GB1036696A - Alkylated phenothiazines - Google Patents

Abstract

Alkyl substituted phenothiazines of the general formula <FORM:1036696/C4-C5/1> wherein R1 and R2 are either the same and each is an alkyl radical containing from 4 to 12 carbon atoms, or R1 is hydrogen and R2 is an alkyl radical as above defined and in particular wherein either both R's are tertiary octyl or one is tertiary octyl and the other is hydrogen are stated to be valuable constituents in lubricating compositions or other functional fluid compositions, particularly synthetic compositions based on esters.ALSO:Alkyl substituted phenothiazines having the formula <FORM:1036696/C2/1> wherein R1 and R2 are either the same and each is an alkyl radical from 4 to 12 carbon atoms, or R1 is hydrogen and R2 is as above defined, comprising contacting phenothiazine with a 1- or 2-alkene containing in the molecule the same number of carbon atoms as the radical R2, in the presence of as catalyst, sulphuric acid, phosphoric acid, an organic sulphonic acid, a di-alkyl sulphate or a mixture of two or more thereof. It is preferred to use a phenothiazine substantially devoid of free sulphur and of no iodine content as a starting material. Preferred alkenes are iso-pentene, di-isobutylene, propylene dymer or tri-isobutylene. Specific catalysts include methane sulphonic acid, p-toluene sulphonic acid or naphthalene-1: 5-di-sulphonic acid, b -camphor sulphonic acid and di-methyl sulphate. Specially suitable operating temperatures lie between 80 DEG and 150 DEG C. It is also possible instead of employing alkene itself as the reagent to employ the corresponding tertiary alkanol which in the presence of the catalyst dehydrates to the desired alkene. An inert solvent is used for preference in reaction and this may be excess alkene itself.