USH1696H - Process for making sulfonyl isocyanates - Google Patents

Process for making sulfonyl isocyanates Download PDF

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Publication number
USH1696H
USH1696H US08/793,188 US79318897A USH1696H US H1696 H USH1696 H US H1696H US 79318897 A US79318897 A US 79318897A US H1696 H USH1696 H US H1696H
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United States
Prior art keywords
phosgene
reaction
reaction mixture
sulfonamide
reactor
Prior art date
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Abandoned
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US08/793,188
Inventor
David Akueteh Adjei
Charles T. Blaisdell
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EIDP Inc
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EI Du Pont de Nemours and Co
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Publication date
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Priority to US08/793,188 priority Critical patent/USH1696H/en
Priority claimed from PCT/US1995/008966 external-priority patent/WO1996006826A1/en
Assigned to E.I. DU PONT DE NEMOURS AND COMPANY reassignment E.I. DU PONT DE NEMOURS AND COMPANY ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: ADJEI, DAVID AKUETEH, BLAISDELL, CHARLES T.
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Publication of USH1696H publication Critical patent/USH1696H/en
Abandoned legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D333/00—Heterocyclic compounds containing five-membered rings having one sulfur atom as the only ring hetero atom
    • C07D333/02—Heterocyclic compounds containing five-membered rings having one sulfur atom as the only ring hetero atom not condensed with other rings
    • C07D333/04—Heterocyclic compounds containing five-membered rings having one sulfur atom as the only ring hetero atom not condensed with other rings not substituted on the ring sulphur atom
    • C07D333/26—Heterocyclic compounds containing five-membered rings having one sulfur atom as the only ring hetero atom not condensed with other rings not substituted on the ring sulphur atom with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
    • C07D333/38—Carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C311/00—Amides of sulfonic acids, i.e. compounds having singly-bound oxygen atoms of sulfo groups replaced by nitrogen atoms, not being part of nitro or nitroso groups
    • C07C311/65—N-sulfonylisocyanates
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D403/00—Heterocyclic compounds containing two or more hetero rings, having nitrogen atoms as the only ring hetero atoms, not provided for by group C07D401/00
    • C07D403/02—Heterocyclic compounds containing two or more hetero rings, having nitrogen atoms as the only ring hetero atoms, not provided for by group C07D401/00 containing two hetero rings
    • C07D403/04—Heterocyclic compounds containing two or more hetero rings, having nitrogen atoms as the only ring hetero atoms, not provided for by group C07D401/00 containing two hetero rings directly linked by a ring-member-to-ring-member bond

