摘要:
Continuous biotechnological preparation of optical isomer S(+) of 2-(6-methoxy-2-naphthyl) propionic acid consisting in the reaction of a racemic (R,S) ester of 2-(6-methoxy-2-naphthyl) propionic acid having melting point below 50.degree. C. of formula: ##STR1## wherein R.sub.1 =a C.sub.2 -C.sub.10 alkyl, C.sub.4 -C.sub.6 cycloalkyl, phenyl, tetrahydropyranyl , tetrahydrofuranyl radicals and--(CH.sub.2 CH.sub.2 O).sub.n --R.sub.2 group, whereinn=2-15 andR.sub.2 =a C.sub.1 -C.sub.4 alkyl group, with the Lipase obtained from Candida Cylindracea, at temperatures ranging from 20.degree.-60.degree. C. and at a pH ranging from 5 to 8, by feeding said ester in a continuous way into a bioreactor containing said Lipase immobilized on a porous carrier selected from adsorbent resins of the polyacrylester type having a porosity ranging from 50 to 1000 .ANG. and a granulometry ranging from 1 to 0.01 mm.
摘要:
A process is described for the separation of the optical isomers of alphayl- or alpha-aryloxy- carboxylic acids by means of the stereoselective hydrolysis of racemic alkyl esters of the above acids in the presence of bacteria or their enzymes, selected from the species Brevibacterium, Bacteridium, Micrococcus, and Bacillus.
摘要:
A process is described for separating the optical isomers of 1,2-isopropylideneglycerol, of formula (I), comprising partially stereoselective enzymatic hydrolysis of 1,2-isopropylideneglycerol benzoyl ester (II) catalyzed by a free or immobilized lipase, the hydrolysis being conducted in the presence of a cosolvent and followed by crystallization enabling crystals of (II) in raceme form and mother liquor containing (II) in the form of the pure enantiomer to be selectively obtained.The compound (I) is widely used industrially as an intermediate in the synthesis of chiral drugs such as (R)-(-)-carnitine, (S)-beta-blockers, (S)-antiviral agents, analgesic drugs etc.
摘要:
7-amino-cephalosporanic acids having the formula ##STR1## are obtained by submitting compounds having the following formula to enzymatic conversion: ##STR2## wherein R represents H, OH, O--CO--R", R" being an alkyl radical with from 1 to 4 carbon atoms, R.sup.1 represents a carboxylic group. The reaction is carried out in the presence of a microorganism selected from the Pseudomonas, Bacillus, Achromobacter genera, or in the presence of an enzyme, either free or immobilized, derived therefrom.
摘要:
The optical isomers of racemic 1,2-diols are separated by enzymatic way, byeans of a process involving the following operations:reaction of the racemic mixture of the 1,2 diols with an organic anhydride in the presence of enzyme belonging to the class of lipases;separation of the enzyme;removal of the excess of anhydride;separation of the produced esters, in optically pure form by column chromatography;recovery of the 1,2 diols, as optically pure enantiomers.
摘要:
The biotechnological resolution by means of stereoselective enzymatic thio-transesterification of the racemic mixture of the optical isomers of the compounds of formula (I): ##STR1## wherein: R, R' and R", alike or different form one another, represent a linear alkyl group of from C.sub.1 to C.sub.4, in the presence of an alcohol and an enzyme capable of selectively causing the reaction of thio-transesterification of the (L)-isomer to take place, with the (D)-isomer remaining substantially unchanged, and being then separated by means of per se known techniques.
摘要:
There is disclosed a process for the biotechnological resolution, by enzymatic esterification of the corresponding racemic mixture of the S(+) and R(-) optical isomers of the oxazolidinonic compounds having formula (I): ##STR1## wherein R represents a, linear or branched, C.sub.1 -C.sub.8 alkyl group, which process is characterized in that, the racemic 3-alkyl-5-hydroxymethyl-oxazolidin-2-one derivative of formula (I) is reacted with an esterifying compound, selected from esters having formula (III): ##STR2## wherein R represents a, linear or branched, C.sub.1 -C.sub.10 alkyl or alkenyl group and R" represents a linear or branched, C.sub.1 -C.sub.4 alkyl, alkenyl group, a haloalkyl (chlorine, bromine) group or a diacyl glycerolic group or from acids having formula (IV):R'"--COOH (IV)wherein R'" represents a, linear or branched, C.sub.1 -C.sub.20 alkyl or alkenyl group or from anhydrides having formula (V): ##STR3## wherein R.sup.IV represents a, linear or branched, C.sub.1 -C.sub.6 alkyl group, in the presence of an enzyme, immobilized on a porous carrier, capable of giving rise selectively to the esterification reaction of the R(-) isomer, while leaving the S(+) isomer substantially unchanged, which latter is then separated according to known techniques.
摘要:
Biotechnological resolution by means of enzymatic transesterification of the relevant racemic mixture of the optical isomers of .alpha.-alkyl-substituted primary alcohols having the formula (I): ##STR1## wherein: R represents a linear or branched (C.sub.1 -C.sub.20)-alkyl or alkenyl group or an aryl group, also substituted or condensed with other groups, in particular a group of formula (II) or (III): ##STR2## wherein: R.sup.ii represents a (C.sub.1 -C.sub.8)-alkyl group, a (C.sub.1 -C.sub.4)-alkenyl group, an alkoxy, phenyl, phenoxy, benzoyl, or heterocyclic group;R.sup.iii represents a hydrogen or halogen atom;R.sup.iv represents a (C.sub.1 -C.sub.4)-alkyl group, and whereinR.sup.i represents a (C.sub.1 -C.sub.4)-alkyl group either equal to, or different from, R,in the presence of an enzyme either free or immobilized on a support capable of selectively causing the S isomer to be esterified, with the R isomer being left substantially unchanged, said isomers being then separated according to techniques known from the prior art. The process is used in the synthesis of antiinflammatory agents.
摘要:
Nanoparticles with a patterned ligand coat can bind ions selectively. The ligand patterning can arise via self-assembly when two chemically dissimilar (e.g., in size and/or hydrophilicity) ligands are used together. One of the ligands can include one or more moieties capable of interacting with an ion, such as ether oxygens, hydroxyl groups, amine nitrogens, or other groups having a lone pair of electrons. Ion binding can be both selective and reversible.
摘要:
A process is described for the treatment of water contaminated by metals with a high oxidation degree, aliphatic compounds, aromatic compounds, halogen-aromatic compounds, chlorinated alkane and alkene compounds or mixtures thereof, which consists in circulating the contaminated water through a reactive system consisting of metallic iron and a zeolite having a silica/alumina ratio>50, placed in succession, wherein the first element through which the water passes is iron.