acetone. Concentrating the filtrate in vacuo to afford the product (orange solid). The afforded product can be recrystallized from isopropanokwater (7:3) or propanokwater (7:3). Alternatively, the afforded product can be recrystallized from isopropanokwater (1 :9) or propanokwater (1 :9). Alternatively, the afforded product can be recrystallized from isopropanokwater (2:8) or propanokwater (2:8). Alternatively, the crude solids can be dissolved in hot (>60°C) isopropanokwater (7:3) then adding activated carbon while stirring hot (>60°C) for about 24 hours. Filtering the solids and washing with hot (>60°C) isopropanokwater (7:3), then cooling and filtering the crystallized product. Charging the crystallized product to a reactor with isopropanokwater (2:8) heating to about 70°C. Adding KOH and then heating to about 90°C for about 10 hours under pressure at about 5-15psi. Cooling the mixture and filtering the solids, then rinsing the solids with isopropanokwater (1 :1 ) and drying the solids in vacuo.

Note: In the processes described herein, the solids (black) dissolve in acetone at about or near room temperature and in hot isopropanol.

In another aspect, is a process for preparing 1 -(4-chlorobenzyl)-1 H-imidazole-

4,5-dicarboxamide (Formula 1 ) by adding concentrated sulfuric acid to 1 -(4- chlorobenzyl)-1H-imidazole-4,5-dicarbonitrile and stirring for about 16 hours at about 20-45°C.

4,5-dicarboxamide (Formula 1 ) by stirring 1-(4-chlorobenzyl)-1 /-/-imidazole-4,5- dicarbonitrile in ethanol-water (7:3, 1 :9 or 2:8) and KOH or isopropanokwater (7:3, 1 :9 or 2:8) and KOH or NaOH, each for about 24 hours at reflux (about 78-80°C). Cooling the mixture and filtering and washing the solids with the respective alcohol-water (1 :1 ) solvent and drying the solids in vacuo.

4,5-dicarboxamide (Formula 1 ) by stirring 1-(4-chlorobenzyl)-1 /7-imidazole-4,5- dicarbonitrile in isopropanokwater (7:3, 1 :9 or 2:8) and KOH and heated in a pressure vessel to about 90°C for about 10 hours under pressure at about 5-15psi. Cooling the mixture and filtering and washing the solids with isopropanokwater (1 :1 ) and drying the solids in vacuo.

4,5-dicarboxamide (Formula 1 ) by stirring 1-(4-chlorobenzyl)-1 /7-imidazole-4,5- dicarbonitrile in propanokwater (7:3, 1 :9 or 2:8) and KOH and heated to reflux (about 87°C) for about 24 hours. Cooling the mixture, filtering and washing the solids with propanokwater (1 :1 ) and drying the solids in vacuo.

4,5-dicarboxamide (Formula 1 ) by stirring 1-(4-chlorobenzyl)-1 /7-imidazole-4,5- dicarbonitrile in n-butanokwater (7:3, 1 :9 or 2:8) and KOH and heated to reflux (about 90°C) for about 3 hours. Cooling the mixture, filtering and washing the solids with n- butanokwater (1 :1 ) and drying the solids in vacuo.

In another aspect, is a process for preparing 1-(4-chlorobenzyl)-1 H-imidazole- 4,5-dicarboxamide (Formula 1 ) by stirring 1-(4-chlorobenzyl)-1 /-/-imidazole-4,5- dicarbonitrile in isopropanokwater (1 :4) and KOH and heated in a pressure vessel to about 90°C under nitrogen pressure (1 Opsi) for about 30 minutes with subsequent additions of KOH over about 8.5 hours. Cooling the depressurized mixture and filtering and washing the solids with isopropanokwater (1 :1 ) and drying the solids in vacuo.

DETAILED DESCRIPTION

Description of Figures:

Figure 1 . PXRD of crystalline 1 -(4-chlorobenzyl)-1 H-imidazole-4,5-dicarboxamide prepared using the DAMN process.

Figure 2. PXRD of crystalline 1 -(4-chlorobenzyl)-1 H-imidazole-4,5-dicarboxamide prepared using the US’376 process.

Figure 3. PXRD Overlay of crystalline 1-(4-chlorobenzyl)-1 H-imidazole-4,5 dicarboxamide prepared using the US’376 process (upper scan), the DAMN process (lower scan) and hand-ground crystals from the DAMN process (middle scan).

Figure 4. FTIR overlay scan of crystalline 1-(4-chlorobenzyl)-1 H-imidazole-4,5 dicarboxamide prepared using the US’376 process and the DAMN process.

Figure 5. DSC overlay scan of crystalline 1-(4-chlorobenzyl)-1 H-imidazole-4,5- dicarboxamide prepared using the US’376 process and the DAMN process.

For purposes of the present invention, as described and claimed herein, the following terms and phrases are defined as follows:

“About” when used in connection with a measurable numerical variable, refers to the indicated value of the variable and to all values of the variable that are within the experimental error of the indicated value (e.g., within the 95% confidence interval for the mean) or within 10 percent of the indicated value, whichever is greater. In some jurisdictions, the use of the term “about” is construed as unclear or ambiguous. In these jurisdictions, the term “about” can be readily deleted.

“Animal(s)”, as used herein, unless otherwise indicated, refers to an individual animal that is a mammal or a bird. Specifically, mammal refers to a vertebrate animal that is non-human, which are members of the taxonomic class Mammalia. Examples of non-human mammals include companion animals (/.e., feline, canine and equine) and livestock (/.e., swine, bovine, ovine and caprine). Birds are a group of warm-blooded vertebrates constituting the class Aves and are characterized by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart and a strong yet lightweight skeleton. Preferred birds are poultry and is defined as domestic fowl including chickens, turkeys, ducks, geese, swan, quail, pheasant, peafowl, and guineafowl raised for the production of meat or eggs. The preferred fowl is chicken.

“Fresh”, as used herein, unless otherwise indicated, refers to new and not previously used DPGDME or formic acid; e.g., poured, decanted or obtained directly from the manufacturer’s original storage container.

“Hot”, as used herein, unless otherwise indicated, when referring to isopropanol, is a temperature > 60°C, and preferably, about 70°C.

“Used”, as used herein, unless otherwise indicated, refers to DPGDME and formic acid that has been collected as a solvent distillate from at least one prior reactor synthesis of 1-(4-chlorobenzyl)-1 H-imidazole-4,5-dicarbonitrile and stored for subsequent re-use with diaminomaleonitrile for the synthesis of 1-(4-chlorobenzyl)-1 H- imidazole-4,5-dicarbonitrile.

In addition, as used herein, unless otherwise indicated, “cellulose powder” is the Type 20 (20p) cellulose powder (Sigmacell cellulose) from Sigma-Aldrich®. Celite® is a registered mark for SiO2 diatomaceous earth from Millipore Sigma and has a particle size of about 0.02-0.1mm.

Intermediates/Compounds

• diaminomaleonitrile (DAMN, intermediate a). This intermediate is also referred to as 2,3-diaminomaleonitrileand (Z)-2,3-diaminomaleonitrile in the art. 1 H-im idazole-4,5-dicarbonitrile (intermediate b)

1 -(4-chlorobenzyl)-1 H-imidazole-4,5-dicarbonitrile (intermediate c)

1 -(4-chlorobenzyl)-1 H-imidazole-4,5-dicarboxamide (Formula 1 )

Phase-Transfer Catalysts

Phase transfer catalysts are used to enable the reaction in a heterogenous system between organic compounds soluble in organic solvents and compounds soluble in water, such as inorganic salts. The phase transfer catalyst is soluble in both solvents, and it carries anions of inorganic salts into organic solvents and returns them into the water phase. Reactions usually progress under mild conditions with easy workup procedures. For this reason, they are also used industrially. Typical phase-transfer catalysts include for example: polyethylene glycol (PEG), onium salts and crown ethers. The onium salts include the quaternary ammonium salts, particularly, tetraalkylammonium salts and phosphonium salts. Some non-exclusive examples of PEG and quaternary ammonium salts include, for example: PEG 400 and PEG 300; benzyltriethylammonium chloride, methyltricaprylammonium chloride, tetramethylammonium chloride, tetramethylammonium bromide, tetraethylammonium bromide, tetraethylammonium chloride, tetrabutylammonium chloride, methyltributylammonium chloride, tetrabutylammonium thiocyante, methyltrioctylammonium chloride, tetrabutylammonium bromide, methyltrioctylammonium bromide, respectively, and the like. The preferred quaternary ammonium salts are tetraalkylammonium salts, for example: tetramethylammonium chloride, tetraethylammonium chloride, methyltributylammonium chloride, methyltrioctylammonium chloride and tetrabutylammonium chloride. The crown ethers are cyclic chemical compounds that consist of a ring containing several ether groups. The most common crown ethers are cyclic oligomers of ethylene oxide, the repeating unit being ethyleneoxy, i.e., -CH2CH2O-. Important members of this series are the tetramer (n=4), the pentamer (n=5), and the hexamer (n=6). Crown ethers strongly bind certain cations, forming complexes. The oxygen atoms are well situated to coordinate with a cation located at the interior of the ring, whereas the exterior of the ring is hydrophobic. The resulting cations often form salts that are soluble in nonpolar solvents, and for this reason crown ethers are useful in phase transfer catalysis.

