GB637252A - Process for preparing halogen-containing unsaturated aliphatic nitro-compounds - Google Patents

Abstract

Halogen-containing unsaturated aliphatic nitro-compounds are prepared by reacting olefinic halogen compounds, having the general formula <FORM:0637252/IV (b)/1> where R1, R2, R3 and R4 are hydrogen or alkyl groups, to react with aqueous nitrous acid or with nitrous gases, i.e. gases comprising nitrogen trioxide (N2O3) or mixtures of other nitrogen oxides, such as NO and NO2 which under the conditions employed react to yield nitrogen trioxide. Generally, the olefinic halogen compound is treated with a dilute solution of mineral acid and an alkali nitrite, suitable acids being sulphuric, nitric or phosphoric acid; hydrogen halides are less suitable owing to possible formation of additive compounds with these acids. Alternatively, the process may be effected by reacting the nitrous gases with the olefinic halogen compound dissolved in an organic solvent such as benzene. Reaction is normally carried out at room temperature but higher or lower temperatures may be used; continuous or batch-wise procedure may be followed at normal, raised or reduced pressures. The main products contain a primary nitro-group and are stated to be new; additive compounds with nitrous anhydride which are probably formed as intermediates may be present and may be decomposed by heat, preferably by mixing the crude product with an inert organic solvent or dispersing agent and heating at 80-110 DEG C. In the example, an aqueous solution of sodium nitrite is slowly added to a stirred mixture of methallyl chloride and 20 per cent aqueous sulphuric acid, the resulting oil layer removed, water-washed and heated with toluene to decompose additive compounds and then distilled first to remove solvent and then the desired 2-chloromethyl-3-nitro propene-1. The latter is purified by dissolving in alkaline lye, extracting with ether, acidifying the purified alkaline solution and then again extracting with ether. Methallyl bromide, 3-chloro-2-methyl butene - 1, 3 - chloro - 2 : 3 - dimethyl butene - 1 and 3 - chloro - 2 - methyl pentene-1 are other specified starting materials. The products may be used to combat insects and other noxious organisms.