GB1064116A - Ultra-violet absorbing compositions - Google Patents

Abstract

The invention comprises compounds of the general formula <FORM:1064116/C2/1> wherein W represents hydrogen or a COZ group; Y and Z, which may be the same or different, each represent an OR3 group, where R3 represents hydrogen or an alkyl or alkoxy alkyl group, or an OB group, where B represents a dermatologically acceptable cationic group; and R1 and R2, which may be the same or different, each represent hydrogen or an alkyl or aralkyl group, or together represent a straight or branched chain alkylene group, optionally interrupted by a hetero atom, the values of W, Y, R1 and R2 being chosen so that when <FORM:1064116/C2/2> is a NH2 group in the para position and W is hydrogen, then Y is not an ethoxy or butoxy group, and when R1 and R2 are both methyl and the group <FORM:1064116/C2/3> is in the para position, then W is not hydrogen when Y is a hydroxy, methoxy or ethoxy group and W is not a carbethoxy group when Y is an ethoxy group. The substituted malonates may be made by condensing an appropriate aminobenzaldehyde with an appropriate ester of malonic acid, for example by heating the reactants in solution in a mutual solvent in the presence of at least one condensation catalyst, for example piperidine. The ester may be hydrolysed and converted to the acid or salt. If the desired product contains a primary amino group, the group must be protected, for example, with an acetyl group, which is removed after the condensation. The substituted cinnamates may be made by condensing an aminobenzaldehyde with an ester of acetic acid in a mutual solvent, in the presence of a condensation catalyst, for example sodium metal or sodium hydride. If the acid is required, it may be obtained by hydrolysis of the ester, or alternatively by condensing an aminobenzaldehyde with malonic acid. The salt may be obtained from the acid. A primary amino group must be protected as above.ALSO:An ultra-violet absorbing composition for topical application comprising a dermatologically acceptable liquid or semi-liquid carrier having dissolved or dispersed therein a proportion of at least one compound of the general formula: <FORM:1064116/A5-A6/1> wherein W represents hydrogen or a COZ group; Y and Z, which may be the same or different, each represent an OR3 group, where R3 represents hydrogen or an alkyl or alkoxy-alkyl group, or an OB group, where B represents a dermatologically acceptable cationic group; and R1 and R2, which may be the same or different, each represent hydrogen or an alkyl or aralkyl group, or together represent a straight or branched chain alkylene group, optionally interrupted by a hetero atom, the resultant composition being such as to form on topical application a film or coating on the skin. The sunscreening compositions may take the form of cosmetic oils, alcoholic solutions, lotions, lipstick, ointments, creams and other emulsified products. The compositions may also contain at least one other dermatologically acceptable ultra-violet absorbing compound to enhance the total ultra-violet absorbing properties. Examples of second sunscreening compounds are isobutyl dimethylaminobenzoate, menthyl salicylate and alkoxyalkyl p-methoxycinnamates, preferably having four to six carbons in the alkoxyalkyl group.