Examples

The following acronyms described herein include: ethanol (EtOH); isopropanol (IPA); methyl (Me); ethyl (Et); methanol (MeOH); hydrochloric acid (HCI); acetonitrile (MeCN, CH3CN, Acn); potassium hydroxide (KOH); sodium hydroxide (NaOH); butylated hydroxytoluene (BHT); butylated hydroxyanisole (BHA); diaminomaleonitrile (DAMN); dipropyleneglycol dimethyl ether (DPGDME); diethylene glycol dimethyl ether (diglyme, DEGDME); potassium bicarbonate (KHCO3); methyltributylammonium chloride (MTBAC); ammonium hydroxide (NH4OH); alcohol (ROH); sulfuric acid (H2SO4); magnesium oxide (MgO); aqueous (aq); equivalent (eq); volume (vol); minute (min); room temperature (RT) and pounds per square inch (psi).

The compound, 1-(4-chlorobenzyl)-1 H-imidazole-4,5-dicarbonitrile, can be prepared by reacting a solution of diaminomaleonitrile, with DPGDME (fresh, fresh and used or used) and formic acid (fresh, fresh and used or used) in a reactor. As described herein, used DPGDME and used formic acid is defined as DPGDME and formic acid that has been collected and saved as a solvent distillate from at least one prior reactor synthesis of 1 -(4-chlorobenzyl)-1 H-imidazole-4,5-dicarbonitrile. Fresh and used refers to a mixture of fresh and used DPGDME and/or formic acid that is to be reused in subsequent reactions for preparing 1-(4-chlorobenzyl)-1 H-imidazole-4,5- dicarbonitrile.

Scheme 1 describes the general procedure for the preparation of 1 -(4- chlorobenzyl)-1 H-imidazole-4,5-dicarboxamide (Formula 1 ) via 1-(4-chlorobenzyl)-1 H- imidazole-4,5-dicarbonitrile (intermediate c). It is to be understood, however, that the invention, as fully described herein, and as recited in the claims, is not intended to be limited by the details of the following scheme or modes of preparation. The starting materials and various reactants can be obtained from commercial sources, or are readily prepared from commercially available organic compounds, using well-known methods to one skilled in the art. SCHEME 1 . Preparation of the Formula (1 ) Compound

As described in Scheme 1 and by processes set forth herein, diaminomaleonitrile (DAMN, intermediate a) is charged to a reactor at room temperature. To this is added an alkyl carbonate (e.g., diethyl carbonate) or a glycol ether (e.g., diglyme (DEGDME) and DPGDME) and formic acid. The reactants are stirred, heated and cooled to prepare intermediate b (1 H-imidazole-4,5-dicarbonitrile). Deprotonation of 1 H- imidazole-4,5-dicarbonitrile with carbonate, bicarbonate or metal oxide and a tetraalkylammonium salt, for example, MTBAC, in the presence of 4-chlorobenzyl chloride or any benzyl halide is effective at around 50°C for about 30-60 minutes. Deprotonation using carbonates occurs at lower temperature in the same time frame. Once deprotonation is nearly complete, a portion of distillate is removed and then a base (e.g., KHCOs) and alkylating agent (e.g., 4-chlorobenzyl chloride) is added with MTBAC or other phase-transfer catalyst, for example a tetraalkylammonium salt. The solvent, DMA is also added in Step 2 if the alkyl carbonate was used in Step 1 . The reaction is placed under vacuum and heated and once the azeotrope distilled and the remaining distillate removed, the resulting solids, 1 -(4-chlorobenzyl)-1 H-imidazole-4,5- d icarbonitrile (c) are filtered off. The solids can be washed and recrystallized. In Step 3, 1-(4-chlorobenzyl)-1 H-imidazole-4,5-dicarbonitrile (intermediate c) is reacted with an aqueous alcohol (e.g., ethanol, isopropanol, propanol and n-butanol) and a base (e.g., KOH and NaOH) at atmospheric pressure or under pressure at varying temperatures over time to provide higher yields and higher purities of 1 -(4-chlorobenzyl)-1 H- imidazole-4,5-dicarboxamide (Formula 1 ). The current new process avoids the use of potentially harmful solvents and the need for exceptional volumes of material as further described below.

In Step 1 , an earlier citation (Ohtsuka, Y; Chemistry of diaminomaleonitrile - selective preparations of mono-formyl diaminomaleonitrile and imidazoles by reaction with formic acid; Journal of Organic Chemistry (JOC), Vol.41 , No.4, 1976, pp.713-714) described the difficulty in preparing dicyanoimidazole from DAMN using formic acid as the condensation agent. While other formyl condensing agents, such as ortho-formates and formamides and formamidines have been shown to be effective, from a cost perspective, formic acid is preferred.

The JOC article further stated that the formation of 4,5-dicyanoimidazole using formic acid critically depends on the conditions under which the reaction is performed. For instance, a temperature of about 125°C is needed to effect imidazole ring formation and 135-140°C is ideal. The JOC article illustrated that condensation of DAMN with formic acid in a variety of solvents was shown to give low yields of 4,5- dicyanoimidazole, accompanied by the formation of tarry materials. It was further shown that the use of nonpolar solvents, such as xylenes, led to the hydrolysis of one of the nitriles, whereas polar solvents, such as formamide, led to the hydrolysis of both nitriles. In the same article, 4,5-dicyanoimidazole can be prepared (reflux, 6 hours, 76% yield) from DAMN in formic using the solvent diglyme (bis-(2-methoxyethyl) ether), a dimethyl ether of diethylene glycol, in high dilution (~43 volumes). While a high dilution reaction is feasible, it is not desirable from an industrial standpoint due to lower payloads, additional waste and higher cost. Reduced solvent volume leads to hydrolysis of one of the nitriles. Furthermore, diglyme is a toxic solvent which has recently been listed by the European Chemicals Agency as a substance of very high concern as a reproductive toxin, particularly for humans. As such, diglyme’s use in preparing pharmaceuticals, including those for animals intended to be consumed by humans, has been limited due to the potential of industrial exposure to the solvent or residual solvent in the finished drug product. Therefore, the use of diglyme for this reaction is not preferred due to the need for large volumes and more importantly, its potential toxicity.

Alternatively, DAMN and formic acid can be converted to 4,5-dicyanoimidazole using the industrial solvent, dipropylene glycol dimethyl ether (DPGDME). Surprisingly, only about 18 volumes of DPGDME need be used to prepare 4,5-dicyanoimidazole from DAMN rather than the 43 volumes of diglyme, by removing the water generated during the reaction. Towards this end, by heating a mixture of DAMN with formic acid in 18 volumes of DPGDME solvent at about 135°C using a nitrogen sweep through the reactor to aid removal of water gave, after workup, an 85% yield of 4,5- dicyanoimidazole.

In Step 2, prior art taught that 4,5-dicyanoimidazole can be alkylated with 4- chlorobenzyl chloride using either sodium hydride or potassium carbonate as a base in a polar solvent, such as dimethylformamide (US Patent 4,185,992). From a cost basis, it would be desirable if the condensation reaction and the subsequent alkylation step could be done in a single reactor, using a single common solvent. Telescoping reactions can bring tremendous cost savings to a process by avoiding extra solvents and processing time due to workup and product isolation (See: N.G. Anderson, Practical Process Research & Development; Academic Press: New York, 2012, pp.80,290). If excess formic acid and about half of the DPGDME solvent are removed after the condensation reaction, 4,5-dicyanoimidazole can be directly treated with a base and alkylated with 4-chlorobenzyl chloride to give 1-(4-chlorobenzyl)-4,5-dicyanoimidazole (Intermediate c) in good yield, avoiding workup and solid isolation of 4,5- dicyanoimidazole (Intermediate b).

When the condensation reaction is telescoped directly into the alkylation step, small amounts of a by-product, 4-cyanoimidazole-5-carboxamide, can be carried into the reaction. Use of either potassium carbonate or sodium hydride during the alkylation reaction causes this by-product to be alkylated on the amide nitrogen to give an alkylated amide by-product that is very difficult to remove from the reaction. Surprisingly, potassium bicarbonate rather than potassium carbonate, is an effective base for the alkylation reaction, and it causes minimal to no amide alkylation of the by- product, which helps during the streamlining of the final product purification of 1 -(4- chlorobenzyl)-4,5-dicyanoimidazole (Formula 1 ).

The use of carbonate bases, such potassium bicarbonate, in the alkylation step generate water and carbon dioxide as by-products. Water can react with one or both of the nitriles of intermediate c, generating by-products. As such, removal of water before and during the alkylation step minimizes nitrile hydrolysis. Furthermore, water can react with the alkylating agent, 4-chlorobenzyl chloride, generating 4-chlorobenzyl alcohol and hydrogen chloride. This side reaction requires the addition of excess potassium bicarbonate and 4-chlorobenzyl chloride to ensure complete consumption of 4,5- dicyanoimidazole. From a cost standpoint, this is not ideal. Rather, by first treating 4,5- dicyanoimidazole (b) with potassium bicarbonate, followed by azeotropic removal of most of the water generated, minimizes hydrolysis of 4-chlorobenzyl chloride once it’s added to the reactor and nitrile hydrolysis of intermediate c. Furthermore, by choosing a reaction temperature just above the boiling point of water and by using a nitrogen sweep through the reactor, any additional water generated during the alkylation reaction step can be effectively removed. In this way, only about 1 .4 equivalents of potassium bicarbonate and about 1.1 equivalents of 4-chlorobenzyl chloride are required to completely convert 4,5-dicyanoimidazole into 1-(4-chlorobenzyl)-4,5-dicyanoimidazole.

