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# United States Patent Office 

## PREPARATION OF ORGANIC ISOCYANATES FROM ISOCYANIDE DIHALIDES 

Dieter Arlt, Cologne-Buchheim, Germany, assignor to Farbenfabriken Bayer Aktiengesellschaft, Leverkusen, Germany 

No Drawing. Filed July 3, 1968, Ser. No. 742,172 Claims priority, application Germany, July 6, 1967, P 16 43 975.1 Int. CI. C07c 119/04 U.S. CI. 260-453 P 4 Claims 

Organic isocyanates are produced by reacting organic isocyanide dihalides with anhydrous strong acids contain› ing dissociable hydrogen attached to oxygen. The iso› cyanates produced are useful in the preparation of in› secticides, coatings, adhesives, films, fibers, foams, elas› tomers and the like. 

This invention relates to organic monoisocyanates and polyisocyanates. More particularly, this invention relates to a process for the production of organic monoisocya- nates and polyisocyanates which avoids the use of phos- gene. 

A wide variety of processes are known for the produc› tion of organic isocyanates. The process in most general use, however, is that of phosgenation of primary amines. The use of phosgene, however, is hazardous and phosgene is poisonous. In addition, however, other methods not requiring phosgene are known for the preparation of or› ganic isocyanates including, for example, the Curtius re› arrangement of acid azides as well as the Hofmann and Lossen rearrangements. Moreover, it is •known to thermally decompose carbamates and ureas to form the correspond- ing isocyanate. Still another method of preparing isocya› nate while avoiding the use of phosgene is to react an N,N’-disubstituted or trisubstituted urea with a relatively high boiling isocyanate. The latter process results in the isocyanate separating out and leaving the organic radical of the starting material on the urea. This process, how› ever, suffers from the disadvantage that the ureas are not very soluble in the isocyanates so that large excesses of the isocyanate initially employed are required. It has also been disclosed that isocyanide dichlorides can be reacted with carboxylic acid anhydrides to form isocyanates; Angew. Chemie, 77, 1031 (1965). Unfortunately this reac› tion results only in moderate yields of isocyanates. It is desirable to have a process for the production of iso› cyanates which avoids the use of phosgene because some of the amines have other phosgene sensitive groups in the molecule. Furthermore not all isocyanates are ob› tainable by the phosgenation of amines. It is also desir- able to have a process for the production of isocyanates yielding relatively high yields of isocyanates in addition to avoiding the use of phosgene. 

It is, therefore, an object of this invention to provide a process for the preparation of organic isocyanates which avoids the use of phosgene. A further object of this in› vention is to provide a process for the preparation of iso› cyanates having improved yields. A further additional ob› ject of this invention is to provide a process for the preparation of organic isocyanates from organic isocyanide dihalides. A still further object of this invention is to provide a process for the preparation of organic isocya› nates from organic isocyanide dihalides having high yields of isocyanates. Another still further additional object of this invention is to provide a process for the production of organic isocyanates which find use in the field of plas› tics and resins. 

## ABSTRACT OF THE DISCLOSURE 

## 1 

3,639,442 

The foregoing objects and others which will become apparent from the following description are accomplished in accordance with the invention, generally speaking, by providing a process for the production of organic isocya- nates wherein an organic isocyanide dihalide is reacted with an anhydrous strong acid containing dissociable hy› drogen attached to oxygen. More particularly, the objects of this invention are accomplished by preparing organic isocyanates by reacting isocyanide dihalides with anhy› drous strong acid containing dissociable hydrogen at› tached to oxygen and heating the reaction product. 

The novel, chemically unique process of this invention comprises reacting an organic isocyanide with an anhy› drous strong acid in which the hydrogen atom or atoms are attached to oxygen, the reaction proceeding in accord› ance with the following reaction sequence: 

<img src='content_image/926142.jpg'>

wherein R is an m-valent organic radical, Hal is a halogen atom, Y is the radical of a strong acid and m is a whole number of at least 1. Although the intermediate reaction product shown in brackets may be separated and collected, if desired, this is generally not done since the organic isocyanate is generally the most desired end product. In the process of this invention the strong acid is converted into an acid halide which, if desired, may be converted back into the acid by reaction with water. 

The process of this invention is suitable for the proJ duction of any organic mono- or polyisocyanate of the formula 

from isocyanide dihalides of the formula 

wherein R is an m-valent organic radical, Hal is a halogen atom and m is an integer of at least 1, preferably 1 or 2. In the formulae, R may be any suitable organic radical such as, for example, a substituted or unsubstituted, satu› rated or unsaturated organic radical selected from the group consisting of an aliphatic, cycloaliphatic, araliphatic, aromatic or heterocyclic radical which may be substituted with any suitable substituent which is non-reactive with an isocyanato group or with the strong acid reactant such as, for example, halo-, nitro- and the like. Preferably R is an m-valent substituted or unsubstituted aliphatic radical such as alkyl, alkenyl, alkynyl, cycloalkyl-alkyl, cyclo› alkenyl-alkyl, aralkyl, aralkenyl, aralkynyl and the like; a cycloaliphatic radical such as cycloalkyl, cycloalkenyl, alkylcycloalkyl, alkylcycloalkenyl, arylcycloalkyl, arylcy› cloalkenyl and the like; an aromatic radical such as aryl, alkaryl, alkenylaryl, alkynylaryl; cycloalkyl-aryl, cyclo› alkenyl-aryl and the like; a heterocyclic radical or a hydro› carbon substituted heterocyclic radical. Most preferably, however, R is an m-valent organic radical selected from the group consisting of alkyl or alkenyl having from 1 to 15 carbon atoms, cycloalkyl having up to 12 carbon atoms, preferably 5 or 6 carbon atoms, benzyl, phenyl, naphthyl, toluyl, diphenyl alkane having from 1 to 4 car› bon atoms in the alkane moiety and the chloro-, bromo-, fluoro or nitro substituted derivatives thereof. Although m. may be any suitable whole number of at least 1 such as, for example, 1, 2, 3, 4 and the like, m is preferably 

<img src='content_image/926144.jpg'>

Patented F eh. 1, 1972 

## 2 

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# 3,639,442 

