| PATENT NUMBER | This data is not available for free |
| PATENT GRANT DATE | June 7, 1983 |
| PATENT TITLE |
4-(1,1-Dimethylethyl)-4'-methoxydibenzoylmethane |
| PATENT ABSTRACT |
The novel 4-(1,1-Dimethylethyl)-4'-methoxydibenzoylmethane is useful as a sunscreen agent. It exhibits outstanding UV-A absorbing qualities in that it brings about a considerable retardation in the ageing of the skin with excellent skin tolerance and stability (light, heat and moisture). 4-(1,1-Dimethylethyl)-4'-methoxydibenzoylmethane furthermore improves the protective action of UV B-filters, i.e. of substances which absorb the erythema-producing UV B-radiation in the range of about 290 to 320 mm. |
| PATENT INVENTORS | This data is not available for free |
| PATENT ASSIGNEE | This data is not available for free |
| PATENT FILE DATE | May 18, 1981 |
| PATENT FOREIGN APPLICATION PRIORITY DATA | This data is not available for free |
| PATENT PARENT CASE TEXT | This data is not available for free |
| PATENT CLAIMS |
I claim: 1. 4-(1,1-Dimethylethyl)-4'-methoxydibenzoylmethane. 2. A light-screen composition comprising an effective ultra violet absorbing amount of 4-(1,1-dimethylethyl)-4'-methoxydibenzoylmethane and at least one other organic material. 3. A light-screen composition according to claim 2 which contains 4-(1,1-dimethylethyl)-4'-methoxydibenzoylmethane in combination with UV B-filter. 4. A light-screen composition according to claim 2 or claim 3, wherein about 1 wt. % to 6 wt. % of 4-(1,1-dimethylethyl)-4'-methoxydibenzoylmethane is present. 5. A sun-screen composition comprising 2 wt. % to 5 wt. % of 4-(1,1-dimethylethyl)-4'-methoxydibenzoylmethane and 2.0 wt. % to 10.0 wt. % of 2-ethylhexyl p-methoxycinnamate. 6. A method for preparing a light screening composition which comprises incorporating 4-(1,1-dimethylethyl-4'-methoxydibenzoylmethane into a cosmetic base. 7. The method of claim 6 wherein the amount of 4-(1,1-dimethylethyl-4'-methoxydibenzoylmethane incorporated is between 1% and 6% by weight of the total composition. 8. The method of claim 6 wherein there is also incorporated a UV B-filter. 9. The method of claim 7 wherein there is also incorporated 1% to 12% by weight of 2-ethylhexyl-p-methoxycinnamate. 10. A topical preparation for application on the skin which comprises an effective amount of 4(1,1-dimethyl)-4'-methoxydibenzoylmethane as a UV-A absorber in a suitable carrier. 11. The preparation of claim 10 wherein the carrier is a suitable cosmetic base. 12. The preparation of claims 10 or 11 wherein the 4-(1,1-dimethylethyl)-4'-methoxydibenzoylmethane is present at a level of 1% by weight to 6% by weight. 13. The preparation of claims 10 or 11 wherein the 4-(1,1-dimethylethyl)-4'-methoxydibenzoylmethane is present at a level of 2% by weight to 5% by weight and wherein there is also present 2-ethylhexyl p-methoxycinnamate at a level of 2% by weight to 10% by weight. 14. A method for protecting the skin from the effects of U.V.-A radiation which comprises applying to the skin an effective amount of 4-(1,1-dimethylethyl)-4'-methoxydibenzoylmethane in a carrier suitable for application on the skin. 15. A method according to claim 14 wherein the carrier is a cosmetic base. 16. The method of claims 14 or 15 wherein the 4-(1,1-dimethylethyl)-4'-methoxydibenzoylmethane is applied as part of a formulation wherein it is present at a concentration of 1% by weight to 6% by weight of the formulation. 17. The method of claims 14 or 15 wherein the 4-(1,1-dimethylethyl)-4'-methoxydibenzoylmethane is applied as part of a formulation wherein it is present at a concentration of 2% by weight to 5% by weight and wherein there is also present 2-ethylhexyl p-methoxycinnamate at a level of 2% by weight to 10% by weight. -------------------------------------------------------------------------------- |
| PATENT DESCRIPTION |
The present invention relates to light-screen agents. It is known that sunlight accelerates the ageing of the skin, this undesirable effect being produced primarily by the UV A-radiation having wavelengths in the range of about 320 to 400 nm which directly tans the skin. It has now been found in accordance with the present invention that 4-(1,1-dimethylethyl)-4'-methoxydibenzoylmethane, namely the compound of the formula ##STR1## is an outstanding UV A-filter in that it brings about a considerable retardation in the ageing of the skin with excellent skin tolerance and stability (light, heat and moisture). It has also been found in accordance with the present invention that the compound of formula I surprisingly improves the protective action of UV B-filters, i.e. of substances which absorb the erythema-producing UV B-radiation in the range of about 290 to 320 nm, although the absorption maximum of the compound of formula I does not lie in this range, but in the range of about 330 to 360 nm. The present invention is based on the foregoing findings and is accordingly concerned in one aspect with light-screen agents containing the compound of formula I hereinbefore, preferably in combination with a UV B-filter. In another aspect, the invention is concerned with the use of the compound of formula I, preferably in combination with UV B-filters, in light-screen agents. When the light-screen agents contain the compound of formula I in combination with a UV B-filter they completely absorb the UV-radiation in the range of 280 to 380 nm (described as a so-called "A+B total block") and protect the skin from premature ageing and in many cases from light dermatoses. The manufacture of the light-screen