GB802655A - Process for the production of aromatic disulphonyl hydrazides and their use as gas producing compositions - Google Patents

Abstract

Naphthalene-1 : 5-disulphonyl hydrazide, prepared by reacting naphthalene-1 : 5-disulphonyl chloride with hydrazine (see Group IV (b)), is used as a blowing agent in synthetic rubber and resinous plastic compositions to produce closedcell sponges. In examples: (1) a mixture of butadiene-styrene copolymers, hydrated calcium silicate, soft clay, benzothiazyl disulphide, di-orthotolylguanidine, sulphur, stearic acid, zinc oxide and naphthalene-1 : 5-disulphonyl hydrazide are mixed and cured in a mould to produce a sponge composition; (2) a chloroprene polymer containing thiuram compounds, stearic acid, benzothiazyl disulphide, silica and naphthalene - 1 : 5 - disulphonyl hydrazide are mixed and cured as in (1); (3) polyvinyl chloride, dioctyl phthalate, barium cadmium laurate and naphthalene - 1 : 5 - disulphonyl hydrazide are mixed and cured as in (1).ALSO:Aromatic disulphonyl hydrazides are prepared by mixing an aromatic disulphonyl chloride with a dilute aqueous solution of hydrazine, allowing the mixture to react at a temperature below the decomposition temperature of the required disulphonyl hydrazide, adding a strong base (as defined below) to the mixture to neutralize the hydrochloric acid formed during the reaction, and separating the resultant aromatic disulphonyl hydrazide, the reaction being allowed to continue until substantially all the free hydrazine has reacted before the strong base is added, the strong base freeing the hydrazine from the hydrazine hydrochloride formed during the reaction for further reaction with unreacted aromatic disullhonyl chloride and being added slowly so that a yield of at least 90 per cent is obtained. The "strong base" is defined as an alkali or alkaline earth metal hydroxide. The preferred product is naphthalene - 1 : 5 - disulphonyl hydrazide which is used as a blowing agent in natural and synthetic rubbers and in resinous plastics (see Groups IV (a) and V). It is preferably made from naphthalene-1 : 5-disulphonyl chloride obtained by the process described in Specification 802,654. In an example, naphthalene-1 : 5-disulphonyl chloride is slowly added to an aqueous solution of hydrazine and sodium hydroxide solution is added slowly after one hour, the mixture being stirred for three hours and the naphthalene-1 : 5-disulphonyl hydrazide obtained by filtration.ALSO:Naphthalene-1 : 5-disulphonyl hydrazide, prepared by reacting naphthalene-1 : 5-disulphonyl chloride with hedrazine (see Group IV(b)), is used as a blowing agent in rubber and resinous compositions to produce closed-cell sponges.