1 GB2179936A 1
SPECIFICATION
Cephalosporin salts and injectable compositions Summary Crystalline sulfuric, di-nitric, mono-hydrochloric, dihydrochloric, and di- and sesqui-orthosphosphoric acid addition salts of 7-[a-(2-aminothiazol-4-yi)-a-(Z)-methoxyamino-acetamidol-3-[(1-methyil-pyrrolidinio)-methyll-3-cephem-4-carboxylate are stable even at elevated temperatures. The crystalline sulfuric acid addition salt is made by forming an admixture of (a) at least one molar equivalent of sulfuric acid with (b) zwitterion in an amount so as to be present in the admixture 10 at a concentration of greater than 25 milligrams/mi, causing crystallization, separating the crystals, washing and drying. The crystalline monohydrochloride, dihydrochloride, and orthophosphate salts are prepared by dissolving the zwitterion in the appropriate amount of acid, causing crystallization by adding acetone and isolating the crystals. Physical admixtures of the salts with certain bases in proportions to give a pH ranging from about 3.5 to about 7 on dilution with water provide injectable compositions on dilution.
is Brief Description of the Drawing
Figure 1 is a graphical representation of the infra red absorption spectrum of crystalline 7-[a (2-aminothiazol-4-yi)-a-(Z)-methoxyiminoacetamidol-3-[(1 -methyl- 1 pyrrolidinio)methyi]-3-cephem-4- 20 carboxylate sulfate salt measured on a KBr dilution thereof.
Figure 2 is a graphical representation of the infra red absorption spectrum of the crystalline sesquiphosphate salt of 7-[a-(2-aminothiaziol-4-yi)-x-(Z)-methoxy- iminoacetamido]-3-[(1 -methyl1 - pyrrolidinio)-methyll-3-cephem-4-carboxylate measured on a KBr dilution thereof.
Figure 3 is a graphical representation of the infra red absorption spectrum of the crystalline 25 diphosphate salt of 7-[a-(2-aminothiazol-4-yl)-x-(Z)-methoxy- iminoacetamido]-3-[(1 -methyl- 1 -pyrroii dinio)-methyll-3-cephem-4-carboxylate measured on a KBr dilution thereof.
Technical Field
This invention is directed to temperature stable semi-synthetic cephalosporin salts whose 30 preparation has not been described in the literature, to the preparation of such salts, and to admixtures containing these salts.
Background of the Invention
Aburaki et a]. U.S. Patent No. 4,406,899 discloses 7-[a-(2-aminothiazol-4yi)-a-(Z)-methoximi- 35 noacetamidol-3-[(1 -methyl- 1 -pyrrolidinio)-methyll-3-cephem-4- carboxylate in the zwitterion form and mentions corresponding acid addition salts (which are present in the zwitterion form in injectable compositions) and shows that the zwitterion form has broader spectrum activity than ceftazidime and cefotaxime.
However, the aforementioned Aburaki et al. cephalosporins are stable only for a few hours as 40 injectable compositions and the zwitterion form even as a dry powder is unstable at room temperature and loses 30% or more of its activity on storage at elevated temperatures (e.g. 45 deg. C and above) for even one week and therefore requires special insulated packaging and/or refrigeration and is at a packaging and storage disadvantage compared to ceftazidime and cefotaxime.
While Aburaki et al. mentions acid addition salts, the patent does not state how to make these or state which if any of these salts have good stability in dry powder form. Kessler et al., -Comparison of a New Cephalosporin, 13MY 28142, with Other Broad-Spectrum fi-Lactam Anti biotics", Antimicrobial Agents and Chemotherapy, Vol. 27, No. 2, pp. 207216, February 1985 mentions the sulfate salt, but does not disclose how to prepare such or that this salt has room 50 temperature stability and good elevated temperature stability in dry powder form.
Summary of The Invention
It has been discovered herein that certain crystalline acid addition salts of 7-[a-(2-aminothiazol 4-yi)-a-(Z)-methoxyiminoacetamido)-3-[(1 -methyl1 -pyrrolidinio)- methyi]-3-cephem-4-carboxylate in 55 dry powder form have excellent room temperature stability and have superior elevated tempera ture stability compared to the zwitterioin form. The term---drypowder form- as used herein means a moisture content of less than 5% by weight.
