A Reissert compound of bisbenzimidazole can be formed by first reacting benzimidazole with an aliphatic diacid chloride to form bisbenzimidazole and then reacting the bisbenzimidazole with an aliphatic acid chloride and cyanide to form the Reissert compound thereof.

BACKGROUND OF THE INVENTION 
Because of the excellent mechanical and thermal properties imbued to 
polymers of benzimidazole (see Encycl. of Polymer. Sci. and Engineering, 
Second Edition, Vol. 7, pp. 639-665, 1987 and Encycl. of Polymer Sci. and 
Engineering, Second Edition, Vol. 11, pp. 572-601, 1988), it is desirable 
to incorporate this nucleus into these "Reissert compound polymers". 
However, only two examples of a Reissert-type compound from benzimidazole 
have been reported, and they were formed from chloroformates and not from 
acid chlorides (see J. Heterocyclic Chem. 1987, 24, 1349-1351). Attempts 
to use acid chlorides led to destruction of the benzimidazole nucleus (see 
J. Chem. Soc., Chem. Comm., 1984, 1245-1246). Thus, for the production of 
benzimidazole polymers by Reissert chemistry difunctionality was required 
as well as a means of producing Reissert compound moieties from acid 
chlorides. This invention relates to the discovery of methods for 
producing difunctional benzimidazole Reissert compounds. 
DESCRIPTION OF THE INVENTION 
The foregoing problem in regard to undesired bisbenzimidazole formation can 
be overcome by use of a two step process which yields a poly Reissert. The 
first step involves the reaction of benzimidazole to form bisbenzimidazole 
which is then reacted with acid chloride and cyanide to form the Reissert 
compound thereof. 
The first step in the instant process involves reaction of benzimidazole 
with an aliphatic diacid chloride of the general formula ClC(O)RC(O)Cl, 
where R is alkylene (e.g., C.sub.4 -C.sub.6 alkylene) to yield a 
bisbenzimidazole. This reaction can be conveniently performed under the 
following general conditions: Organic solvent (e.g., dimethyl formamide), 
base (e.g., triethylamine), temperatures of about 5.degree. C. to 20 C., 
with mechanical stirring. 
The bisbenzimidazole compound is then reacted with an aliphatic acid 
chloride and cyanide (e.g., trimethylsilyl cyanide) to yield the Reissert 
compound thereof having the structure 
##STR1## 
where A is C(O)RC(O) with R being alkylene. This reaction can be conducted 
in the same type of solvent used in the preceding step, at temperatures 
from 10.degree. C. to 20.degree. C. using amounts of the reagents which 
can range from 1 to 1.2 on a molar ratio basis. 
The following Examples further illustrate the present invention.