Once the alkylation reaction is complete, 1 -(4-chlorobenzyl)-4,5- dicyanoimidazole was isolated by adding water, causing the product to precipitate. As the alkylation reaction was performed in nine volumes of DPGDME solvent, a large excess of water was required to completely precipitate the product. In addition, the product tended to oil out, which made filtration difficult. However, by reducing the volume of solvent from nine volumes to 3 volumes, only 18 volumes of water were required to completely precipitate the product. In addition, the product was less likely to oil out under these conditions. The precipitated product was washed with water and heptane. The heptane wash removes excess 4-chlorobenzyl chloride as it could lead to by-product formation during the Step 3 hydrolysis reaction.

While the volume of solvent utilized in the above telescoped process was significantly reduced from 43 volumes to 18 volumes; from a cost standpoint, this was still not ideal. Therefore, distilled DPGDME solvent, generated after the Step 1 condensation and after the Step 2 alkylation, can be re-used directly in the process without any additional purification. Furthermore, the excess formic acid (~2 equivalents) that co-distills with DPGDME solvent after the Step 1 condensation reaction can also be reused in subsequent reactions to convert DAMN into 1 -(4-chlorobenzyl)-4,5- dicyanoimidazole without any additional purification. Hence, the overall usage of DPGDME solvent per run can be reduced from 18 volumes to 3 volumes. Also, the overall usage of formic acid can be reduced from 4 equivalents per reaction to 2 equivalents.

The crude 1-(4-chlorobenzyl)-4,5-dicyanoimidazole contained about 5-10% of byproducts resulting from hydrolysis of one or both of the nitriles. In addition, the product contained color bodies that gave the product a dark color. The color bodies were removed by treating the crude product with activated carbon (powder or cartridge) in acetone at ambient temperature. Alternatively, the crude product could be treated with activated carbon in an alcohol-water solvent mixture at elevated temperature. The alcohol-water mixture was preferred as acetone required stripping the solvent to dryness prior to the Step 3 hydrolysis.

The nitrile hydrolysis by-products, together with any other trace impurities, were removed via recrystallization from an alcohol-water mixture. In this way, 1 -(4- chlorobenzyl)-4,5-dicyanoimidazole could be isolated with a purity of about 99%. With the above improvements to the process, the overall product yields from DAMN to purified 1 -(4-chlorobenzyl)-4,5-dicyanoimidazole improved from about 40% to about 80% with lesser volumes and/or equivalents of reagents and/or waste.

Step 3. It was found that use of concentrated H2SO4 does not hydrolyze both nitrile groups at room temperature but stops after mono-hydrolysis providing only about 15% yield of the Formula (1 ) compound. Increasing the temperature to about 80°C for a period of about 1 hour increased the yield an additional 35%. Reducing the temperature to about 45°C for a longer period of time (16 hours) produced about 70% of the Formula (1 ) compound, but purification was quite difficult. In lieu of a strong acid, heating an aqueous methanol solution of 1 -(4-chlorobenzyl)-1 H-imidazole-4,5- dicarbonitrile in the presence of excess base led mostly to dicarboxylic acid due to overhydrolysis. Alternatively, reacting an aqueous mixture of different alcohols (e.g., ethanol, isopropanol, propanol and n-butanol) at different temperatures and time periods using a catalytic amount of KOH or NaOH provided a myriad of product yields. As noted above, the aqueous methanol and KOH reaction over a temperature range of 65-78°C for a period of about 24 hours yielded <10% of Formula (1 ). Changing the solvent to either ethanol, isopropanol, propanol or n-butanol in the presence of NaOH or KOH at higher temperatures (78-93°C) over a period of reaction durations provided higher yields of the Formula (1 ) product (86-94%) with higher purities (99%). In addition, the Step 3 reaction can be conducted under pressure (1-5 bars) versus at atmospheric pressure. The pressure allows the reaction to run at higher temperatures for a shorter period which allows the reaction to go to completion with lower amounts of impurities, particularly in an alcoholic solvent that has a lower azeotropic boiling point (e.g. ethanol and isopropanol) than propanol or n-butanol.

Step 1 . Preparation of 1 H-imidazole-4,5-dicarbonitrile (intermediate b)

In Step 1 , 865 grams of diaminomaleonitrile was charged to a 30 L reactor at room temperature. To this was added, 15.5 L of dipropylene glycol dimethyl ether (DPGDME) and the mixture was stirred at 300rpm. Formic acid (1206 mL) was added and the mixture was stirred at 30° for 45 minutes. The reactor was heated to 140°C under nitrogen sweep at 2 L/minute so as to allow the DPGDME-water azeotrope to distill at about 125°C. The nitrogen was increased to 5L/minute and then to 10 L/minute for about 2 minutes and then the nitrogen flow was reduced back to 2 L/minute. After about 3-hours, the reactor was cooled to 50°C and a house vacuum (~ 45torr) was applied to the reactants. Jacket temperature of the reactor was slowly increased to 110°C and 8.5L of distillate was collected in a separate reactor. The reactor was then cooled to 35°C and the reactants were allowed to stir overnight. The reactor was then heated to 50°C and 1121g of KHCOs in 100g portions was added over about 20 minutes. The mixture was stirred at 50°C until the effervescence slowed. Then 22.2g of methyltributylammonium chloride (MTBAC) and 1020mL of 4-chlorobenzyl chloride was added. The reaction was placed under vacuum at 120 torr and the reactants heated to 115°C slowly. Once the azeotrope distilled, the vacuum was removed while heating at 115° for about 7 hours. The reactor was cooled to 35°C and stirred overnight. The reactants were then placed under vacuum (57mm Hg) and the reactor heated to 95°C. About 4.2L of liquid distillate was removed and the reactor cooled to 55°C without further vacuum and heat. Added 14.4L of water through the top neck of the reactor over 20 minutes. Stir rate was increased to 400rpm for about 30 minutes. Black solid was filtered off through the bottom drain into a Buchner funnel with side discharge.

Step 2: Preparation of 1-(4-chlorobenzyl)-1 H-imidazole-4,5-dicarbonitrile (intermediate c)

2A. Use of diglyme:

To a stirred solution of diaminomaleonitrile (15g, 139mMol) in diglyme (250mL) in a 1 L, 3-neck flask equipped with a thermocouple and reflux condenser was added formic acid (21 mL, 565 mMol). The solution was warmed to 45°C for 45 minutes, followed by heating to reflux (150°C). Heating was continued for 3.5 hours, followed by cooling to 60°C. The reflux condenser was replaced with a simple distillation apparatus. The system was placed under vacuum (35 torr), followed by heating to 80°C. A total of 145mL of liquid was distilled from the reactor. The vacuum was broken, and to this mixture was added anhydrous potassium carbonate (23.1 g, 167 mMol) in one portion. Once effervescence had subsided, 4-chlorobenzyl chloride (17.2mL, 135 mMol) and MTBAC (385mg, 1 .63 mMol) were added. The mixture was stirred at 75°C for 24 hours. The mixture was cooled to 60°C, placed under vacuum (35 torr) and reheated to 80°C with a simple distillation apparatus. After collecting 60m L of distillate, the vacuum was broken, and the mixture was cooled to 25°C. The mixture was treated with activated carbon (3g) and filtered to afford a red solution. Water (300mL) was added dropwise to the mixture over 15 minutes. Once the addition was complete, the mixture was stirred vigorously for 1 hour. The reaction mixture was filtered through a Buchner funnel, and the cake was rinsed with water (50m L). The product was dried in vacuo at 60°C for 24 hours to afford 30g (89%) of 1-(4-chlorobenzyl)-1 /7-imidazole-4,5-dicarbonitrile as red solid with a purity of 85%. ¹H NMR (600 MHz, DMSO-cf₆) d 8.5 (s, 1 H), 7.5 (d, 2H), 7.4 (d, 2H), 5.5 (s, 2H).

2B. Use of a diethyl carbonate-dimethylacetamide solvent

To a stirred solution of diaminomaleonitrile (11.5g, 106 mMol) in diethyl carbonate (200mL) in a 1 L, 3-neck flask equipped with a thermocouple and reflux condenser was added formic acid (15.4mL, 426 mMol). The solution was warmed to 45°C for 45 minutes, followed by heating to reflux (120°C). Heating was continued for 4 hours, followed by cooling to 25°C. The reflux condenser was replaced with a simple distillation apparatus. The system was placed under vacuum (35 torr), followed by heating to 40°C. A total of 100m L of distillate was collected. The vacuum was broken and to this mixture was added anhydrous potassium bicarbonate (13.3g, 138 mMol) in one portion. Once effervescence had subsided, dimethylacetamide (DMA, 15mL), 4- chlorobenzyl chloride (13.1 mL, 108 mMol) and MTBAC (300mg, 1 .3 mMol) were added. The mixture was stirred at 95°C for 24 hours. The mixture was cooled to 25°C and filtered to remove tarry material. To the filtrate was added water (200mL) dropwise with stirring over 15 minutes, which caused a solid to form. Once the addition was complete, heptane (200mL) was added, and the whole mixture was stirred for 30 minutes. The mixture was filtered, and the solid was washed with water (50mL). The product was dried in vacuo at 50°C for 24 hours to afford 17.7g (69%) of 1 -(4-chlorobenzyl)-1 H- imidazole-4,5-dicarbonitrile as red solid with a purity of 80%.