These acid addition salts are the crystalline salts of 7-[a-(2aminothiazol-4-yl)-a-(Z)-methoxyimi- noacetamido-3-[(1 -methyl- 1 -pyrrolidinio)-methyl]-3-cephem-4- carboxylate selected from the group 60 consisting of the sulfuric, di-nitric, mono-hydrochloric, and dihydrochloric acid addition salts and orthophosphoric acid addition salts (1.5-2 moles of orthophosphoric acid per mole of salt, e.g. a range of from the sesqui- to the di-orthophosphoric acid salts), or solvates thereof. The term 11 crystalline- is used herein to mean at least some characterizing arrangement of molecules.
While the sulfuric, di-nitric, &hydrochloric and orthophosphoric acid addition salts herein are 2 GB2179936A 2 prepared in clearly crystalline form (as evidenced by birefringence under a polarizing microscope) with precise arrangement of molecules, the mono- hydrochloric acid addition salt has been prepared only with some regularity in the arrangement of its molecules (as evidenced. by poor birefringence under polarizing microscope) and not a precise predictable arrangement and thus is ---poorly-crystalline. The term "crystalline" is used herein to embrace not only the clearly crystalline salts but also the "poorly" appearing crystalline mono-hydrochloric acid addition salt.
The acid addition salts herein when formed into aqueous injectable compositions provide the zwitterion in solution. The zwitterion has the structure 10 CH2 -IN 0 -CH3 coo e 1) - - 1 15 CH3 The broad spectrum utility against various organisms of the zwitterion form, and thus of aqueous compositions made up from the salts herein, is shown by the data in Aburaki et al.
U.S. 4,406,899.
Aqueous compositions made up from the acid addition salts herein simply by the addition of sterile water provide acidic solutions which provoke unacceptable irritation on intravenous admin istration to rabbits and unacceptably painful sensation on intramuscular administration to rabbits.
The sulfuric acid and di- nitric acid addition salts have reduced solubilities which are insufficient for typical injectable compositions. It has been found herein that these objectionable character- 25 istics are overcome by utilizing the salts herein in physical admixture (that is as an admixture of solids) with a pharmaceutically acceptable non-toxic organic or inorganic base in proportions to provide a pH of about 3.5 to about 7 on dilution with water to a zwitterion activity of from 1 mg/mi to 400 mg/mi, normally 250 mg/mi (as determined by high performance liquid chromato graphy, hereinafter HPLC).
A preferred salt herein is the crystalline suifuric acid addition salt. It is preferred because its low solubility in water (25 mg/mi) allows high recovery from aqueous medium on crystallization.
The crystalline sulfuric acid addition salt is readily prepared by a process comprising the steps of (a) forming an admixture of (i) at least 1 molar equivalent of sulfuric acid and (ii) zwitterion in an amount so as to be present in the admixture at a concentration greater than 25 mglmi, (b) causing crystallization of the suffuric acid addition salt to occur, and (c) isolating crystalline sulfuric acid addition salt.
Detailed Description
The crystalline salts herein (hereinafter referred to simply as the salts herein) have excellent 40 stability at room temperature and have a potency loss (as determined by HPLC), of less than 1% on storage for a month at room temperature. These salts also have excellent stability at elevated temperatures and have a potency loss (as determined by HPLC) of less than 15% on storage for a month at 45-56 deg. C.
The sulfuric acid addition salt is a preferred salt herein. It has a potency loss of less than 10% 45 on storage for a month a 45-56 deg. C. Very importantly, it has a low solubility in water, i.e.
about 25 mg/mi, and therefore is crystallized from water with minimized residual loss.
The di-nitric acid addition salt herein also has a low solubility in water, i.e. about 60 mg/mi, and therefore also provides low residual loss on crystallization from water.
The mono-hydrochloric, &hydrochloric and sesqui-or di-orthophosphoric acid addition salts have water solubilities greater than 200 mg/mi., and therefore are preferably crystallized from organic solvents, rather than from water, in order to obtain good yields.
We turn now to the preparation of the salts herein.