Definitions

  • the present invention pertains to an improved process for making sulfonyl isocyanates from the corresponding sulfonamides and phosgene.
  • Sulfonyl isocyanates are useful intermediates in the preparation of fine chemicals such as pesticides, including sulfonylurea herbicides, and pharmaceuticals.
  • U.S. Pat. No. 4,238,621 discloses the preparation of sulfonyl isocyanates from a reaction mixture of the corresponding sulfonamides and phosgene wherein the sulfonamide is generally present in molar excess in the reaction mixture relative to phosgene.
  • the phosgene is always in molar excess relative to sulfonamide, thereby providing better yield and shorter reaction times.
  • the present invention pertains to an improved process for the preparation of sulfonyl isocyanates of Formula I comprising adding the corresponding sulfonamide of Formula II in small increments or continuously, perferably continuously, to a reaction mixture comprising inert solvent, phosgene and catalyst according to equation 1 ##STR1## such that there is in the reaction mixture an excess of phosgene relative to sulfonamide.
  • the most preferred sulfonyl isocyanate is methyl 2-(isocyanatosulfonyl)benzoate.
  • sulfonamide II is fed to a reaction mixture of inert solvent, catalyst and phosgene wherein it is converted to isocyanate I.
  • Elevated temperatures typically in the range of 100° to 200° C., preferably 120° to 135° C., are usually required to make the reaction proceed at practical rates.
  • Pressure can be ambient up to about 2 atmospheres (about 200 kPa).
  • Phosgene is replenished to the reaction mixture so that at any point during the reaction there is always present a molar excess of phosgene (hereinafter referred to as "phosgene-rich”) relative to sulfonamide; preferably there is at least 2% by weight of phosgene in the reaction mixture, more preferably at least 5%.
  • Sulfonamide can be fed to the reaction mixture in small increments or continuously, preferably continuously, and can be in the form of a slurry or solution in solvent, preferably as concentrated as possible. The slurry can be preheated before admission to the reactor.
  • Solvent can be any inert solvent with a boiling point at or above the desired reaction temperature; examples include xylene, chlorobenzene, mesitylene, toluene, pentachloroethane and octane.
  • Catalysts include (U.S. Pat. No. 4,238,621) carbaryl isocyanates such as butyl isocyanate and tertiary amines such as 1,4-diaza 2,2,2!bicyclooctane (DABCO).
  • carbaryl isocyanates such as butyl isocyanate
  • tertiary amines such as 1,4-diaza 2,2,2!bicyclooctane (DABCO).
  • DABCO 1,4-diaza 2,2,2!bicyclooctane
  • Catalysts also include sulfonyl isocyanates (Res. Discl. (1983) 23210, 261), preferably the product sulfonyl isofonyl isocyanate.
  • the sulfonyl isocyanate need not be isolated, and a small portion of the product reaction mixture (referred to as a "heel") from a previous batch can be employed as catalyst in a subsequent batch.
  • the reaction of sulfonamide and phosgene is very rapid and exothermic, and HCl is generated as a byproduct. It is preferable to drive the HCl out of the reaction mixture as rapidly as possible, preferably by maintaining vigorous reflux of phosgene, so that side-reactions caused by the HCl, and the resulting yield losses, are minimized.
  • the HCl off-gas will typically be captured by scrubbers so as to avoid release to the environment; the phosgene can be condensed and returned to the reaction mixture.
  • the HCl generation can be used to monitor the course of the reaction and can also be used to maintain an appropriate sulfonamide feed rate and concentration so that the reaction is kept under control and reaction times are as short as possible.
  • phosgene and dissolved HCl can be removed from the mixture by standard methods such as distillation.
  • the sulfonyl isocyanate can be recovered by standard methods, such as crystallization and filtration.
  • the sulfonyl isocyanate can be reacted further, with or without isolation, to form, for example, a sulfonylurea herbicide as described in U.S. Pat. No. 4,238,621, column 5, lines 14-20.
  • the critical feature of the present invention is the reaction of sulfonamide in a phosgene-rich environment throughout substantially the entire process.
  • known methods for producing sulfonyl isocyanate from sulfonamide add phosgene to a reaction mixture of sulfonamide such that throughout substantially the entire reaction the sulfonamide is in excess relative to phosgene.
  • Comparative Example A is provided as an illustration of the state of the art as disclosed in U.S. Pat. No. 4,238,621 and Res. Discl. (1983) 23210, 261. The same reactor was employed throughout.
  • the sulfonyl isocyanate is methyl 2-(isocyanatosulfonyl)benzoate and the sulfonamide is methyl 2-(aminosulfonyl)-benzoate.
  • the reactor is a Pfaudler 7500 L reactor which was jacketed for steam heating and which was equipped with a reflux condenser capable of cooling to -30° C. to recover refluxing phosgene.
  • the reactor has an inlet port for admitting reactants, an exit port for recovering product and an agitator for thorough mixing of ingredients during reaction.
  • a heel from a previous batch was present in the reactor.
  • a slurry of xylene and sulfonamide was made in a separate vessel.
  • the reactor was heated to about 130° C. after which phosgene was added until the reactor mixture was saturated with same (about 3% by weight of the reaction mass) at 127° C.
  • phosgene was added until the reactor mixture was saturated with same (about 3% by weight of the reaction mass) at 127° C.
  • continuous feed of sulfonamide slurry and butyl isocyanate was started simultaneously.
  • the slurry feed rate was 2 kG/min; the butyl isocyanate rate was about a 10% molar ratio relative to sufonamide and was maintained throughout the entire course of slurry addition.
  • the operating pressure was monitored as an indication of HCl off-gas generation.
  • Example 2 was run as described in Example 1 except using the quantities and conditions noted in the summary above.
  • Example 3 was run as described in Example 1 except using the quantities and conditions noted in the summary above.
  • a heel from a previous batch was present in the reactor.
  • the sulfonamide was slurried with xylene in a separate vessel and then the entire charge was transferred to the reactor containing the heel.
  • the butyl isocyanate was then added to the reactor after which the reactor was brought up to reaction temperature.
  • the continuous phosgene feed was then started at a rate of about 150 kG/hr, and adjusted as necessary to maintain a steady operating pressure as HCl is generated.
  • the reaction was complete, as indicated by the cessation of phosgene consumption, the residual HCl and phosgene was stripped from the reaction mixture by solvent distillation and by sparging with nitrogen under reflux and as the reaction mixture cooled.
  • the reaction mixture was analyzed for sulfonyl isocyanate and the yield calculated.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Abstract

PCT No. PCT/US95/08966 Sec. 371 Date Feb. 21, 1997 Sec. 102(e) Date Feb. 21, 1997 PCT Filed Jul. 21, 1995 PCT Pub. No. WO96/06826 PCT Pub. Date Mar. 7, 1996This invention relates to an improved method of making sulfonyl isocyanates from the corresponding sulfonamides and phosgene.

