GB792163A - Heterocyclic thiocyanates and isothiocyanates, their inter mediates and methods of producing such compounds - Google Patents

Abstract

The invention comprises thiocyanates of the tetrahydrofuran and tetrahydropyran series having the respective formul : <FORM:0792163/IV (b)/1> and the corresponding isothiocyanates. The 2- and 3-bromomethyl derivatives of tetrahydropyran are also novel compounds. The thiocyanates and isothiocyanates are produced by heating a corresponding halomethyl compound, preferably the bromide, with an inorganic thiocyanate such as ammonium thiocyanate in a solvent such as dioxane, a mixture of ethyl alcohol and water or a mixture of ethyl alcohol and dioxane. The 2- and 3-bromomethyl derivatives of tetrahydropyran may be prepared by heating phosphorus tribromide with the corresponding alcohol. The phosphorus tribromide may be prepared in situ by adding bromine to a solution of phosphorus in the alcohol. In examples, (1) tetrahydrofurfuryl bromide is added to a solution of ammonium thiocyanate in alcohol and the mixture is refluxed for 20 hours, then poured into water, extracted with ether, dried, distilled to remove ether and then fractionated to obtain 2-thiocyanomethyl-tetrahydrofuran; (2) 2-hydroxymethyl-tetrahydropyran is reacted with phosphorus tribromide in benzene in the presence of pyridine, the solid formed is filtered off and the product distilled to obtain 2-bromomethyltetrahydropyran; the PBr3 may also be prepared in situ; (3) 3-bromomethyl-tetrahydropyran is prepared as in (2); (4) 2-thiocyanomethyl; and (5) 3-thiocyanomethyl-tetrahydropyran are prepared by a procedure similar to (1). The isothiocyanates may be obtained in the products due to isomerization. The thiocyanates and isothiocyanates can be used as insecticides and as chemical intermediates.