KR960007802B1 - Process for the preparation of organic isocyanate with dihalotripheny phospholan - Google Patents

Abstract

The diphenylmethane diisocyanate(MDI), i.e. the intermediate of polyurethane or isocyanate manufacturing, is prepared by the method which does not use the phosgen gas. The preparation method is that dibromotriphenyl phospholan or dichlorotriphenyl phospholan is reacted with aliphatic or aromatic hydroxamic acid at the presence of tertiary amine at minus 40-150 deg. C. The benzohydroxamic acid 13.6 gram and dibromotriphenyl phospholan 42.2 gram is dissolved in a dichloromethane anhydride solvent, agitated and 20 ml of triethylamine is added slowly. After agitating for 30 Min., the solvent is removed by distillation and 9.3 gram of phenyl isocyanate is obtained.

Description

Process for preparing organic isocyanate using dihalotriphenylphosphorane

The present invention is to prepare isocyanate used to synthesize anguinine, which is a physiologically active substance such as diphenylmethane diisocyanate (hereinafter referred to as MDI), which is an intermediate in the manufacture of polyurethanes. Reaction of Dibromotriphenyl Phospholan or Dichlorotriphenyl Phospholan with aliphatic or aromatic hydroxamic acid in the presence of tertiary amines without the use of highly toxic and corrosive phosgene gases To produce an organic isocyanate.

To date, it is known that isocyanates are synthesized via various reaction routes. For example, first, a method of synthesizing isocyanates from substitution reaction of haloalkyl and silvercyanate (Arch. Pharmacol., 302, 617 (1969)). In this case, an isocyanate can be synthesized from haloalkyl, but has the disadvantage that an isocyanate cannot be synthesized from haloaryl.

Second, the preparation of isocyanates by carbonylation of nitroalkyl (US Pat. Nos. 3,461,149, 3,673,827) requires high temperatures of 100-200 ° C. and high pressures of 100-250 atm.

Third, the classical process for preparing isocyanates by phosgene gas of amines (British patent 1,086,782) is not only highly corrosive and toxic but also requires high reaction temperatures.

Fourth, the preparation method of isocyanate by Curtius Rearrangement (J. Org. Chem., 38, 2982 (1973)) is a carbonyl alumina made from the reaction of carbonyl chloride and azide. The method of preparing isocyanate by heating or applying light to the jide has the risk of explosion due to the heating of organic or inorganic azide.

Fifth, the method for preparing isocyanate by thermal decomposition of ester of carbamic acid (US Pat. No. 3,465,024) has a disadvantage of requiring a high temperature of 100 to 500 ° C. and low yield.

Sixth, there is a method for producing isocyanate by Rosen rearrangement. This method easily converts into amines, with little of the reaction stopping at the isocyanate stage. For this reason, many isocyanates show considerably lower yields even if they are not or are produced by the Rosene potential reaction. Methods have been devised to improve the problem of isocyanate production by such Rosene potential reaction. For example, first, there is a method of adding phosgene or thionylchloride to hydroxamic acid and a metal salt (US Pat. No. 2,394,597). However, this method also shows low yields and is not a practical technique because of its corrosiveness and toxicity. Reaction by dulceb, hydroxyxamic acid and diketene (J. Org. Chem., 26, 782 (1961)) is a high yield and corrosive method for producing isocyanate by pyrolysis of the resulting acetoacetate. There is no, but the high half of about 400 ℃ temperature is required.

The present invention provides a high yield of aliphatic or aromatic isocyanates by reacting dibromotriphenyl phosphoran or dichlorotriphenyl phosphoran and hydroxamic acid in the presence of tertiary amines at relatively low temperatures of -40 ° C to 150 ° C. Can be characterized.

Scheme (1) and reaction mechanism (2) of the present invention are as shown and isocyanate is produced through a potential reaction via a nitrene intermediate.

Specifically, hydroxamic acid and dibromotriphenyl phosphoran or dichlorotriphenyl phosphoran are dissolved in anhydrous reaction solvent, triethylamine is added, the reaction is carried out, the solvent is removed and distillation under reduced pressure is performed to obtain isocyanate. This isocyanate was analyzed as a stable urea substance by reacting with an amine because the reaction is large.