Description

BACKGROUND OF THE INVENTION
The present invention pertains to an improved process for making sulfonyl isocyanates from the corresponding sulfonamides and phosgene. Sulfonyl isocyanates are useful intermediates in the preparation of fine chemicals such as pesticides, including sulfonylurea herbicides, and pharmaceuticals.
U.S. Pat. No. 4,238,621 discloses the preparation of sulfonyl isocyanates from a reaction mixture of the corresponding sulfonamides and phosgene wherein the sulfonamide is generally present in molar excess in the reaction mixture relative to phosgene. In the present invention, the phosgene is always in molar excess relative to sulfonamide, thereby providing better yield and shorter reaction times.
SUMMARY OF THE INVENTION
The present invention pertains to an improved process for the preparation of sulfonyl isocyanates of Formula I comprising adding the corresponding sulfonamide of Formula II in small increments or continuously, perferably continuously, to a reaction mixture comprising inert solvent, phosgene and catalyst according to equation 1 ##STR1## such that there is in the reaction mixture an excess of phosgene relative to sulfonamide.
The most preferred sulfonyl isocyanate is methyl 2-(isocyanatosulfonyl)benzoate.
DETAILED DESCRIPTION OF THE INVENTION
According to the present invention, sulfonamide II is fed to a reaction mixture of inert solvent, catalyst and phosgene wherein it is converted to isocyanate I. Elevated temperatures, typically in the range of 100° to 200° C., preferably 120° to 135° C., are usually required to make the reaction proceed at practical rates. Pressure can be ambient up to about 2 atmospheres (about 200 kPa). Phosgene is replenished to the reaction mixture so that at any point during the reaction there is always present a molar excess of phosgene (hereinafter referred to as "phosgene-rich") relative to sulfonamide; preferably there is at least 2% by weight of phosgene in the reaction mixture, more preferably at least 5%. Sulfonamide can be fed to the reaction mixture in small increments or continuously, preferably continuously, and can be in the form of a slurry or solution in solvent, preferably as concentrated as possible. The slurry can be preheated before admission to the reactor.
Solvent can be any inert solvent with a boiling point at or above the desired reaction temperature; examples include xylene, chlorobenzene, mesitylene, toluene, pentachloroethane and octane.
Catalysts include (U.S. Pat. No. 4,238,621) carbaryl isocyanates such as butyl isocyanate and tertiary amines such as 1,4-diaza 2,2,2!bicyclooctane (DABCO). The full charge of catalyst can be added to the initial reaction mixture, or added incrementally or continuously during the course of reaction. Feeding the catalyst over the course of the reaction can reduce the total amount of catalyst needed and reduce side reactions.
Catalysts also include sulfonyl isocyanates (Res. Discl. (1983) 23210, 261), preferably the product sulfonyl isofonyl isocyanate. The sulfonyl isocyanate need not be isolated, and a small portion of the product reaction mixture (referred to as a "heel") from a previous batch can be employed as catalyst in a subsequent batch.
The reaction of sulfonamide and phosgene is very rapid and exothermic, and HCl is generated as a byproduct. It is preferable to drive the HCl out of the reaction mixture as rapidly as possible, preferably by maintaining vigorous reflux of phosgene, so that side-reactions caused by the HCl, and the resulting yield losses, are minimized. The HCl off-gas will typically be captured by scrubbers so as to avoid release to the environment; the phosgene can be condensed and returned to the reaction mixture. The HCl generation can be used to monitor the course of the reaction and can also be used to maintain an appropriate sulfonamide feed rate and concentration so that the reaction is kept under control and reaction times are as short as possible.
Once the reaction is complete, excess phosgene and dissolved HCl can be removed from the mixture by standard methods such as distillation. The sulfonyl isocyanate can be recovered by standard methods, such as crystallization and filtration. Alternatively, the sulfonyl isocyanate can be reacted further, with or without isolation, to form, for example, a sulfonylurea herbicide as described in U.S. Pat. No. 4,238,621, column 5, lines 14-20.
In accordance with this invention, improved yields of sulfonyl isocyanate are obtained with less reaction time. The critical feature of the present invention is the reaction of sulfonamide in a phosgene-rich environment throughout substantially the entire process. In contrast, known methods for producing sulfonyl isocyanate from sulfonamide add phosgene to a reaction mixture of sulfonamide such that throughout substantially the entire reaction the sulfonamide is in excess relative to phosgene.
EXAMPLES
The examples which follow demonstrate the improved process of the present invention. Comparative Example A is provided as an illustration of the state of the art as disclosed in U.S. Pat. No. 4,238,621 and Res. Discl. (1983) 23210, 261. The same reactor was employed throughout. In all examples the sulfonyl isocyanate is methyl 2-(isocyanatosulfonyl)benzoate and the sulfonamide is methyl 2-(aminosulfonyl)-benzoate.
The reactor is a Pfaudler 7500 L reactor which was jacketed for steam heating and which was equipped with a reflux condenser capable of cooling to -30° C. to recover refluxing phosgene. The reactor has an inlet port for admitting reactants, an exit port for recovering product and an agitator for thorough mixing of ingredients during reaction.
______________________________________                                    
Summary of Ingredients and Parameters                                     
          Example 1                                                       
                 Example 2                                                
                          Example 3                                       
                                   Example A                              
______________________________________                                    
Sulfonamide (kG)                                                          
            771.8    1452.8   1589   771.8                                
Butyl isocyanate (kG)                                                     
            32       72.6     72.6   71.7                                 
Xylene (kG) 2679     2679     2679   2679                                 
*Heel (kG)  898.9    911.6    961.6  972.5                                
Reaction Temperature                                                      
            126-130  126-130  126-130                                     
                                     126-130                              
(°C.)                                                              
Reaction time (hours)                                                     
            2.5      7.2      7.5    3.4                                  
% yield sulfonyl                                                          
            95.1     94.4     95.1   87.7                                 
isocyanate (based                                                         
on sulfonamide)                                                           
______________________________________                                    
 *Heel is comprised of sulfonyl isocyanate and solvent, and is the product
 reaction mixture from a previous batch.
Example 1
A heel from a previous batch was present in the reactor. A slurry of xylene and sulfonamide was made in a separate vessel. The reactor was heated to about 130° C. after which phosgene was added until the reactor mixture was saturated with same (about 3% by weight of the reaction mass) at 127° C. While maintaining vigorous reflux conditions, continuous feed of sulfonamide slurry and butyl isocyanate was started simultaneously. The slurry feed rate was 2 kG/min; the butyl isocyanate rate was about a 10% molar ratio relative to sufonamide and was maintained throughout the entire course of slurry addition. The operating pressure was monitored as an indication of HCl off-gas generation. During the course of the reaction, phosgene was replenished to the reactor as needed to maintain reaction temperature and so that the reaction mixture was always saturated with same. When the reaction was complete, the residual HCl and phosgene was stripped from the reaction mixture by solvent distillation and by sparging with nitrogen under reflux and as the reaction mixture cooled. The reaction mixture was analyzed for sulfonyl isocyanate and the yield calculated.
Example 2
Example 2 was run as described in Example 1 except using the quantities and conditions noted in the summary above.
Example 3
Example 3 was run as described in Example 1 except using the quantities and conditions noted in the summary above.
Comparative Example A
A heel from a previous batch was present in the reactor. The sulfonamide was slurried with xylene in a separate vessel and then the entire charge was transferred to the reactor containing the heel. The butyl isocyanate was then added to the reactor after which the reactor was brought up to reaction temperature. The continuous phosgene feed was then started at a rate of about 150 kG/hr, and adjusted as necessary to maintain a steady operating pressure as HCl is generated. When the reaction was complete, as indicated by the cessation of phosgene consumption, the residual HCl and phosgene was stripped from the reaction mixture by solvent distillation and by sparging with nitrogen under reflux and as the reaction mixture cooled. The reaction mixture was analyzed for sulfonyl isocyanate and the yield calculated.