As previously indicated the sulfuric acid addition salts herein is prepared by a process com- prising the steps of (a) forming an admixture of (i) at least one molar equivalent of sulfuric acid and (ii) zwitterion corresponding to said salt in an amount so as to be present in the admixture at a concentration of greater than 25 mglmi, (b) causing crystallization to occur, and (c) isolating crystalline sulfuric acid addition salt. Preferably the zwitterion is used in step (a) in an amount so as to be present in the admixture at a concentration ranging from about 100 mg/mi to about 200 mg/mi, and step (b) is carried out in an aqueous medium free of organic solvent. Normally 60 no more than 2 molar equivalents of sulfuric acid are utilized in step (a). Normally zwitterion is used in step (a) in an amount so as to be present in the admixture ata concentration less.than 500 mg/m].
Step (a) is-readily carried out either by adding solid zwitterion to sulfuric acid solution (e.g, 1N HSO,) with rapid stirring to form a solution. Alternatively step (a). can be carried by dissolving 65 -z; 3 GB2179936A 3 solid zwitterion in water and slowly adding sulfuric acid with stirring to form a solution.
Step (b) is carried out by inducing crystallization, preferably by seeding, and then slurrying, preferably for 15 minutes to 2 hours. It is preferred that this crystallization step be carried out in aqueous medium, free of organic solvent, and in such case purities greater than 98% are normally obtained. While the presence of organic solvent, such as acetone, fosters crystallization 5 and increases yield by lowering the solubility of the formed sulfuric acid addition salt in the crystallization medium, it also can foster precipitation of impurities resulting in decreased purity.
When the zwitterion is used in step (a) in an amount so as to be present in the admixture in an amount less than 25 mg/mi, organic solvent, preferably acetone, must be included in the crystallization medium to provide reasonable recovery. When acetone is used, it is appropriately 10 used in amounts of 0.5 to 10 volumes per volume of aqueous crystallization medium.
Step (c) is carried out by separating the crystals from the crystallization medium, preferably by vacuum filtration, then washing e.g. with acetonelwater followed by acetone alone or 0. 1 N sulfuric acid (e.g. 1/10 volume) followed by acetone (e.g. 1/4 volume), and then drying, e.g. by vacuum drying at 30-50 deg. C for 4-20 hours.
The method herein for forming the sulfuric acid addition salt results in the purification of the zwitterion form because of the limited solubility of the suffuric acid addition salt compared to the zwitterion form and can be used to purify zwitterion without isolating it as a solid. If it is desired to obtain substantially pure zwitterion (free-base) from the formed sulfuric acid addition salt, this can be carried out by dissolving the salt in water, adding Ba(OH),.8H,0 in an amount of 90-100% of theory at a pH of less than 6.5 to precipitate BaSQ, filtering to remove the BaSO, and recovering the filtrate containing the zwitterion dissolved therein and utilizing it as a solution or isolating solid zwitterion (free-base) by Iyophilizing it or by adding acetone to precipitate amorphous zwitterion followed by isolating solid zwitterion by vacuum filtration, washing e.g.
with acetone, and vacuum drying. Alternatively, the sulfuric acid addition salt is converted to the 25 free-base utilizing ion exchange resins, e.g. Dowex WGIR (a weak base anion exchange resin) and Dowex Xl-1- 40090.01 (a strong acid cation exchange resin) with subsequent lyophilization.
Turning now to the preparation of the crystalline di-nitric acid addition salt herein, this is obtained by admixing (i) at least two molar equivalents of nitric acid and (H) zwitterion corre- sponding to said salt so to be present in the admixture at a concentration greater than 100 mg/ml, and then inducing crystallization by seeding or rubbing with a glass rod, diluting with 2propanol and cooling. The crystalline di-nitric acid addition salt is recovered e.g. by filtering, washing sequentially, e.g. with 2-propanol-H,0 (50% vlv), 2- propanol, and ether, and then vacuum drying at 50 deg. C for 2 hours.
