United States Patent Office  3,639,442  Patented F eh. 1, 1972  1  2  3,639,442  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.  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  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:  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  ABSTRACT OF THE DISCLOSURE  (  /Hal)  -m(H-Hal)  R -N=C’\._  + mYOH  Hal  m  [ R(-N=C~::t] --> R(-N=C=O)m + mY-Hal  R (N=C=O  /  /Hal)  R-\N=C’-...  Hal m 