2C. Use of DPGDME solvent

To a stirred solution of diaminomaleonitrile (10.8g, 100 mMol) in 200mL of DPGDME in a 1 L, 3-neck flask equipped with a thermocouple and reflux condenser was added formic acid (15mL, 400 mMol). The solution was warmed to 45°C for 45 minutes, followed by heating to 145°C. Heating was continued for 3.5 hours, followed by cooling to 60°C. The reflux condenser was replaced with a simple distillation apparatus. The system was placed under vacuum (35 torr), followed by heating to 80°C. A total of 100mL of liquid was distilled from the reactor. The vacuum was broken, and to this mixture was added anhydrous potassium carbonate (17.9g, 130 mMol) in one portion. Once effervescence had subsided, 4-chlorobenzyl chloride (12.8mL, 100 mMol) and MTBAC (390mg, 1 .7 mMol) were added. The mixture was stirred at 95°C for 24 hours. The mixture was cooled to 60°C, placed under vacuum (35 torr) and reheated to 80°C with a simple distillation apparatus. After collecting 50m L of distillate, the vacuum was broken, and the mixture was cooled to 25°C. Water (150mL) was added dropwise to the mixture over 15 minutes. Once the addition was complete, the mixture was stirred vigorously for 1 hour. The reaction mixture was filtered through a Buchner funnel, and the cake was rinsed with water (50mL) and heptane (150mL). The product was dried in vacuo at 60°C for 24 hours to afford the crude product (40 g) as a black solid. The above solid was dissolved in isopropanol (1 L) and treated with activated carbon (C-941 , Graver Technologies, 2g), filtered through Celite® or cellulose powder and concentrated in vacuo to afford 18g (70%) of 1 -(4-chlorobenzyl)-1/-/-imidazole-4,5-dicarbonitrile as an orange solid with a purity of 90%.

2D: Use of DPGDME solvent using potassium bicarbonate as a base without water removal during condensation reaction

To a stirred solution of diaminomaleonitrile (25.0g, 231 mMol) in 450mL of DPGDME in a 1 L, 3-neck flask equipped with a thermocouple and reflux condenser was added formic acid (33mL, 878 mMol). The solution was warmed to 45°C for 45 minutes, followed by heating to 145°C. Heating was continued for 3.5 hours, followed by cooling to 60°C. HPLC (240 nm) indicated a purity of 85% for the condensation product. The reflux condenser was replaced with a simple distillation apparatus. The system was placed under vacuum (35 torr), followed by heating to 80°C. A total of 200mL of liquid was distilled from the reactor. The vacuum was broken, and to this mixture was added anhydrous potassium bicarbonate (32.3g, 323 mMol) in one portion. Once effervescence had subsided, 4-chlorobenzyl chloride (30mL, 135 mMol) and MTBAC (700mg, 3.0 mMol) were added. The mixture was stirred at 95°C for 24 hours. The mixture was cooled to 60°C, placed under vacuum (35 torr) and reheated to 80°C with a simple distillation apparatus. After collecting 100mL of distillate, the vacuum was broken, and the mixture was cooled to 25°C. Water (600mL) was added dropwise to the mixture over 15 minutes. Once the addition was complete, the mixture was stirred vigorously for 1 hour. The reaction mixture was filtered through a Buchner funnel, and the cake was rinsed with water (250m L). The product was dried in vacuo at 60°C for 24 hours to afford the crude product (76 g). The solid was dissolved in isopropanol (2.5L) and treated with activated carbon (C-941 , Graver Technologies, 4g), filtered through Celite® or cellulose powder and concentrated in vacuo to afford 51 g (69%) of 1 -(4- chlorobenzyl)-1/-/-imidazole-4,5-dicarbonitrile as an orange solid with a purity of 91 %.

2E. Use of DPGDME solvent with water removal during condensation reaction and recrystallization of product

To a stirred solution of diaminomaleonitrile (108.1 g, 1.0 mol) in dipropylene glycol dimethyl ether (DPGDME, 1900mL) in a 3L, 3-neck flask equipped with a thermocouple and Dean-Stark apparatus was added formic acid (151 mL, 4.0 mol). The solution was warmed to 45°C for 45 minutes, followed by heating to 135°C. Heating was continued for 3.5 hours. A total of 40mL of distillate was collected in the Dean-Stark trap and sent to waste. HPLC (240 nm) indicated a purity of 92% for the condensation product. The mixture was cooled to 50°C. The Dean-Stark trap was replaced with a simple distillation apparatus. The system was placed under vacuum (35 torr), followed by heating to 100°C. A total of 1 L of distillate (mixture of DPGDME and formic acid) was collected and set aside for use in a subsequent experiment. The vacuum was broken, and the mixture was cooled to 50°C. To this mixture was added solid potassium bicarbonate (140g, 1 .4 mol) in 50g portions over 30 minutes. Once the addition was complete, the mixture was stirred at 50°C for 45 minutes or until effervescence subsided. To this mixture was added 4-chlorobenzyl chloride (153mL, 1.2 mol) and MTBAC (2.8g, 12 mMol). After complete addition, the distillation apparatus was replaced with a Dean- Stark apparatus. The mixture was placed under vacuum (35 torr) and heated to 100°C for 1 .5 hours. A total of 75mL of distillate was collected and sent to waste. The vacuum was broken, and the mixture was heated to 115°C for 8 hours or until the intermediate 4,5-dicyanoimidazole had been consumed. The mixture was cooled to 50°C, and the Dean-Stark apparatus was replaced with a simple distillation apparatus. The mixture was placed under vacuum (35 torr) and heated to 100°C. A total of 700mL of distillate (DPGDME) was collected and combined with the 1 L of distillate from above. The vacuum was broken, and the mixture was cooled to 50°C. Water (1800mL) was added to the reactor over 30 minutes with vigorous stirring. The reaction mixture was filtered through a Buchner funnel, and the cake was rinsed with water (400mL) and heptane (300mL) and suction dried to afford 317g of a black solid. The distillates from above (WOOmL + 700mL) were combined and analyzed by ¹H NMR (600 MHz, DMSO-de) and Karl Fischer titration and found to contain 92.8% DPGDME, 6.62% formic acid and 0.56% water (w/w). To a solution of the black solid (317g) in acetone (1 L) was added activated carbon (C-941 , Graver Technologies, 20g) and Celite® (8.5g) or cellulose powder. The mixture was stirred at ambient temperature for 24 hours. The mixture was filtered through Celite® or cellulose powder and washed with acetone (200mL). Concentration of the filtrate in vacuo afforded 275g of an orange solid. The above solid (275g) was recrystallized from isopropanokwater (580mL, 7:3) to afford 160g (66%) of 1 -(4-chlorobenzyl)-1H-imidazole-4,5-dicarbonitrile as tan solid with a purity of 99%.

2F. Re-use of DPGDME and formic acid

To a stirred solution of diaminomaleonitrile (108.1 g, 1.0 mol) in DPGDME (WOOmL consisting of WOOmL of re-used DPGDME from Example 2 and 400mL of fresh DPGDME) in a 3L, 3-neck flask equipped with a thermocouple and Dean-Stark apparatus was added formic acid (151 mL consisting of 87mL of re-used formic acid + 64mL of fresh formic acid, 4.0 mol). The solution was warmed to 45°C for 45 minutes, followed by heating to 135°C. Heating was continued for 3.5 hours. A total of 40mL of distillate was collected in the Dean-Stark trap and sent to waste. The mixture was cooled to 50°C. The Dean-Stark trap was replaced with a simple distillation apparatus. The system was placed under vacuum (35 torr), followed by heating to 100°C. A total of 1 L of distillate (mixture of DPGDME and formic acid) was collected. The vacuum was broken, and the mixture was cooled to 50°C. To this mixture was added solid potassium bicarbonate (140g, 1.4 mol) in 50g portions over 30 minutes. Once the addition was complete, the mixture was stirred at 50°C for 45 minutes or until effervescence subsided. To this mixture was added 4-chlorobenzyl chloride (153mL, 1.2 mol) and MTBAC (2.8g, 12 mMol). After complete addition, the distillation apparatus was replaced with a Dean-Stark apparatus. The mixture was placed under vacuum (35 torr) and heated to 100°C for 1 .5 hours. A total of 75mL of distillate was collected and sent to waste. The vacuum was broken, and the mixture was heated to 105°C for 12 hours or until the intermediate 4,5-dicyanoimidazole had been consumed. The mixture was cooled to 50°C, and the Dean-Stark apparatus was replaced with a simple distillation apparatus. The mixture was placed under vacuum (35 torr) and heated to 100°C. A total of 700mL of distillate (DPGDME) was collected. The vacuum was broken, and the mixture was cooled to 50°C. Water (1800mL) was added to the reactor over 30 minutes with vigorous stirring. The reaction mixture was filtered through a Buchner funnel, and the cake was rinsed with water (400mL) and heptane (300mL) and suction dried to afford 275g of a black solid. To a solution of the black solid (275g) in acetone (1 L) was added activated carbon (C-941 , Graver Technologies, 20g) and Celite® (8.5g) or cellulose powder. The mixture was stirred at ambient temperature for 24 hours. The mixture was filtered through Celite® or cellulose powder and washed with acetone (200mL). Concentration of the filtrate in vacuo afforded 235g of an orange solid. The orange solid was recrystallized from isopropanokwater (580mL, 7:3) to afford 154g (64%) of 1 -(4-chlorobenzyl)-1H-imidazole-4,5-dicarbonitrile as a tan solid with a purity of 99%.