The mono-hydrochloric acid addition salt herein is prepared by dissolving zwitterion in approxi- 35 mately one molar equivalent of hydrochloric acid and causing crystallization by adding acetone with stirring and continuing to stir, followed by isolatng crystals, e.g. by vacuum filtration followed by washing with acetone and vacuum drying. Alternatively the mono-hydrochloric acid addition salt is formed from the &hydrochloric acid addition salt by slurrying the &hydrochloric acid addition salt in methylene chloride and adding 1 mole equivalent of triethylamine followed 40 by slurrying to form the mono-hydrochloric acid addition salt which is isolated, e.g. by vacuum filtration, followed by washing with methylene chloride and vacuum drying.
The crystalline di-hydrochloric acid addition salt herein is prepared by dissolving zwitterion in at least two molar equivalents of hydrochloric acid, then causing crystallization by adding ace tone, then isolating crystals e.g. by vacuum filtration, washing with acetone and vacuum drying. 45 The crystalline di-orthophosphoric acid addition salt herein is prepared by dissolving the zwit terion in at least 2 molar equivalents of phosphoric acid, causing crystallization by adding acetone, and isolating crystals by e.g. by vacuum filtration followed by washing first with acetone and then with ether and then vacuum drying. The crystalline sesqui-orthophosphoric acid addition salt is formed by this same procedure except that about 1.5 molar equivalents of 50 phosphoric acid is used.
The salts herein are formed into injectable compositions by diluting with sterile water and buffering to a pH of 3.5-7 to form an injectable concentration of 1 mg/mi up to 400 mg/mi of zwitterion. Suitable buffering agents include, for example, trisodium orthophosphate, sodium bicarbonate, sodium citrate, N-methyiglucamine, L(+) lysine and L(+) arginine. For intramuscular or intravenous administration to an adult human, a total dosage of from about 750 to about 3000 mg per day in divided doses is normally sufficient.
The salts herein are not desirably formed into injectable compositions simply by the addition of sterile water because the sulfuric and di-nitric acid addition salts are not sufficiently soluble to form compositions of normal concentration for administration and because the salts herein when 60 dissolved provide very low pH compositions (1.8-2.5) which provide painful sensation on injec tion. As indicated above, it has been found herein that these shortcomings are overcome by forming the salts herein into a physical, i.e. solid, admixture with pharmaceutically acceptable, normally solid non-toxic organic or inorganic bases in proportions to provide a pH ranging from about 3.5 to about 7, preferably from about 4 to about 6, on dilution of the admixture with 65 4 GB2179936A 4 water to injectable concentration of 1 mglmi up to 400 mg/mi of zwitterion, e.g. zwitterion activity of 250 mglml as determined by HPLC assay.
The exact proportions of ingredients in the physicaL admixture vary from lot to lot of the salt since the purity of the salt-varies from lot to lot. The proportions of ingredients are established for a particular lot by pretitrating in respect to a sample to obtain a selected pH within the.5 aforementioned range.
The physical admixture is readily stored and shipped in solid form thereby taking advantage of the stability of the salts herein and is readily converted into an injectable composition simply by addition by water, e.g. by a nurse or doctor, just prior to use.
The physical admixture is prepared by blending the salt and the base into a uniform blend, e.g. 10 utilizing a standard blender in a dry atmosphere, and is then preferably filled into a vial or other container, all under aseptic conditions.
The bases for use in the admixture include, for example, trisodium orthophosphate, sodium bicarbonate, sodium citrate, N-methyiglucamine, L(+ ) lysine and L(+) arginine. L(+) lysine and L(+) arginine are preferred since admixtures containing these are reconstituted to provide injectable compositions which on injection provide less pain in animals than compositions derived from admixtures containing other bases. The L(+) lysine is very preferably utilized in a proportion to provide a pH of 3.5-6 on dilution of the admixture with water to provide a composition with a zwitterion activity of 250 mg/mi (as determined by HPLC assay).
The salts herein and substantially dry physical admixtures containing them can be stored 20 without refrigeration or insulated packaging and still retain high potency.
In several of the preparations herein the unstable zwitterion is used as the starting material.
The preparation of this is described in Examples 1-3 of Aburaki et al. U. S. 4,406,899. The zwitterion is referred to in Aburaki et al. as 7-[(Z)-2-methoxyimino-2-(2- aminothiazol-4-yi)acetam- ido-3-[(1 -methyl- 1 -pyrrolidinium)methyll-3-cephem-4-carboxylate.
The invention is illustrated in the following working examples.
