SULFONATE SALTS OF SUBSTITUTED BENZIMIDAZOLES
Oct., 1947
2-Imino-3,3 -diphenyl -5-methyltetrahydrofuran (XII) was obt,ained from the reaction of propylene oxide and cliphenylacetonitrile. A procedure .for the preparation of diphenylace-
[CONTRIBUTION FROM
THE
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tonitrile through the bromination of benzyl cyanide followed by reaction with benzene and aluminum chloride is described. GLENOLDEN, PENNSYLVANIA
RECEIVED MAY15, 1947
NOYESCHEMICAL LABORATORY, UNIVERSITY OF ILLIXOIS]
Sulfonate Salts of Substituted Benzimidazoles1 BY NELSONJ. LEONARD, DAVIDIT. CURT IN^
AND
KARLM. BECK
A generally satisfactory method for the preparation of “sulfa” drugs,3when applied to the syrithesis of 2-sulfabenzimidazole, led to the formation of a product for which Price and Reitsema4have suggested a salt structure. 2-Aminobenzimidazole sulfanilate (I) has now been prepared by direct combination of 2-aminobenzimidazole and sulfanilic acid. This salt corresponds in physical properties to the “sulfabenzimidazole” of Raiziss, Clemence and Reifelder.
solution.6 Many other arylsulfonic acids havc been used to identify amines and likewise have been identified by amines through salt formation. Occasionally amine arylsulfonates have been obtained in reactions from which one might be led to expect other products. Rouiller’ obtained benzamidine benzenesulfonate when benzoic acid and benzenesulfonamide were heated a t 225’. Clarke and Gillespies obtained guanidine benzenesulfonate from guanidine carbonate and benzenesulfonyl chloride in aqueous potassium carbonate. so,Karrer and EpprechtQshowed that guanidine pnitrobenzenesulfonate was the product oi the reaction of guanidine nitrate with p-nitrobenzenesulfonyl chloride in aqueous sodium hydroxide by its identity with the salt obtained directly from p-nitrobenzenesulfonic acid and guanidine carI X = P-?XH2 bonate. Guanidine m-nitrobenzenesulfonate was I1 X = WL-NO~ 111 X = W L - N H ~ obtained by the same r n e t h ~ d . ~ In the present investigation, 2-aminobenzimida2-Aminobenzimidazole m-nitrobenzenesulfonate (11) and 2-aminobenzimidazole metanilate (111) zole sulfanilate (I), m-nitrobenzenesulfonate (11), have also been prepared by direct salt formation and metanilate (111) have been prepared by comand have been shown to be identical with these bination of 2-aminobenzimidazole with the corsulfonate salts as obtained by Price and , R e h e m a responding arylsulfonic acid in aqueous solution. by indirect met’hods. 2-Amino-5-chlorobenzimid- The study initiated by Price and Reitsema on the azole m-nitrobenzenesulfonate has been formed condensation products of arylsulfonyl chlorides by combination of m-nitrobenzenesulfonic acid with 2-aminobenzimidazole in pyridine has been with 2-amino-5-chlorobenzimidazole(V) . Com- extended to chloro-substituted 2-aminobenzimidapound V has been shown to be the monochlorina- zole in order to determine the effect of rendering the tion product of 2-aminobenzimidazole and the ring-nitrogen less basic. The reaction of 9-chlorocondensation product of p-chloro-o-phenylenedi- o-phenylenediamine (IV) with cyanogen bromide produced a compound which had the correct anamine with cyanogen bromide. Salts of aromatic amines with m-nitrobenzene- alysis for 2-amino-5-chlorobenzimidazole(V) and sulfonic acid were first made by Keyworth5 for use also for the substituted cyanamide in which the as derivatives for the identification of certain BrChi amines. The salts were prepared by ,treating c10;: sodium or potassium m-nitrobenzenesulfonate with the arylamine hydrochloride in aqueous soluIV tion. The contrasting use of an organic base to isolate and identify arylsulfonic acids is illustrated by the reaction of S-benzylthiouronium chloride with sodium m-nitrobenzenesulfonate in aqueous
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(1) Presented before the Division of Organic Chemistry a t the 111th meeting of the American Chemical Society, Atlantic City, S e w Jersey, April I O , 1947, ( 2 ) Present atldri,,-n. 1)rpartmerit uf