2G. Re-use of DPGDME and Formic Acid Diaminomaleonitrile (865 g, 8.0 mol, 98%) and DPGDME (15.5 L consisting of 12.5 mL of re-used DPGDME and 3.5 L of fresh DPGDME) were charged to a 30 L reactor equipped with a thermocouple, stirring shaft, distillation apparatus and nitrogen sweep. Formic acid, (1471 g, 32 mol) consisting of 652 g of fresh feed and 819 grams of reused from a prior run, was added to the reactor. The reactor was heated to 40°C for 1 hour. The reactor was heated to 135°C for 3 hours or until starting material had been consumed. During this period, 250 mL of distillate was collected, and the nitrogen sweep aided this effort. The distillate was discarded. The reactor was cooled to 50°C and placed under house vacuum (45 torr). The jacket temperature was set to 90°C. As the reactor temperature reached 65°C, distillate began to collect in the receiver. After 100 mL had been collected, jacket temperature was increased to 110°C. After collecting a total of 525 mL of distillate (mixture of water, formic acid and solvent that was sent to waste), condenser temperature begins to rise rapidly to 80°C and distillate begins collecting at a steady rate. A total of 8.5 L of distillate (mixture of formic acid and solvent) was collected and saved for a future run. The vacuum was broken, and the reactor was cooled to 30°C and stirred overnight. The reactor was heated to 50°C. Solid potassium bicarbonate (1121 g, 11 .2 mol) was added in four portions over 30 minutes. Once the addition was complete, stirring was maintained at 50°C for 1 hour or until effervescence subsided. The reactor was placed under house vacuum (45 torr) and jacket temperature was set to 80°C. After 150 mL of distillate had been collected (mixture of water and solvent), the vacuum was broken, and reactor was cooled to 50°C. 4-Chlorobenzyl chloride (1391 g, 8.6 mol) and MTBAC (22.2 g, 0.096 mol) were charged to the reactor. The reactor was heated to 105°C with a 5 L/min nitrogen sweep for 22 hours. At this point, a total of 500 mL of distillate had collected in the trap (mixture of water and solvent); this was sent to waste. The reactor was cooled to 50°C and placed under house vacuum (45 torr). The jacket was set to 118°C, and reactor heating commenced. A total of 4 L of distillate was collected (condenser temperature 83°C) and combined with the 8.5 L of distillate collected from above. The reactor was cooled to 60°C and jacket heat was turned off. Water (14.4 L) was charged to the reactor over 40 minutes. After complete addition, reactor temperature was 38°C. The reactor was cooled to 25°C and stirred for 1 hour with increased agitator speed (600 rpm). The reaction mixture was filtered through a Buchner funnel, and the cake was rinsed with heptane (2.4 L), followed by water (3.0 L) and suction dried to afford 2.5 kg of wet cake as a black solid. The wet black solid (2.5 kg) was dissolved in acetone (9.6 L) in a 20 L carboy equipped with overhead stirrer. Activated carbon (C-941 , Graver Technologies, 160 g) was charged to the reactor, and the mixture was stirred at room temperature for 24 hours. The mixture was filtered through a sintered glass funnel dressed with 280 g of Cellulose (Sigma Cellulose, 50 microns). The filter cake was washed with 1 .5 L of acetone. The filtrate was concentrated in vacuo to afford 2.2 kg of an orange solid as a wet cake. The orange solid (2.2 kg) was recrystallized from propanokwater (4.3 L, 7:3) to afford 1.8 kg 1 -(4-chlorobenzyl)-1/-/-imidazole-4,5- dicarbonitrile, a light orange solid wet cake (1 .5 kg dry weight). Yield from diaminomaleonitrile was 79% with a purity of 99% based on ¹H NMR (DMSO-c/e).

2H. Re-use of DPGDME and Formic Acid

The preparation of 1-(4-chlorobenzyl)-1 /-/-imidazole-4,5-dicarbonitrile from diaminomaleonitrile was carried out in an identical fashion to that described in “2G” above; except the recrystallization of 1-(4-chlorobenzyl)-1 H-imidazole-4,5-dicarbonitrile was performed in isopropanol instead of propanol, affording 1500 grams (79%) of the title compound with a purity of 99% based on 1 H NMR (DMSO-de).

2I. Alternate Decolorization of Step 2 Product

The preparation of 1-(4-chlorobenzyl)-1 H-imidazole-4,5-dicarbonitrile was carried out in an identical fashion to that described in “2G” above; except a suspension of the black solid (242 g) in isopropanol (1350 mL, 5.6 vol) was added activated carbon (25 g, C-941 , Graver Technologies). The mixture was heated to 70°C for 24 hours. While still hot, the mixture was filtered through a 600 mL jacketed filter funnel (jacket temperature set to 65°C) containing a Celite® or cellulose powder bed. The filter cake was washed with hot (65°C) isopropanol (350 mL). The filtrate was concentrated in vacuo to afford 242 g of an orange solid. The above solid (242 g) was recrystallized from isopropanolwater (70:30, 425 mL) to afford 180 g (74%) of 1-(4-chlorobenzyl)-1 H-imidazole-4,5- dicarbonitrile as a yellow solid with a purity of 99%.

2J. Alternate Decolorization and Crystallization of Step 2 Product

The preparation of 1-(4-chlorobenzyl)-1 H-imidazole-4,5-dicarbonitrile was carried out in an identical fashion to that described in “2G” above; except a solution of the dried black solid (100 g) in hot (70°C) isopropanol (600 mL, 6 vol) in a jacketed round bottom flask (jacket set to 85°C) was fed through a 10 cm x 5 cm carbon cartridge apparatus (C-941 , Graver Technologies) using a peristaltic pump at a flow rate of 80 mL/minute. The permeate was collected and then passed through the cartridge again until the permeate was orange/yellow in color. Once the color changed, about 200 mL of additional hot IPA was fed through the cartridge to wash the system. The resulting permeate(s) were concentrated in vacuo at 60°C (84 torr) until a total volume of about 100 mL was reached. The vacuum was broken and IPA (40 mL) and water (60 mL) was added to make up a 7:3 IPA-water mixture. The whole mixture was heated to 75°C until a solution was obtained. The solution was cooled to 10°C over 3 hours, then stirred at 10°C for 30 minutes. The crystals were filtered and washed with 100 mL of cold IPA-water (70:30). The wet solid was dried in vacuo at 60°C overnight to afford 74 g (74%) of 1-(4-chlorobenzyl)-1 H-imidazole-4,5-dicarbonitrile as a yellow solid with a purity of 99%.

Step 3: Preparation of 1-(4-chlorobenzyl)-1 H-imidazole-4,5-dicarboxamide (Formula 1 )

3A. Use of concentrated sulfuric acid at room temperature 1 -(4-chlorobenzyl)-1/-/-imidazole-4,5-dicarbonitrile (500mg, 2.1 mMol) was added to concentrated sulfuric acid (5g) in a scintillation vial and stirred at 20°C for 16 hours. HPLC (240 nM) indicated 15% of 1 -(4-chlorobenzyl)-1 H-imidazole-4,5-dicarboxamide 80% of 1-(4-chlorobenzyl)-5-cyano-1/-/-imidazole-4-carboxamide and 5% starting material.

3B. Use of concentrated sulfuric acid at 80°C 1 -(4-chlorobenzyl)-1H-imidazole-4,5-dicarbonitrile (1000mg, 4.1 mMol) was added to concentrated sulfuric acid (5g) in a scintillation vial and stirred at 80°C for 1 hour. HPLC (240 nM) indicated 50% of 1 -(4-chlorobenzyl)-1 H-imidazole-4,5- dicarboxamide, 10% of 1 -(4-chlorobenzyl)-5-cyano-1 H-imidazole-4-carboxamide and 25% 1 H-imidazole-4,5-dicarboxamide.

3C. Use of concentrated sulfuric acid at 45°C:

1 -(4-chlorobenzyl)-1/-/-imidazole-4,5-dicarbonitrile (1000mg, 4.1 mMol) was added to concentrated sulfuric acid (5g) in a scintillation vial and stirred at 45°C for 16 hours. HPLC (240 nM) indicated 70% of 1 -(4-chlorobenzyl)-1 H-imidazole-4,5- dicarboxamide, 20% of 1 -(4-chlorobenzyl)-5-cyano-1 /-/-imidazole-4-carboxamide and 10% 1 H-imidazole-4,5-dicarboxamide.