Example 1
Preparation of the Sulfuric Acid Addition Salt 1.5 g of zwitterion are added slowly to 10 mi of rapidly stirred 1N H,SO, (1.59 molar equivalents) at 20-26 deg. C. A solution is obtained. Crystallization is then induced by seeding with crystalline sulfuric acid addition salt and the crystalline mass is slurried for 0.5 hours. The crystals are then separated by vacuum filtration, washed with 3 mi of 50% acetone/water (V/V) and with two 5 mi portions of acetone, and vacuum dried at 40-50 deg. C. overnight.
A typical yield is 1.3 9 of sulfuric acid addition salt. Analysis: Calculated for C1.1---124N6O.S.M2SO4: %C, 39.44; %H, 4.53; %N, 14.52; %S, 16.62; %H,O, none. Found: %C, 38.91; %H, 4.57; %N, 14.64; %S, 16.71; %H201 1.42.
Example 11
Preparation of the Sulfuric Acid Addition Salt 1.5 g of zwitterion are dissolved in 5 mi of water. 5 mi of 1 M H2SO, are slowly added to this solution with stirring. Crystallization is then induced by seeding with crystalline acid addition salt and the crystalline mass is slurried for 0.5 hours. The crystals are then separated by vacuum 45 filtration, washed with 3 mi of 50% acetone/water (V/V) and with two 5 mi portions of acetone, and vacuum dried at 40-50 deg. C overnight.
A typical yield is 1.3 9 of sulfuric acid addition salt.
Example Ill
Preparation of the (HNO,), Acid Addition Salt 300 mg of zwitterion are dissolved in 2N nitric acid (0.5 mi). The solution is rubbed with a glass rod, diluted with 2-propanol (0.4 mi) and cooled. The crystalline title compound is col- lected and is sequentially washed with 0.4 m] of 2-propanol H,0 (1:1), 2- propanol and then 55 ether to afford 127 mgs of the dinitrate salt.
Analysis: Calculated for CH14N,0,S,21-INO,: %C, 37.62; %H, 4.32; %N, 18. 47; %S, 10.57.
Found. %C, 36.92; %H, 4.10; %N, 18.08; %S, 10.67; (H,0 content 0.90%).
Example IV
Preparation of the Monohydrochloride Acid Addition Salt 1 9 of zwitterion is dissolved in 2.08 mi of 1N HCl (1 molar equivalent) at 20-25 deg. C. Thirty mi of acetone are added with rapid stirring over a 15 minute period whereby crystals 65 form. Stirring is continued for 1 hour. The crystals are isolated by vacuum filtration, washed with 65 GB2179936A 5 -1, m] of acetone and vacuum dried at 50 deg. C for 2 hours.
A typical yield is 0.9 g of crystalline monohydrochloride salt. Analysis: Calculated for C,,H2,NIOIS2.HCl: %C, 41.37; %H, 4.75; %N, 15.2; %S, 11.63; %Cl, 12.86. Found: %C, 39.32; %H, 4.88; %N, 13.95; S, 11.28; %Cl, 12.44; %H,O, 4.5. (Corrected for H20: %C, 5 41.17; %N, 14.61; %S, 11.82; %Cl, 13.03).
Example V
Preparation of the Whydrochloride Acid Addition Salt and Preparation of the Monohydrochloride 10 Acid Addition Salt From It 350 mg of zwitterion are dissolved in 2 m] of IN-HO. 10 mi of acetone are added to the resultant solution, with rapid stirring and over a 5 minute interval, whereby crystals form. Stirring is continued for 5 additional minutes. Then 10 additional m] of acetone are added and stirring is carried out for 0.5 hours. The crystals are removed by vacuum filtration, washed with two 5 mi portions of acetone and vacuum dried at 40-45 deg. C for 24 hours.
A typical yield is 300 mg of crystalline dihydrochloride acid addition salt. Analysis calculated for C,,H2,N,O,S2.2HCI: %C, 41.38; %H, 4.75; %N, 15.2; %S, 11.62; %Cl, 12. 8. Found: %C, 40.78; %H, 4.98; %N, 143; %S, 11.25; %H,O, 1.25. (Corrected for HO: %C, 41.11; %N, 14.88; %S, 11.39; %Cl, 11.94).