agents provided by the present invention, especially of skin-protecting preparations for everyday cosmetics, is carried out by incorporating the compound of formula I, preferably in combination with a UV B-filter, in a cosmetic base which is customary for light-screen agents. As UV B-filters in the scope of the present invention, i.e. as substances with absorption maxima between about 290 and 320 nm, there can be named customary UV B-filters such as, for example, the following organic compounds belonging to various classes of substances. (1) p-Aminobenzoic acid derivatives such as, for example, ethyl p-aminobenzoate and other esters such as propyl, butyl and isobutyl p-aminobenzoate, ethyl p-dimethylaminobenzoate, glyceryl p-aminobenzoate and amyl p-dimethylaminobenzoate. (2) Cinnamic acid derivatives such as, for example, 2-ethoxyethyl p-methoxycinnamic acid ester, 2-ethylhexyl p-methoxycinnamic acid ester, p-methoxycinnamic acid ester mixtures and cinnamic acid ester mixtures. (3) Dibenzalazine. (4) Heterocyclic nitrogen-containing compounds such as 2-phenylbenzimidazole derivatives (e.g. 2-phenylbenzimidazole-5-sulphonic acid). (5) Salicylic acid derivatives such as, for example, salicylic acid menthyl ester, salicylic acid homomenthyl ester and salicylic acid phenyl ester. (6) Benzophenone derivatives such as, for example, 4-phenylbenzophenone, 4-phenylbenzophenone-2-carboxylic acid isooctyl ester and 2-hydroxy-4-methoxybenzophenone-5-sulphonic acid. (7) Coumarin derivatives such as, for example, 7-hydroxycoumarin, .beta.-umbelliferoneacetic acid, 6,7-dihydroxycoumarin. (8) Gallic acid derivatives such as, for example, digalloyl-trioleate. (9) Arylidenecycloalkanones such as, for example, benzylidenecamphor, p-tert.butylbenzylidenecamphor (preferred) and methylbenzylidenecamphor. (10) Anthranilic acid derivatives such as, for example, anthranilic acid menthyl ester. (11) Hydroxyphenylbenztriazole. The compounds specified under (2) are preferred, particularly 2-ethylhexyl p-methoxycinnamic acid ester. The cosmetic bases which are conventional for light-screen agents in the scope of the present invention can be any customary preparation which complies with the cosmetic requirements; for example, creams, lotions, emulsions, salves, gels, solutions, sprays, sticks, milks and the like, see also G. A. Nowak, Die Kosmetischen Praparate, 1st Edition 1969, 2nd Edition 1975 (Augsburg). The light-screen action is naturally also dependent on the base used. Furthermore, in the case of the same base the intensity of the light-screen action depends on the concentration of active substance. Suitable concentrations of the compound of formula I in the present light-screen agents lie, for example, between 1 wt. % and 6 wt. %, preferably between 2 wt. % and 5 wt. %. The ratio of the compound of formula I to the UV B-filter is not critical. On economical grounds it amounts, for example, to 1-2 parts of the UV B-filter to 1 part of the compound of formula I. On the basis of its lipophility the compound of formula I can be incorporated well into oil-containing and fat-containing cosmetic preparations, an advantage which is not possessed by, for example, the compounds disclosed in DT-OS 25 40 798 such as dianisoylmethane (A). The compound of formula I is also superior to the light-screen agents disclosed in DT-OS 25 44 180, for example 4-isopropyl-[or 4-(1,1-dimethyl)]dibenzoylmethane (B,C). B and C do have good fat-solubility, but they absorb the UV A-radiation less (.epsilon.=26344 nm or 27396 at 347 nm, compared with 33866 at 355 nm for the compound of formula I. The compound of formula I has optimum properties with respect to adequate fat-solubility and absorption of the UV A-radiation. The compound of formula I is novel and also forms part of the present invention. It can be manufactured according to the known methods of the Claisen condensation of an aromatic ester with a substituted acetophenone (see, for example, R. Hauser et al. in Organic Reactions Vol. VIII, page 59, John Wiley and Sons Inc., New York 1954), namely by reacting a compound of the formula ##STR2## with a compound of the formula ##STR3## wherein in formulae II and III X represents a methoxycarbonyl group and Y represents an acetyl group or X represents an acetyl group and Y represents a methoxycarbonyl group. The reaction of a compound of formula II with a compound of formula III is accordingly conveniently carried out in the presence of a strong base such as, for example, an alkali metal hydride (e.g. sodium hydride), an alkali metal amide (e.g. sodium amide) or an alkali metal alcoholate (e.g. sodium methylate or sodium ethylate). The reaction is conveniently carried out in the presence of an inert solvent such as, for example, an ether (e.g. tetrahydrofuran) or a hydrocarbon (e.g. toluene). The reaction is conveniently carried out at a temperature of about 20.degree.-70.degree. C., especially about 50.degree. C. The isolation of the compound of formula I is preferably carried out by adding ice and an acid (e.g. a mineral acid or an alkanecarboxylic acid such as acetic acid) to the metal salt of the compound of formula I which separates as a solid precipitate, the thus-liberated compound of formula I then being obtained by concentrating the organic phase. If necessary, the compound of formula I can be purified further by recrystallisation from a lower alcohol (e.g. methanol or ethanol). |
| PATENT EXAMPLES | available on request |
| PATENT PHOTOCOPY | available on request |
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