Patent GB-478525-A (GB)
Title: Process for the preparation of diphenylguanidine
IPC: C07C277/08
Filed: 1936-08-14
Abstract: Diphenylguanidine hydrochloride is produced by the action of a slight excess of anhydrous cyanogen chloride, prepared as described below, on anhydrous aniline, preferably in counterflow. The cyanogen chloride is prepared by passing the stoichiometric amount of chlorine into aqueous sodium cyanide solution at below 15,5 DEG  C., then adding sufficient caustic alkali to establish a faintly alkaline reaction, heating the liquid or passing steam therethrough to cause evolution of cyanogen chloride, and passing the latter over calcium chloride or like dehydrating agent, if desired after cooling.  As shown, cyanogen chloride is generated in a number of vessels, 1 each provided with heating or cooling jackets and coils 2, 5, a chlorine supply pipe 9, a cyanide solution supply pipe 12, and an outlet pipe 15 for the cyanogen chloride.  Pipes (not shown) for admitting caustic alkali solution are also provided.  The cyanogen chloride passes by a pipe 17 to a <PICT:0478525/IV/1> cooling coil 18 and a drying tower 21, and thence in turn through a series of reaction vessels 25, 25<1>, 25<11>, through which anhydrous aniline, supplied by a pipe 30, flows in the opposite direction.  Fused diphenylguanidine hydrochloride collects in a vessel 34, and is withdrawn through a pipe 35 and converted into diphenylguanidine in known manner.  The slight excess of cyanogen chloride is withdrawn through a pipe 29, which is preferably connected to a source of reduced pressure.  The cyanogen chloride generators are preferably operated alternately, and may be connected to a gas holder.  British Specification 255,220, [Class 2 (iii)], and U.S.A. Specifications 1,884,509 and 1,897,220 are referred to.  The Specification as open to inspection under Sect. 91 refers generally to the manufacture of guanidine derivatives by treating an anhydrous amine in counterflow with an anhydrous gaseous cyanogen halide.  It states that the amine may be dissolved or dispersed in an anhydrous medium, and mentions methylamine and toluidine as amines which may be treated.  This subject-matter does not appear in the Specification as accepted.ALSO:<PICT:0478525/III/1> Cyanogen chloride is prepared by passing the stoichiometric amount of chlorine into aqueous sodium cyanide solution at below 15,5 DEG  C., then adding sufficient caustic alkali to establish a faintly alkaline reaction, heating the liquid or passing steam therethrough to cause evolution of cyanogen chloride, and passing the latter over calcium chloride or like dehydrating agent, if desired, after cooling.  Apparatus is described comprising a number of vessels 1 each provided with heating or cooling jackets and coils 2, 5, a chlorine supply pipe 9, a cyanide solution supply pipe 12, and an outlet pipe 15 for the cyanogen chloride. Pipes (not shown) for admitting caustic alkali solution are also provided.  The cyanogen chloride passes by a pipe 17 to a cooling coil 18 and a drying tower 21, and thence in turn through a series of reaction vessels 25, 25<1>, 25<11> in which it is utilized for the manufacture of diphenyl-guanidine.