Claims (4)

We claim:
1. In a process for making a compound of the formula
J--SO.sub.2 NCO
wherein
J is ##STR2## by reacting a compound of the formula J--SO2 NH2 with phosgene in a reaction mixture comprising the compound J--SO2 NH2, phosgene and a solvent, the improvement comprising conducting the reaction in the presence of a molar excess of phosgene relative to the compound J--SO2 NH2.
2. The process of claim 1 wherein the percent by weight of phosgene in the reaction mixture is at least 2%.
3. The process of claim 2 wherein the percent by weight of phosgene in the reaction mixture is at least 5%.
4. The process of claim 1 wherein J is J-1.
US08/793,188 1995-07-21 1995-07-21 Process for making sulfonyl isocyanates Abandoned USH1696H (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US08/793,188 USH1696H (en) 1995-07-21 1995-07-21 Process for making sulfonyl isocyanates

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
PCT/US1995/008966 WO1996006826A1 (en) 1994-08-29 1995-07-21 Improved process for making sulfonyl isocyanates
US08/793,188 USH1696H (en) 1995-07-21 1995-07-21 Process for making sulfonyl isocyanates

Publications (1)

Publication Number Publication Date
USH1696H true USH1696H (en) 1997-11-04

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
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Country Status (1)

Country Link
US (1) USH1696H (en)

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Owner name: E.I. DU PONT DE NEMOURS AND COMPANY, DELAWARE

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:ADJEI, DAVID AKUETEH;BLAISDELL, CHARLES T.;REEL/FRAME:008529/0806

Effective date: 19950802

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