3D. Use of potassium hydroxide in methanol-water

To a stirred solution of 1 -(4-chlorobenzyl)-1H-imidazole-4,5-dicarbonitrile (2.42g, 10 mMol) in methanol-water (11.5mL, 7:3) in a scintillation vial at 65°C was added potassium hydroxide (70pL of a 5.0 M aqueous solution, 3.5 mol%). The mixture was heated at 65°C for 6 hours before an additional 70mL (3.5 mol%) of 5M potassium hydroxide solution was added. The mixture was heated at 78°C for an additional 18 hours. HPLC indicated that <10% of 1-(4-chlorobenzyl)-1 /-/-imidazole-4,5- dicarboxamide had formed.

3E. Use of potassium hydroxide ethanol-water

To a stirred solution of 1 -(4-chlorobenzyl)-1H-imidazole-4,5-dicarbonitrile (2.42g, 10 mMol) in ethanol-water (11.5mL, 7:3) in a scintillation vial at 78°C was added potassium hydroxide (70pL of a 5.0 M aqueous solution, 3.5 mol%). The mixture was heated at 78°C for 6 hours before an additional 70mL (3.5 mol%) of 5M potassium hydroxide solution was added. The mixture was heated at 78°C for an additional 18 hours. The mixture was cooled to 25°C and filtered through a Buchner funnel. The cake was washed with 5m L of 1 :1 ethanol-water. The cake was dried in vacuo at 60°C for 24 hours to afford 2.40g (86%) of 1-(4-chlorobenzyl)-1 H-imidazole-4,5- dicarboxamide as an off-white solid with a purity of 99%.

3F. Use of isopropanokwater and potassium hydroxide To a stirred solution of 1 -(4-chlorobenzyl)-1/-/-imidazole-4,5-dicarbonitrile (124g, 0.51 mol) in isopropanokwater (585mL, 7:3) in a 3-neck flask equipped with thermocouple and reflux condenser at 80°C was added potassium hydroxide (1 .OmL of a 5.0 M aqueous solution, 1 .0 mol%). After 15 minutes, an additional 1 ,5mL (1 .5 mol%) of 5M potassium hydroxide was added. The mixture was heated at 80°C for 7 hours. An additional 3.5mL (3.5 mol%) of 5M potassium hydroxide was added, and the mixture was heated at 80°C for 17 hours. The mixture was cooled to 25°C and filtered through a Buchner funnel. The cake was washed with 250m L of 1 :1 isopropanokwater. The cake was dried in vacuo at 60°C for 24 hours to afford 127g (89%) 1-(4-chlorobenzyl)- 1 H-imidazole-4,5-dicarboxamide as an off-white solid with a purity of 99%.

3G. Use of isopropanokwater and sodium hydroxide

To a stirred solution of 1 -(4-chlorobenzyl)-1H-imidazole-4,5-dicarbonitrile (24.2g, 100 mMol) in isopropanokwater (118mL, 7:3) in a 3-neck flask equipped with thermocouple and reflux condenser at 80°C was added sodium hydroxide (500pL of a 5.0 M aqueous solution, 2.5 mol%). The mixture was heated at 80°C for 6 hours before an additional 500pL (2.5 mol%) of 5M sodium hydroxide solution was added. The mixture was heated at 80°C for 18 hours. The mixture was cooled to 25°C and filtered through a Buchner funnel. The cake was washed with 80m L of 1 :1 isopropanokwater. The cake was dried in vacuo at 60°C for 24 hours to afford 26.0g (94%) of 1 -(4- chlorobenzyl)-1 H-imidazole-4,5-dicarboxamide as an off-white solid with a purity of 99%.

3H. Use of isopropanokwater and potassium hydroxide under pressure

To a stirred suspension of 1 -(4-chlorobenzyl)-1 H-imidazole-4,5-dicarbonitrile (24.2 g, 100 mmol) in isopropanokwater (145 mL, 1 :4) in a 4-neck pressure flask equipped with thermocouple, reflux condenser, pressure gauge, rupture disk and pressure relief valve at 70°C was added potassium hydroxide (800 pL of a 5.0 M aq. solution, 4.0 mol%). The reactor was sealed and heated to 90°C (internal pressure ~5- 15 psi) for 1.5 hours before an additional 400 pL (2.0 mol%) of 5M potassium hydroxide solution was added. The mixture was heated at 90°C for 2 hours before an additional 400 pL (2.0 mol%) of 5M potassium hydroxide solution was added. The mixture was heated at 90°C for an additional 6 hours. The reactor was cooled to room temperature and filtered through a Buchner funnel. The cake was washed with 100 mL of 1 :1 isopropanokwater. The cake was dried in vacuo at 60°C for 24 hours to afford 26 g (93%) of 1-(4-chlorobenzyl)-1 H-imidazole-4,5-dicarboxamide as an off-white solid with a purity of 98%.

3I. Use of propanol: water

To a 30 L reactor was charged 1 -(4-chlorobenzyl)-1H-imidazole-4,5-dicarbonitrile (1.5 kg, 6.3 mol) and propanol : water (7.6 L, 7:3). The reactor was heated to 70°C. Once all solids dissolved, added potassium hydroxide (37.5 mL of a 5 M aqueous solution, 0.19 mol, 3 mol%). Reactor self-heated to 81 °C. Jacket temperature was set to 100°C, and the mixture was allowed to reflux for 1 .5 hours. Potassium hydroxide (25 mL of 5 M KOH, 0.13 mol, 2 mol%) was charged to the reactor, and heating was maintained for an additional 2 hours. Potassium hydroxide (25 mL of 5 M KOH, 0.13 mol, 2 mol%) was charged to the reactor, and heating was maintained for an additional 20 hours. The reactor was cooled to 50°C and the reactor was placed under vacuum (45 torr). After collecting 1 L of distillate, the vacuum was broken, and the reactor was cooled to 10°C. The mixture was filtered through a Buchner funnel. The cake was washed with 1 L of 1 :1 propanol: water. The cake was suction dried for 30 minutes, followed by further drying in vacuo at 60°C for 24 hours to afford 1 .5 kg (87%) of 1 -(4-chlorobenzyl)-1 H- imidazole-4,5-dicarboxamide as an off-white solid with a purity of 99%.

3J. Use of n-butanol: water

To a stirred solution of 1 -(4-chlorobenzyl)-1H-imidazole-4,5-dicarbonitrile (2.42g, 10 mMol) in n-butanol:water (11.5mL, 7:3) in a scintillation vial at 93°C was added potassium hydroxide (50pL of a 5.0 M aqueous solution, 2.5 mol%). The mixture was heated at 93°C for 1 .5 hours before an additional 50pL (2.5 mol%) of 5M potassium hydroxide solution was added. The mixture was heated at 93°C for an additional 1 .5 hours. The mixture was cooled to 25°C and filtered through a Buchner funnel. The cake was washed with 5m L of 1 :1 n-butanol:water. The cake was dried in vacuo at 60°C for 24 hours to afford 2.40g (86%) of 1 -(4-chlorobenzyl)-1 H-imidazole-4,5- dicarboxamide as an off-white solid with a purity of 99%.

3K. Modification of Preparation “3H” - Use of External Nitrogen Pressure and Higher Solvent Volume.

To a stirred suspension (900 rpm) of 1-(4-chlorobenzyl)-1 /7-imidazole-4,5- dicarbonitrile (121 g, 500 mmol) in isopropanokwater (1210 mL, 1 :4) in a 4-neck pressure flask equipped with thermocouple, reflux condenser, overhead stirrer and stir shaft possessing two agitator blades, pressure gauge, rupture disk, pressure relief valve and nitrogen inlet at 70°C was added potassium hydroxide (1 .0 mL of a 5.0 M aq. solution, 1 .0 mol%). The reactor was sealed and 10 psi of nitrogen pressure was applied. The reactor was heated to 90°C (internal pressure 15-20 psi) for 30 minutes before an additional 1.0 mL (1.0 mol%) of 5M potassium hydroxide solution was added. The mixture was heated at 90°C for 30 minutes before an additional 3.0 mL (3.0 mol%) of 5M potassium hydroxide solution was added. The mixture was heated at 90°C for an additional 2.5 hours before an additional 3.0 mL (3.0 mol%) of 5M potassium hydroxide solution was added. The mixture was heated at 90°C for an additional 5.5 hours. The reactor was cooled to room temperature, depressurized and filtered through a Buchner funnel. The cake was washed with isopropanokwater (150 mL, 1 :1 ). The cake was dried in vacuo at 60°C for 24 hours to afford 135 g (97%) of 1 -(4-chlorobenzyl)-1 H- imidazole-4,5-dicarboxamide as an off-white solid with a purity of 99%.

Overall solvent mixtures and applied pressure provided slightly different product yields, purities and particle sizes of 1-(4-chlorobenzyl)-1 H-imidazole-4,5-dicarboxamide from the hydrolysis reactions from 1 -(4-chlorobenzyl)-1/-/-imidazole-4,5-dicarbonitrile as shown in Table 1. The particle size distribution (PSD D90) describes the diameter wherein 90% of the distribution has a smaller particle size and 10% has a larger particle size. Table 1. Solvent Mixtures and Pressures for Preparing 1 -(4-chlorobenzyl)-1 H-imidazole- 4,5-dicarboxamide

Crystalline Form of 1 -(4-chlorobenzyl)-1 H-imidazole-4,5-dicarboxamide (Formula 1 )

A compound to be developed as a pharmaceutical agent needs to be reliably prepared and purified on a large scale and be stable. A crystalline, and preferably a high-melting form of the compound is therefore desirable since high-melting point crystalline solids tend to be easy to purify by crystallization and are more stable than an amorphous form. The crystalline form of 1 -(4-chlorobenzyl)-1 H-imidazole-4,5- dicarboxamide has not been previously characterized.

