GB804016A - Insulating and cooling oils and heat transfer media - Google Patents

Abstract

Compositions suitable as heat transfer media, insulating and cooling oils comprise a mixture of chlorinated diphenyls containing 0-8 per cent of p:p1-dichlorodiphenyl and 32-42 per cent by weight of chlorine. Such mixtures may be produced by chlorinating diphenyl by methods in which little or no p:p1-dichlorodiphenyl is formed (e.g. by means of sulphuryl chloride, preferably in the presence of aluminium chloride, or by means of chlorine in the presence of about 0.5-20 per cent of pyrolusite), or by using the conventional halogen carriers (e.g. iron or antimony chloride) for the chlorination and then supercooling the product until the undesired p:p1-dichlorodiphenyl crystallizes out, and separating the crystals by filtration or centrifuging. In examples: (1) sulphuryl chloride is run into a melt of diphenyl, aluminium chloride is gradually added, and the resulting mixture is neutralized and distilled, giving a product containing 40 per cent of chlorine; (2) chlorine is introduced into a mixture of molten diphenyl and pyrolusite, and the product, containing 35 per cent of chlorine, is separated by filtration from the pyrolusite or the manganese chloride formed therefrom, neutralized and distilled; (3) diphenyl is chlorinated to 38 per cent chlorine content in the presence of antimony chloride at 100-150 DEG C., and p:p1-dichlorodiphenyl is crystallized from the product, and filtered off before or after neutralization. Specification 493,961, [Group XIII], is referred to.