GB690972A - Thiosemicarbazones - Google Patents

Abstract

The invention comprises lower 3- or 4-alkoxybenzalthiosemicarbazides having an unsaturated linkage in the alkyl radical, and a process for making them which comprises reacting lower 3- or 4-alkoxybenzaldehydes or their functional derivatives containing an unsaturated linkage in the alkyl radical, with thiosemicarbazide. In examples: (1) 4-allyloxybenzaldehyde and thiosemicarbazide are refluxed with ethanol and a few drops of acetic acid to yield 4-allyloxybenzalthiosemicarbazide; (2) 3-allyl-4-allyloxybenzalthiosemicarbazide is similarly prepared from 3-allyl-4-allyl-oxybenzaldehyde; (3) 4-crotyloxybenzaldehyde (obtainable by heating 4-hydroxybenzaldehyde, crotyl bromide and potassium carbonate in ethanol) is similarly converted to 4-crotyl-oxybenzalthiosemicarbazide; (4) 3-allyloxybenzalthiosemicarbazide is made from 3-allyl-oxybenzaldehyde (obtainable from 3-hydroxybenzaldehyde, allyl bromide and potassium carbonate); (5) 3-crotyloxybenzalthiosemicarbazide is made from 3-crotyloxybenzaldehyde (obtainable from 3-hydroxybenzaldehyde, crotyl bromide and potassium carbonate); (6) the compound <FORM:0690972/IV (b)/1> (obtainable by heating 1,4-dibromobutene with 4-hydroxybenzaldehyde and potassium hydroxide in ethanol) is converted to the dithiosemicarbazone; and (7) 4-propargyloxybenzalthiosemicarbazide is obtained from 4-propargyloxybenzaldehyde (obtainable by heating propargyl bromide with 4 - hydroxybenzaldehyde and potassium hydroxide in ethanol). The compound p - chloroallyloxybenzalthiosemicarbazide also is referred to.