1 g of dihydrochloride salt prepared as above is slurried in 20 mi of methylene chloride at 20 20-25 deg. C in a sealed flask and 0.28 m] of triethylamine is added over a 15 minute interval.
The crystalline mass is then slurried for 5 hours. The resultant monohydrochloride crystals are then isolated by vacuum filtration, washed with two 5 mi portions of methylene chloride and vacuum dried at 50 deg. C for 2 hours. A typical yieldis 800 mg.
Example V1
Preparation of the Di-orthophosphoric Acid Addition Salt 1 9 of zwitterion is dissolved in 3.4 mi of 144 mg/mi H3PO, (2.2 molar equivalents) at 15 deg. C. The resulting solution is suitably filtered to clarify it. 12 mi of acetone are added to the 30 clarified solution, with rapid stirring and over a 10 minute period, whereby crystals form. Stirring is continued for 10 minutes. Then 30 mi of acetone are added over a 10 minute period, and stirring is continued for an additional 15 minutes. The crystals arecollected by vacuum filtration, washed with two 5 mi portions of acetone and two 5 mi portions of ether and dried under high vacuum for 16 hours.
A typical yield for this type of preparation was 1.1 g of crystalline diorthophosphoric acid addition salt. Analysis: Calculated for C,,,H,,,N,,0,S,.2H,PO,,: %C, 33. 72; %H, 4.47; %N, 12.42.
Found: %C, 33.43; %H, 4.65; %N, 12.02; %H,O, 1.82. (Corrected for H20%C, 34.0; %N, 12.2).
The sesqui-orthophosphoric acid addition salt is formed as above except that 1.5 molar 40 equivalents of H,PO, are used instead of 2.2 molar equivalents.
Example VIl
Stabilities at Elevated Temperatures Elevated temperature stabilities were determined by storing the preparations in dry containers at temperatures and for time periods as denoted below and potency losses or gains were determined by HPLC. A % potency gain is indicated by a plus sign in front of a figure. A less than 10% potency loss over a 2 to 4 week period at 45-56 deg. C is usually indicative of less than 10% potency loss over a 2-3 year period at room temperature.
6 GB2179936A 6 PERCENT LOSS Deq. C 56 Deg. C 20o Deo. 5 (Wwks) (Weeks) (Days) 2 1 4 6 1 2 4 Zwitterion 37 51 71 - 57 - 10 m 2 so 4 salt 2.4 to 5 3 +5 1.4 5 to 46 3 0 to 6 0-10 (HNO3)2 salt 8.8 3.4 0.68 10.3 3.7 2.4 MC1 salt 4.0 2.3 6.0 6.4 6.4 - - - (BC1) 2 salt 0 - 7.4 - 0 - 7.2 12.4 20 (m 3 PO 4)2 salt D 3.0 1.0 - L2.7 5.0 - - Example V111
Testing of Physical Admixtures Physical admixtures were made up of crystalline sulfuric acid salt with (a) trisodium orthophos- 30 phate, (b) sodium bicarbonate, (c) L(+) lysine, and (d) L(+) arginine. The bases were added in proportions to provide pH's on dilution of the admixture with water to a zwitterion activity of 250 mg/mf (as determined by HPLC assay) as follows: trisodium orthophosphate (to provide a pH of 6.0); sodium bicarbonate (to provide a ph of 6.0),- L(+) lysine (to provide a pH of 6.0); L(+) arginine (to provide a pH of 6.0). Injectable compositions were made up by reconstituting 35 with sterile water to a zwitterion activity of 250 mg/mi as determined by HPLC assay. There were no solubility problems. Injections (100 mg/kg) were carried out intramuscularly on rabbits with pain within acceptable thresholds. The least pain was with the arginine containing compo sition.
Similar results of good solubility and acceptable pain on intramuscular injection are obtained on 40 use of the other salts herein in the physical admixtures with the above bases.
Fig. 1 is the infra red absorption spectrum of the crystalline sulfate salt prepared as described in Examples 1 or 11 pelletized in the crystalline form with potassium bromide.
