Abstract: A process for the preparation of optically pure D- or L-lactic acid by fermentation of an aqueous nutrient medium, which contains nitrogen, vitamins, aminoacids, sugars and trace elements, by means of a microorganism, at pH 4-6, wherein the nutrient medium contains brewers' yeast as the source of nitrogen, vitamins, aminoacids and trace elements.

Abstract: A process for the preparation of D-carbamyl-.alpha.-aminoacids of the formula ##STR1## where R has the meanings given in the description, by enzymatic cleavage of the corresponding hydantoins by means of thermophilic, non-sporulating hydantoin-cleaving micro-organisms or of extracts therefrom.

Abstract: Monoacetals of aromatic 1,2-diketones are manufactured by reacting the corresponding 1,2-diketones, in an organic solvent, with an acid ester (R.sup.1).sub.n X as alkylating agent and an alcoholate (R.sup.2 O).sub.m Me, where R.sup.1 and R.sup.2 are identical or different hydrocarbon radicals of 1 to 12 carbon atoms, which may or may not be substituted, n and m are integers from 1 to 3, X is a monobasic, dibasic or tribasic acid radical and Me is a metal of main groups 1 to 3 of the periodic table of the elements. The resulting diketone monoacetals are particularly suitable for use as photoinitiators in photopolymerizable compositions.

Abstract: Quaternary ammonium compounds of the formula ##STR1## where R.sup.1 and R.sup.2 are identical or different and each is H, halogen, phenyl, alkyl, alkoxy or alkylthio,R.sup.3 is H or alkyl, hydroxyalkyl, cycloalkyl or aralkyl,R.sup.4 and R.sup.5 are identical or different and each is alkyl, phenyl, cycloalkyl or aralkyl orR.sup.4 and R.sup.5 together are a --(CH.sub.2).sub.4 -- bridge, a --(CH.sub.2).sub.5 -- bridge or a --(CH.sub.2).sub.2 --O--(CH.sub.2).sub.2 -- bridge,R.sup.6 is alkyl andX.sup..crclbar. is Cl.sup..crclbar., Br.sup..crclbar., I.sup..crclbar., CH.sub.3 SO.sub.4.sup..crclbar. or C.sub.2 H.sub.5 SO.sub.4.sup..crclbar., a process for their preparation from Mannich bases of the formula ##STR2## and alkylating agents, and the use of these quaternary ammonium compounds as initiators for the photopolymerization of polymerizable mixtures containing olefinically unsaturated compounds, especially for the preparation of aqueous polymer dispersions or polymer solutions.

Abstract: A photopolymerizable composition for the manufacture of printing plates and relief plates, based on a mixture, containing a photoinitiator, of photopolymerizable olefinically unsaturated monomers and a polymeric binder, contains up to 0.1% by weight of an etherified thioanthraquinone for improving the relief image in the production of relief plates.The composition advantageously also contains a small amount of an organic tertiary amine or of an aromatic .alpha.-ketocarboxylic acid or its ester and/or of an inhibitor, e.g. the salt of an organic N-nitrosohydroxylamine.

Abstract: Photopolymerizable binders for printing inks, coatings and printing plates, based on olefinically unsaturated compounds, with or without a polymeric binder component, and containing a diaminobenzophenone compound as the photosensitizer, are improved in respect of their toxicity and shelf life if the diaminobenzophenone compound has the formula R.sup.1 R.sup.2 N--C.sub.6 H.sub.4 --CO--C.sub.6 H.sub.4 --NR.sup.3 R.sup.4, where R.sup.1 and R.sup.3 are H(OR.sup.5).sub.x radicals, R.sup.5 being alkylene of 2 or 3 carbon atoms and x being 1, 2 or 3, and R.sup.2 and R.sup.4 are each alkyl of 1 to 4 carbon atoms or are radicals of the type of R.sup.1 and R.sup.3.

Abstract: Unsymmetrical monoketals of aromatic 1,2-diketones ##STR1## wherein R.sup.1 and R.sup.2 are different radicals, are manufactured by reacting the corresponding aromatic 1,2-diketones, in an organic solvent, with an acid ester (R.sup.1).sub.n X as alkylating agent and an alcoholate (R.sup.2 O).sub.m Me, where n and m are integers from 1 to 3, X is an acid radical and Me is a metal of main groups 1 to 3 of the periodic table of the elements. The resulting diketone monoacetals are particularly suitable for use as photoinitiators in photopolymerizable compositions.

Abstract: A photopolymerizable composition which contains one or more olefinically unsaturated compounds and from 0.2 to 20% by weight (based on the unsaturated compound(s)) of a photoinitiator, with or without conventional additives, the photoinitiator being a mixture of one or more aromatic carbonyl compounds of the general formula (A) ##STR1## where Ar is an ortho-arylene radical which may or may not be substituted by one or more radicals R.sup.1 to R.sup.4, R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are identical or different and each is H, alkyl or 1 to 5 carbon atoms, phenyl, halogen, alkoxy of 1 to 5 carbon atoms, alkaryl of 7 to 11 carbon atoms, aralkyl of 7 to 11 carbon atoms or --CO.sub.2 R.sup.9, where R.sup.9 is alkyl of 1 to 5 carbon atoms, and n is 0 or 1, and an amine, with or without an aromatic carbonyl compound which differs from (A).This photopolymerizable composition is particularly suitable for the manufacture of photopolymer printing plates and UV-curing printing inks.

Abstract: Photopolymerizable coating compositions contain, as the binder, olefinically unsaturated compounds having a boiling point above 50.degree. C, together with from 0.5 to 15% by weight of photoinitiators, based on the binder. The photoinitiators are a mixture of an aromatic carbonyl compound A, which is a derivative of benzoin or benzil, which has at least one carbon-oxygen single bond in the .alpha.-position relative to the carbonyl group, an aromatic carbonyl compound B which is derived from benzophenone, fluorenone, anthraquinone, xanthene, thioxanthone or acridone, and an amine C of the general formula ##STR1## where R', R" and R"' are H, alkyl of 1 to 10 carbon atoms, cycloalkyl of 3 to 10 carbon atoms, aryl, hydroxyalkyl of 1 to 8 carbon atoms or alkoxyalkyl of 2 to 4 carbon atoms, but at most 2 substituents are H and at most 2 substituents are aromatic.These coating compositions may be used for finishing various substrates, as fillers or as printing inks.

Abstract: A photopolymerizable composition containing olefinically unsaturated compounds, optional conventional additives and, as photoinitiator, a mixture of a thioether of the general formula (I): ##STR1## where R.sup.4 is phenyl, naphthyl, thienyl, furyl or styryl which may be substituted by one or more identical or different R.sup.5 's,R.sup.5 is phenyl, benzoyl, halogen, alkyl of 1 to 5 carbon atoms, alkyl having an --O--group and 1 to 5 carbon atoms, alkyl having an --S--group and 1 to 5 carbon atoms, alkoxyalkyl of 2 to 5 carbon atoms, alkaryl of 7 to 11 carbon atoms, aralkyl of 7 to 11 carbon atoms, NO.sub.2, CN, COOH or COOR.sup.6, R.sup.6 being an alkyl of 1 to 5 carbon atoms,A is the alkylene group C.sub.n H.sub.2n (n = an integer of 1 to 5) which may be substituted by one or more R.sup.4 's and/or R.sup.5 's, andR.sup.1, r.sup.2 and R.sup.3 may be identical or different and are each H, an R.sup.4 or an R.sup.5,and an organic amine.