The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 30, 1991
Filed:
Dec. 07, 1989
Duphar International Research B.V., Weesp, NL;
Abstract
The invention relates to a method for the photochemical conversion of tachysterol compounds into previtamin D compounds and of trans-vitamin D compounds into cis-vitamin D compounds under the influence of radiation, by exposing the tachysterol compound and trans-vitamin D compound, respectively, dissolved in a suitable solvent system, in the presence of a polymeric photosensitizer consisting of a polymer chain ('backbone') comprising covalently bound sensitizers suitable for the photochemical conversion, to light with a wavelength of preferably between approx. 300 and approx. 1,000 nm, and by then isolating the resulting previtamin D compound and cis-vitamin D compound, respectively, in which a polymeric photosensitizer is used, the polymer chain of which has been selected from the group consisting of a polyether chain, an amino groups-containing polymer chain and a block copolymer chain comprising polyether segments and/or amino groups-containing polymer segments, in such a manner that the polymeric photosensitizer dissolves in the solvent system during the exposure to radiation but either upon cooling precipitates from the solution and can be separated, or, in case said polymer chain comprises amino groups, can be protonated with a suitable acid substance and be removed in an after-treatment. The invention also relates to a polymeric photosensitizer to be used for the said method.