Patent GB-657580-A (GB)
Title: Improvements in insecticides
IPC: A01N41/02
Filed: 1948-12-29
Abstract: Di-esters of sulphurous acid useful as insecticides (see Group VI) and wherein one of the esterifying groups is an alkyl radical containing 7 to 16 carbon atoms and the other esterifying group is a chloroalkyl radical containing 2 to 4 carbon atoms and 1 to 3 chlorine atoms and having no chlorine atom attached to the alpha carbon atom, are obtained by reacting either a chloroalkanol or an alkanol with thionyl chloride, and reacting the thus-formed chloroalkylchlorosulphinate or alkyl chlorosulphinate with an alkanol or a chloroalkananol, respectively, the chloroalkanol in both steps of the process containing 2 to 4 carbon atoms and 1 to 3 chlorine atoms and having no chlorine atom attached to the alpha carbon atom and the alkanol in both steps of the process containing 7 to 16 carbon atoms.  It is desirable that the alpha carbon atom of the chloroalkyl radical be attached to at least one hydrogen atom.  The reaction of the chloroalkylchlorosulphinate with the alkanol may be carried out in the presence of a proton acceptor such as pyridine, dimethylaniline or trimethylamine to sequester the hydrogen chloride, and in a solvent such as benzene, xylene or solvent naphtha.  The sequestering agent may be omitted if the reaction is carried out under reduced pressure or in the presence of a dry inert gas such as air or nitrogen.  A long list of di-ester products is given, the di-esters being derived from 2-chlorethanol, 3-chloropropanol, 1-methyl-2-chloroethanol, 2-chloropropanol, 2(3- or 4-)-chlorobutanol, 3-chloroisobutanol, 1-chloromethylpropanol and 1-methyl-2-chloropropanol.  Other diester products of the invention are those derived from chloroalkanols having 2 and 3 chlorine atoms, e.g. 2,2-dichloroethanol; 2,2,2-trichlorethanol, 2,3-(or 2,2-)-dichloropropanol, 1 - chloromethyl - 2 - chloroethanol; 3,3 - dichloropropanol; 3,3,3-trichloropropanol; 2,3-(or 2,4-)-dichlorobutanol; 3,4-dichlorobutanol and 1,1 - di - methyl - 2,2,2 - trichloroethanol.  Examples describe the production of 2-chloroethyl lauryl sulphite, 2-chloroethyl n-decyl sulphite, 3-chloropropyl lauryl sulphite, 4-chlorobutyl n-decyl sulphite, 1-methyl-2-chloroethyl n-decyl sulphite, 1-chloromethyl-2-chloroethyl n-heptyl sulphite, 2,3-dichloropropyl decyl sulphite and 2,2,2-trichloroethyl n-octyl sulphite.  In each case the appropriate chloroalkanol is reacted with thionyl chloride and the chloroalkylchlorosulphinate is then reacted with the appropriate alkanol in the presence of pyridine. In the production of 4-chlorobutyl n-decyl sulphite some di-4-chlorobutyl sulphite is stated to be obtained in addition to 4-chlorobutyl chlorosulphinate in the first step of the process. In a further example 1,1-dimethyl-2,2,2-trichloroethyl n-decyl sulphite is obtained by adding thionyl chloride to decyl alcohol to form decylchlorosulphinate and the latter is then reacted with 1,1-dimethyl-2,2,2-trichloroethyl alcohol in the presence of pyridine and benzene.  The di-ester products may be applied in undiluted form to loci to be protected against insects or may be admixed with a carrier (see Group VI).ALSO:An insecticidal composition comprises di-esters of sulphurous acid wherein one of the esterifying groups is an alkyl radical containing 7 to 16 carbon atoms and the other esterifying group is a chloroalkyl radical containing 2 to 4 carbon atoms and 1 to 3 chlorine atoms and having no chlorine atom attached to the alpha carbon atom (see Group IV(b)) admixed with a carrier therefor. The said di-esters may be applied to loci to be protected against insets as dusts admixed with or absorbed on powdered solid carriers, e.g. mineral silicates such as mica, talc, pyrophyllite and clays or as liquids or sprays when in a liquid carrier, e.g. in a solvent or dispersed in a non-solvent medium such as water. The esters may also be admixed with powdered solid carriers such as mineral silicates together with small amounts of a dispersing agent and this mixture may be applied as a suspension in water. The products may also be applied by the aerosol method and the solution may be prepared by dissolving the di-ester product in the aerosol carrier which is liquid under pressure but which is gas at ordinary temperature and pressure, or the aerosol solution may be prepared by first dissolving the chemical in a less volatile solvent and then admixing such solution with the highly volatile liquid aerosol carrier.  The products may also be admixed with other insecticides, fungicides or bactericides.  Examples are given to show the effectiveness of the products for controlling the greenhouse red spider mite and pea aphid, the products being applied as aqueous emulsions prepared with small amounts of a commercial emulsifying agent comprising the reaction product of castor oil and ethylene oxide and in some cases with a wetting agent comprising dodecyl benzene sodium sulphonate present. Tabulated results are given showing the results obtained with several di-esters in which one of the esterifying groups is a chloroalkyl radical such as 2-chloroethyl; 3-chloropropyl; 4-chlorobutyl; 1-methyl-2-chloroethyl; 1-chloromethyl-2-chloroethyl; 2, 3 dichloropropyl, 2, 2, 2-trichloroethyl and 1, 1 dimethyl-2, 2, 2-trichloroethyl and the other esterifying group is an alkyl radical of 7 to 16 carbon atoms. Comparative results are also given when other di-esters of sulphurous acid such as ethyl lauryl sulphite, dilauryl sulphite, di (2-chloroethyl) sulphite, 2-chloroethyl ethyl sulphite and 2-chloroethyl n-butyl sulphite are used.