Patent GB-655432-A (GB)
Title: A process for the production of 1.3-dihalopropylenes
IPC: C07C17/00
Filed: 1947-12-12
Abstract: 1,3-Dihalopropylenes, stated to be agents for fumigating and disinfecting soils (see Group VI), especially 1,3-dichloropropylene or mixtures containing said compounds and other polyhalogenated hydrocarbons having three carbon atoms in the molecule are obtained by subjecting a 1,2-dihalopropane, especially 1,2-dichloropropane, with free halogen, especially chlorine, to elevated temperatures between 300 DEG  and 800 DEG  C., preferably between 400 DEG  and 600 DEG  C., the molecular ratio of dihalopropane to halogen being in excess of 1 : 1 but not greater than 3 : 1.  One or more of the reactants may be heated before mixing, thus 1,2-dichloropropane may be preheated to 300 DEG  to 350 DEG  C.  The heating of the reactants may be effected by introducing heated inert gases, e.g. nitrogen or steam.  The reaction may be accelerated by the use of light and/or carbon, antimony halides or stannic halides as catalysts.  The reaction may be effected in the liquid phase but is preferably effected in the vapour phase and the halogen may be added in stages. In an example, 1,2-dichloropropane (1.27 mols.) is preheated to 320 DEG  C. and mixed with chlorine (1 mol.).  The mixture is passed through a zone maintained at 500 DEG  C., and the reaction products are washed with water to remove the hydrogen chloride formed.  The organic chlorides produced include allyl chloride, beta-chloropropylene and alpha-chloropropylene, saturated and unsaturated dichlorides, unsaturated trichlorides (mainly 1,3,3 - trichloropropene - 1). The unsaturated dichlorides consist mainly of 1,3-dichloro propene-1, the remainder being 2,3-and 3,3-dichloropropene-1.  In a similar manner a polybrominated fraction containing 1,3-dibromopropene-1 is obtained from 1,2-dibromopropane and bromine.  Instead of using a halogen identical with that of the dihalopropane employed it is possible to use a different halogen thus a 1,3-dihalopropene-1 in which one of the halogens is chlorine and the other is bromine may be obtained from 1,2-dibromopropane and chlorine.  Specification 508,417 is referred to.  According to the Specification as open to inspection under Sect. 91 the reaction may be effected with the halogen in excess or with the reactants in equimolecular amounts and the molecular ratio of 1,2 dihalopropane to the corresponding halogen may be higher than 3 : 1.  This subject-matter does not appear in the Specification as accepted.ALSO:1, 3-Dihalopropylenes, obtained by reacting a 1, 2-dihalopropane with free halogen (see Group IV(b)), as well as mixtures thereof with other polyhalogenated hydrocarbons, preferably those containing from three to six carbon atoms per molecule are stated to be effective soil fumigants.  In the production of 1, 3-dichloropropene-1 from 1, 2-dichloropropane and chlorine, the reaction product is distilled to separate the monochlorinated hydrocarbons and the remaining fraction containing the unconverted 1, 2 dichloropropane, the unsaturated dichloropropylenes and trichloro compounds with or without the higher boiling compounds may be employed as a soil fumigant either as such or in combination with other organic compounds such as hydrocarbons.