Any tertiary amine used in this reaction can be used. Triethyl amine, pyridine, quinoline and quinoxaline, hexamethylenetetramine, 1,4-diazabicyclo [2. 2. 2.] octane (1. 4) Diazabicyclo [2. 2. 2] Octane), 1, 5- diazabicyclo [4. 3. 0] non-5-ene (1, 5-Diazabicyclo [3. 0] non-5-ene), 1,8-diazabicyclo [5. 4. 0] undec-7-ene (1,8-Diazabicyclo [5.4.0] undec-7-ene) is particularly effective. This reaction can be either bulk or solution reaction, but any solvent except protic solvent can be used as a solvent. Dichloromethane, chloroform , Acetonitrile, diethyl ether and the like are useful. At this time, the reaction temperature is preferably reacted in the temperature range of -40 ℃ to 150 ℃, especially the temperature range of 0 ℃ to 100 ℃.

The present invention will be described in detail as examples. However, the present invention is not limited to this embodiment.

Example 1

13.6 grams of benzohydroxamic acid and 42.2 grams of dibromotriphenyl phosphoran were added to a 500 milliliter three-necked flask containing 200 ml of anhydrous dichloromethane, and 20 ml of triethylamine was slowly added. After stirring for 30 minutes, the solvent was distilled off, and distillation under reduced pressure was carried out to react phenylisocyanate (Phenylisocyanate) with 9.3 grams of aniline to obtain 16.4 grams of 1,3-diphenylurea. The yield of the reaction was 77.4%.

Example 2

13.6 grams of benzohydroxamic acid and 32.3 grams of dibromotriphenyl phosphoran were placed in a 500 milliliter three-necked flask containing 200 ml of anhydrous dichloromethane and 20 ml of triethylamine was added slowly with stirring. After stirring for 30 minutes, the solvent was distilled off, and the phenyl isocyanate obtained by distillation under reduced pressure was reacted with 9.3 g of aniline to obtain 16.4 g of 1,3-diphenylurea. The yield of the reaction was 75.5%.

Example 3

7.5 grams of acetohydroxamic acid and 42.2 grams of dibromotriphenyl phospholane were placed in a 500 milliliter three-necked flask containing 200 ml of anhydrous dichloromethane and 20 ml of triethylamine was added slowly with stirring. After stirring for 30 minutes, distillation under reduced pressure was carried out to react acetylisocyanate with 9.3 grams of aniline to obtain 11.7 grams of 1-methyl-3-phenylurea (1-methyl-3-phenylurea). The yield of the reaction was 78.0%.

Example 4

7.5 grams of acetohydroxamic acid and 32.3 grams of dibromotriphenyl phosphoran were added to a 500 ml three-necked round flask containing 200 ml of anhydrous dichloromethane and 20 ml of triethylamine was slowly added with stirring. After stirring for 30 minutes, acetyl isocyanate obtained by distillation under reduced pressure was reacted with 9.3 grams of aniline to obtain 12.0 grams of 1-methyl-3-phenylurea. The reaction yield was 80.0%.

Example 5

7.5 grams of acetohydroxamic acid and 32.3 grams of dibromotriphenyl phosphoran were added to a 500 ml three-necked round flask containing 200 ml of anhydrous dichloromethane and 20 ml of triethylamine was slowly added with stirring. After stirring for 30 minutes, acetyl isocyanate obtained by distillation under reduced pressure was reacted with 5.3 grams of n-propylamine to obtain 9.2 grams of 1-methyl-3-phenylurea. The yield of the reaction was 79.3%.

Example 6

13.6 grams of benzohydroxamic acid and 32.3 grams of dibromotriphenyl phosphoran were placed in a 500 milliliter three-necked flask containing 200 ml of anhydrous dichloromethane and 20 ml of triethylamine was added slowly with stirring. After stirring for 30 minutes, the solvent was distilled off, and the phenyl isocyanate obtained by distillation under reduced pressure was reacted with 5.3 grams of n-propylamine to obtain 13.8 grams of 1-phenyl3-propylurea (1-phenyl-3-propylurea). The yield of the reaction was 77.5%.

Claims (3)

A method for producing organic isocyanate, wherein halophenylphosphoran and hydroxamic acid are reacted at -400 to 150 ° C in the presence of a tertiary amine. The method for producing an organic isocyanate according to claim 1, wherein the halophenylphosphorane is dibromotriphenylphosphoran or dirorotriphenylphosphoran. The compound of claim 1, wherein the tertiary amine is triethylamine, pyridine, quinoline and quinoxaline, hexamethylenetetramine 1, 4-diazabicyclo [2. 2. 2] octane, 1, 5-diazabicyclo [4. 3. 0] non-5-ene, 1,8-diazabicyclo [5. 4. A process for the preparation of organic isocyanates which are undec-7-ene.