Different solid-state forms of a compound can have materially different physical properties. Such differences in physical properties can have an impact, for example, on how a pharmaceutical agent is made, processed, formulated or administered. For example, the crystalline form of a compound may have very different properties from an amorphous form, for example solubility, rate of dissolution, suspension stability, stability during grinding, vapor pressure, optical and mechanical properties, hygroscopicity, crystal size, filtration properties, desiccation, density, melting point, degradation stability, stability against phase transformation into other crystalline forms, color, and even chemical reactivity. Accordingly, the identification of the solid-state form (/.e., crystalline forms or polymorphs) of 1 -(4-chlorobenzyl)-1 H-imidazole-4,5-dicarboxamide that provide an advantage relative to other solid-state forms in making, processing, formulating or administering the compound are desirable. Characterization of Crystalline Forms

The crystalline powder X-ray diffraction (PXRD), Fournier-transform infrared (FT- IR) absorption spectroscopy and differential scanning calorimetry (DSC) patterns for the Formula (1 ) compound, 1-(4-chlorobenzyl)-1 H-imidazole-4,5-dicarboxamide, prepared by the DAMN process and the US’376 process are shown in the Figures.

Instrument and Method Powder X-Ray Diffraction (PXRD)

The X-ray d iff ractog rams were obtained using a Bruker D4 Endeavor equipped with a LynxEye detector operated with a fixed slit and a Cu source operated at 40 kV and 40 mA, K2a wavelength 1.5406 angstroms. The d iff ractog rams were obtained in locked coupled mode, from 5 to 45 degrees two-theta. The step size was 0.0257 degrees two-theta, and the acquisition time per step was 0.4 seconds. The divergent slit was set at 1 .00 degrees. A suitable blank diffractogram was subtracted. Zero background holders were employed in all tests, with the sample distributed across the surface in a thin flat layer. All tests were performed at controlled room temperature and humidity (typically 21 -22°C, 25-50%RH). During acquisition, the sample holder was rotated at 20 rpm. Data were analyzed in the EVA software package obtained from Bruker.

As will be appreciated by the skilled crystallographer, the relative intensities of the various peaks reported in Tables 2 and 3 and Figures 1 -3 herein may vary due to a number of factors such as orientation effects of crystals in the X-ray beam or the purity of the material being analyzed or the degree of crystallinity of the sample. The PXRD peak positions may also shift for variations in sample height but the peak positions will remain substantially as defined. The skilled crystallographer also will appreciate that measurements using a different wavelength will result in different shifts according to the Bragg equation - nA, = 2ci sinO. Such further PXRD patterns generated by use of alternative wavelengths are considered to be alternative representations of the PXRD patterns of the crystalline materials of the present invention and as such are within the scope of the present invention. Instrument and Method Fournier Transform Infrared Spectroscopy (FTIR)

The FTIR spectra were acquired using a Bruker FTIR Vertex 70 spectrometer equipped with a Pike Technologies MIRacle ATR single reflection ATR accessory (Ge Single Reflectance Plate). The spectra were collected at 4 cm-1 resolution with a coaddition of 64 scans. Because the FTIR spectra were recorded using single reflection ATR, no sample preparation was required. Using ATR FTIR will cause the relative intensities of infrared bands to differ from those seen in a 10 transmission FTIR spectrum using KBr disc or nujol mull sample preparations. Due to the nature of ATR FTIR, the bands at lower wavenumbers are more intense than those at higher wavenumbers.

Instrument and Differential Scanning Calorimetry

Differential scanning calorimetry was performed in a Mettler Toledo DSC 3+. Sample was placed in an aluminum 40 pL pan with a pierced lid. A suitable, empty reference pan of the same size and approximately the same weight was used. The sample was heated linearly from 25° to 240°C at 10°C/minute. The resulting melt endotherm was integrated in the STAR^e software package from Mettler Toledo.

Crystalline 1-(4-chlorobenzyl)-1 H-imidazole-4,5-dicarboxamide prepared according to US’376 and this new (DAMN) process exhibits a powder X-ray diffraction pattern substantially as shown in Figures 1 and 2, respectively. The characteristic peaks are expressed in degrees 20 [2-Theta⁰] (± 0.2°), interplanar spacings (d-spacing), and respective intensities (%) as displayed in Tables 2 and 3. One skilled in the art will recognize that intensities of the peaks in the diffractogram are a function of the orientation of the crystals in the sample, so physical modifications such as milling or hand grinding, or crystallization from a different solvent, may affect the intensity of the peaks, while their position remains unchanged, for the same crystal form. The DAMN process provides “platy” (/.e., flattened and thin) crystals that have different peak intensities because of the way they orient themselves on the flat sample holder. This is a common phenomenon known as preferred orientation. Hand grinding a sample gave different peak intensities, as seen in Table 3, proving the preferred orientation effect. As such the identity of the top five hand-ground sample peaks can change with the orientation of the crystals on the sampling plate, as depicted in Table 3. The PXRD scans for crystalline 1-(4-chlorobenzyl)-1 H-imidazole-4,5-dicarboxamide prepared using the US’376 process (upper scan), the DAMN process (lower scan) and the DAMN process hand-grounded (middle scan) sample are shown in Figure 3.

Table 2. PXRD of Crystalline 1 -(4-chlorobenzyl)-1 H-imidazole-4,5-dicarboxamide Prepared Using the US’376 process

Table 3. PXRD of Crystalline 1 -(4-chlorobenzyl)-1 H-imidazole-4,5-dicarboxamide

Prepared using the DAMN Process and Hand-Ground^A

Crystalline 1 -(4-chlorobenzyl)-1 H-imidazole-4,5-dicarboxamide exhibits a

Fournier-Transform Infrared (FT-IR) spectrum at the 1680 to 650cm'¹ range substantially as shown in Figure 4 with the following characteristic FT-IR peaks: 1679 cm-¹, 1659 cm-¹, 1592 erm¹, 1500 erm¹, 1411 erm¹, 1339 erm¹, 1273 cm’¹, 1132 erm¹, 1091 cm'¹, 1010 cm'¹, 810 cm'¹, 730 cm'¹, 680 cm'¹ and 651 cm'¹.

Crystalline 1 -(4-chlorobenzyl)-1 H-imidazole-4,5-dicarboxamide prepared using the IIS’376 process (upper scan) and the DAMN process (lower scan) also exhibits a differential scanning calorimetry (DSC) thermograms substantially as shown in Figure 5. The onset of the endotherm and predominant endotherm peaks for the crystalline 1-(4- chlorobenzyl)-1 H-imidazole-4,5-dicarboxamide prepared using the DAMN process was 216.98°C and 218.29°C, respectively. Respective onset and predominant peak endotherms for the crystalline 1 -(4-chlorobenzyl)-1 H-imidazole-4,5-dicarboxamide prepared using the US’376 process were 217.16°C and 218.30°C.

Claims

CLAIMS We Claim:

1 . A process for preparing a compound of Formula (1 )

comprising: a) reacting a solution of diaminomaleonitrile, DPGDME and formic acid in a reactor and heating the mixture to about 40°C for about 1 hour and then heating to about 135-140°C for about 3 hours; b) cooling the reactor to about 50°C and re-heating to about 90°C under vacuum to remove solvent distillate, removing the vacuum, and then cooling to about 30°C with stirring; c) heating to about 50°C and then adding potassium bicarbonate while stirring for about an hour then heating to about 80°C under vacuum and discarding solventwater azeotropic distillate, then without vacuum, cooling to about 50°C while adding 4-chlorobenzyl chloride and optionally, a quaternary ammonium salt; d) heating to about 105°C with a nitrogen sweep for about 22 hours and discarding the solvent-water azeotropic distillate then cooling to about 50°C then re-heating to about 100°C under vacuum to remove reactor solvent volume; e) cooling to about 60°C, then adding water over about an hour with further cooling to about 25°C while stirring and then filtering and rinsing the solids with heptane and water then drying the solids; f) dissolving the solids in acetone and adding activated carbon and stirring for about 24 hours at room temperature then filtering and washing the solids with acetone then concentrating the filtrate in vacuo to afford 1 -(4-chlorobenzyl)-1 H- imidazole-4,5-dicarbonitrile; or dissolving the solids in hot isopropanol and mixing with activated carbon and heating the mixture at about 70°C for about 24 hours, filtering the hot mixture and washing the solids with hot isopropanol, concentrating the filtrate under vacuum; and optionally, the 1 -(4-chlorobenzyl)- 1 H-imidazole-4,5-dicarbonitrile is recrystallized from an alcohol: water mixture; g) charging the 1 -(4-chlorobenzyl)-1 H-imidazole-4,5-dicarbonitrile to a reactor with an alcohokwater solution and heating to about 70°C; h) adding KOH and heating mixture to about 90°C under 0-20psi pressure for about 1 .5 hours and then adding more KOH with continued heating at about 90°C under 0-20psi pressure for about 22 hours; cooling the mixture, filtering and rinsing the solids with an alcohokwater solution and drying the solids to afford 1 - (4-chlorobenzyl)-1 H-imidazole-4,5-dicarboxamide.