The X-ray powder diffraction pattern of the crystalline sulfate salt of 7[a-(2-aminothiazol-4-yi) a-(z)-methoxyiminoacetamidol-3-[(1 -methyl- 1 -pyrrolidinio)-methyll-3- cephem-4-carboxylate prepared 45 as described in Example 1 or 11 was determined with a Rigaku Powder Diffractometer using a copper target X-ray tube, a nickel filter, and the sample contained in a glass dish. The scan rate was 2 deg./min. over the. range from 5 deg. to 40 deg. and a chart was mechanically recorded to show the angles of maximum diffraction. From this the (d) spacings and relative intensities (I/lo) were calculated. They are listed below.
d spacing (A) 9.20 6.80 5.50 5.09 4.50 4.41 4.19 3.78 3.64 3.39 3.31 3.15 1/10 ( 100 50 28 22 38 44 63 38 44 25 31 47 7 GB2179936A 7 EXAMPLE IX
PREPARATION OF THE SESQUIPHOSPHATE SALT The zwitterion, 0.70 g., is dissolved with rapid stirring in from 2.2 to 2.4 mi. of 85% phosphoric acid (2.1 to 2.2 molar equivalents) which has been diluted 1:10 (v/v) with water.
The solution is clarified by filtration through a 0.22-0.45 micron-pore size membrane filter. From to 7 parts by volume (15-20 ml) of methanol is added to the filtrate with rapid stirring during a 30 to 60 min. period. Crystals form during this operation, and rapid stirring is continued for 1.5 to 2 hours. The crystalline product is recovered by vacuum filtration. The product is washed on the filter first with 6 to 8 mi of 1:1 (v/v) methanotacetone taking care to maintain a tightly 10 packed filter cake, and then with acetone. The product is dried in vacuo at 50 C for 2 hours; typical yield 0.7 to 0.75 g.
Infrared Interpretation (see Fig. 2) (IR, KBr pellet) Peak Position (cm-1) Functional Group 2800-3400 NH,NH,+, carboxyl OH 1780 P-factam C=0 1680 Carboxyl C=0 1660 Amide C=0 1630 C=N, C=C 1550 Amide OH 980,1040 POj Behavior On Heating An exotherm is shown at 171.8C in the differential scanning calorimeter tracing.
X-Ray Diffraction Pattern The X-ray powder diffraction pattern of the foregoing sesquiphosphate salt was measured with a Rigaku Powder Diffractometer in the same fashion as described above with respect to suffate 30 salt with the following results.
d 1/10 11.04 - 32 9.2 - 16 35 7.89 - 24 7.02 - 42 6.7 - 32 5.5 - 26 4.64 100 40 4.456 - 53 4.3 - 58 3.88 - 26 3.75 89 3.56 - 21 45 3.31 - 26 3.05 16 NIVIR Interpretation ('H 90 MHz NIVIR, D20 solution);;n H,..'OCH3 H 7 6 12 2 13 16Y.15, 3 131 8 GB2179936A 8 Chemical Shift Ippm, d vs. T5f) Description Integral Assignment
2.0-2.4 Multiplet 4 14CH, WC1-12 3.04 Singlet 3 12CH, 5 3.3-3.6 Multiplet 5 2CH, 13CH2, lYCH, 3.94 Doublet 1 2CH 4.12 Singlet 3 20CH3 4.12 Doublet 1 11CH 4.8 Doublet 1 11CH 10 5.42 Doublet 1 6CH 5.88 Doublet 1 7M 7.21 Singlet 1 18CH 15 Stability Time- Temperature % Loss 1 day; 1 OOOC - 10.9 3 days; 700C - 0 20 7 days; 700C - 1.9 1 week; 560C - 1.0 2 weeks; 560C 1.4 4 weeks; 560C - 0 1 week; 450C - 0 25 2 weeks; 450C - 1.4 4 weeks; 450C - 0.7 8 weeks; 450C - 1.6 1 month; 370C - 2.5 30 Elemental Analysis (percent by weight) Found Dry Basis Theory (Sesquiphosphate) c 35.44 36.3 36.4 H 4.66 4.41 4.7 35 N 12.88 13.2 13.4 H,0 2.29 - monohydrate=2.8% H20 H3P0,1 23.06 23.6 23.6 Karl Fischer Method