2. The process of Claim 1 , step a, wherein the DPGDME is fresh and/or re-used from prior 1 -(4-chlorobenzyl)-1 H-imidazole-4,5-dicarbonitrile syntheses; and wherein the process in step c, further comprises a quaternary ammonium salt.

3. The process of Claim 1 or 2, step a, wherein the formic acid is fresh and/or rereused from prior 1 -(4-chlorobenzyl)-1 H-imidazole-4,5-dicarbonitrile syntheses; the tetraalkylammonium salt is MTBAC; the quaternary ammonium salt is a tetraalkylammonium salt; and wherein the mixture is heated with a nitrogen sweep to remove water from the reaction.

4. The process of Claim 3, step b, wherein about half of the solvent volume is removed from the reactor by distillation; the tetraalkylammonium salt in step c is methyltributylammonium chloride (MTBAC; and wherein about two thirds of the solvent from step d is removed from the reactor by distillation.

5. The process of Claim 4, wherein the solvents are combined and retained to be re-used for the synthesis of 1 -(4-chlorobenzyl)-1 H-imidazole-4,5-dicarbonitrile.

6. The process of Claim 5, step f, wherein the solids are dissolved in hot isopropanol and mixed with activated carbon while heating the mixture to about 70°C for about 24 hours, filtering the hot mixture and washing the solids with hot isopropanol and concentrating the filtrate under vacuum.

7. The process of Claim 6, step f, wherein the 1-(4-chlorobenzyl)-1 H-imidazole-4,5- dicarbonitrile is re-crystallized from an alcohokwater solution; and wherein the alcohol is selected from the group consisting of methanol, ethanol, propanol, isopropanol and n- butanol.

8. The process of Claim 7 wherein the alcohokwater ratio amount is 1 :1 , 1 :4, 1 :9, 3:7, 4:6, 6:4, 7:3 and 8:2; and wherein the 1 -(4-chlorobenzyl)-1 H-imidazole-4,5- dicarbonitrile is re-crystallized from isopropanokwater or propanokwater.

9. The process of Claim 8, wherein the isopropanokwater and propanokwater are each in the ratio amount of 7:3.

10. The process of Claim 1 , comprising: a) reacting a solution of diaminomaleonitrile, DPGDME and formic acid in a reactor with nitrogen sweep and heating the mixture to about 40°C for about 1 hour and then heating to about 135-140°C for about 3 hours to remove water; b) cooling the reactor to about 50°C and re-heating to about 90°C under vacuum to remove about half of the reactor solvent with distillation, removing the vacuum, and then cooling to about 30°C with overnight stirring; c) heating to about 50°C and then adding potassium bicarbonate portion-wise while stirring for about an hour then heating to about 80°C under vacuum and discarding solvent-water azeotropic distillate, then without vacuum, cooling to about 50°C while adding 4-chlorobenzyl chloride; or cooling to about 50°C while adding 4 chlorobenzyl chloride and MTBAC; d) heating to about 105°C with a nitrogen sweep for about 22 hours and discarding the solvent-water azeotropic distillate then cooling to about 50°C then re-heating to about 100°C under vacuum to remove about two thirds of the reactor solvent volume with distillation; e) cooling to about 60°C, then adding water portion-wise over about an hour and cooling further to about 25°C while stirring and then filtering and rinsing the solids with heptane and water then drying the solids; f) dissolving the solids in acetone and mixing with activated carbon and stirring for about 24 hours at room temperature then filtering and washing the solids with acetone then concentrating the filtrate in vacuo to afford 1 -(4-chlorobenzyl)-1 H- imidazole-4,5-dicarbonitrile, or dissolving the solids in hot isopropanol and mixing with activated carbon while heating at about 70°C for about 24 hours, filtering the hot mixture and washing the solids with hot isopropanol, concentrating the filtrate under vacuum; and optionally, re-crystallizing the 1 -(4-chlorobenzyl)-1 H- imidazole-4,5-dicarbonitrile from isopropanokwater (7:3) or propanol:water (7:3) and drying the crystal solids; g) charging the 1 -(4-chlorobenzyl)-1 H-imidazole-4,5-dicarbonitrile to a reactor with an isopropanokwater (20:80) solution then heating to about 70°C; h) adding KOH and heating mixture to reflux under 0-20psi pressure for about 1 .5 hours and then adding more KOH with continued heating under 0-20psi pressure for about 22 hours; cooling the mixture, filtering and rinsing the solids with an isopropanokwater (1 :1 ) solution and drying the solids to afford 1 -(4- chlorobenzyl)-1 H-imidazole-4,5-dicarboxamide.

11 . The process of Claim 1 or 10 wherein the solids from Step f are dissolved in hot isopropanol and mixed with activated carbon while stirring at about 70°C for about 24 hours then filtering the solids and washing with hot isopropanol, cooling and condensing the filtrate to afford the 1 -(4-chlorobenzyl)-1 H-imidazole-4,5-dicarbonitrile.

12. A process for preparing 1-(4-chlorobenzyl)-1 H-imidazole-4,5-dicarbonitrile comprising: a) reacting a solution of diaminomaleonitrile, diethyl carbonate and formic acid in a reactor at about 45°C for about 45 minutes, then refluxing at about 120°C for about 4 hours, then cooling to about 25°C; b) heating under vacuum to about 40°C to remove distillate, then adding anhydrous potassium bicarbonate while mixing; c) adding dimethylacetamide, 4-chlorobenzyl chloride, and optionally, MTBAC, while stirring for about 24 hours at about 95°C; d) cooling to about 25°C, filtering and then adding water to the filtrate while stirring for about 15 minutes as solids form, adding heptane with additional stirring; e) filtering and washing the solids with water then drying the solids in vacuo; f) dissolving the solids in acetone or hot isopropanol and mixing with activated carbon; filtering the mixture, rinsing the filtration media with acetone or hot isopropanol, respectively, and condensing the filtrate to afford the product; and optionally, g) recrystallizing the solids from an alcohokwater solution.

13. A process for preparing 1 -(4-chlorobenzyl)-1 H-imidazole-4,5-dicarbonitrile comprising: a) reacting a solution of diaminomaleonitrile, DPGDME and formic acid in a reactor at about 40-50°C for about an hour, heating to about 135-140°C for about 3-4 hours while discarding solvent-water azeotropic distillate; b) cooling to about 50°C and heating to about 100°C under vacuum to collect solvent distillate; cooling to about 50°C and adding potassium bicarbonate and stirring for about an hour; c) adding 4-chlorobenzyl chloride, and optionally, MTBAC, and heating to about 100°C under vacuum for about 1 -2 hours and discarding solvent-water azeotropic distillate; d) heating to about 110-120°C for about 8 hours, cooling to about 50°C, heating to about 100°C under vacuum and collecting solvent distillate; e) cooling to about 50°C, adding water over about 30 minutes with stirring; f) filtering and rinsing the solids with water and heptane, drying the solids; g) dissolving the solids in acetone and adding activated carbon while mixing for about 24 hours at room temperature, filtering the solids and washing the solids with acetone and concentrating the solids in vacuo to afford 1-(4-chlorobenzyl)- 1 H-imidazole-4,5-dicarbonitrile; or dissolving the solids in hot isopropanol and mixing with activated carbon while stirring for about 24 hours at about 70°C, then filtering the hot mixture and washing with hot isopropanol, concentrating the filtrate in vacuo to afford 1 -(4-chlorobenzyl)-1 H-imidazole-4,5-dicarbonitrile; and optionally; h) recrystallizing the 1 -(4-chlorobenzyl)-1 H-imidazole-4,5-dicarbonitrile from an alcohokwater solution; wherein the alcohol is propanol or isopropanol.

14. The process for preparing 1 -(4-chlorobenzyl)-5-cyano-1 H-im idazole-4- carboxamide from 1 -(4-chlorobenzyl)-1 H-imidazole-4,5-dicarbonitrile prepared according to Claim 1 , 10, 12 or 13 wherein the 1-(4-chlorobenzyl)-1 H-imidazole-4,5- dicarbonitrile is added to concentrated sulfuric acid and stirred for about 16 hours at about 20-45°C or stirred for about an hour at about 80°C.

15. The process for preparing 1 -(4-chlorobenzyl)-5-cyano-1 H-imidazole-4- carboxamide from 1 -(4-chlorobenzyl)-1 H-imidazole-4,5-dicarbonitrile prepared according to Claim 1 , 10, 12 or 13 wherein the 1-(4-chlorobenzyl)-1 H-imidazole-4,5- d icarbonitrile is a) added to an alcohokwater solution with a base that is potassium hydroxide or sodium hydroxide and stirred for about 24 hours at about 65-80°C to afford the product; and wherein the alcohol is selected from the group consisting of methanol, ethanol, propanol, isopropanol and n-butanol; or b) added to isopropanokwater (1 :4) and an aqueous solution of potassium hydroxide to a sealed pressure flask, heated to about 90°C under about 10 psi nitrogen for about 30 minutes, then adding additional potassium hydroxide while heating at about 90°C for about 9 hours, cooling to room temperature, depressurizing, and filtering the mixture, washing the filtrate with isopropanokwater (1 :1 ) and drying to afford the product.