摘要:
The current invention provides novel bifunctional catalysts. The bifunctional catalysts are prepared from phosphine ligands and a cyclopentadienyl metal complex and are useful for forming isomers of hydrocarbon species. The hydrocarbon can be an alkenol having the alkene and alcohol groups far apart and the catalyst will move the double bond across numerous carbon atoms. The hydrocarbon can also be an achiral alkenol and the catalyst will form a chiral alcohol therefrom. Moreover, deuterated water may be added to the isomerization reaction mixture for forming deuterated hydrocarbon species.
摘要:
Process for esterification of farnesol in an initial mixture comprising alpha-bisabolol, farnesol and optionally other components, with the following steps: 1. Preparation or production of the initial mixture, 2. Adding (i) a transesterification catalyst and (ii) one or more compounds of formula (B) R2YnCO2R1 (B) in which the following applies: R1 stands for an alkyl residue with 1 to 12 C atoms; R2 stands for hydrogen, an alkyl residue with 1 to 20 C atoms, a cycloalkyl residue with 5 to 20 C atoms, an aryl residue with 6 to 20 C atoms or a heteroaryl residue with 5 to 20 C atoms; and Y stands for CH2, CH(Me), CH(Et), C(Me)2, CH2—CH(Me), CH(Me)-CH2 or CH2—CH(Me)-CH2 and n stands for a whole number from 0 to 6; or R2 stands for a group CO2R3, R3 standing for an alkyl residue with 1 to 12 C atoms; and Y stands for CH2, CH(Me), CH(Et), C(Me)2, CH2—CH(Me), CH(Me)-CH2 or CH2—CH(Me)-CH2 and n stands for a whole number from 0 to 8, or Y stands for an optionally substituted phenyl or naphthyl ring with a total of at most four substituents on the ring, n=1 applying.
摘要:
A catalyst system comprising a primary catalyst chosen from one or more homogeneous or heterogeneous, inorganic, organic or complex metal-containing compound; and one or more phenolic activator/modifier(s). The catalyst system can be used for the preparation of allylic alcohols by rearrangement of corresponding epoxides, the subsequent Oppenauer type oxidation of allylic alcohols to alpha, beta-unsaturated carbonyl compounds, and/or the preparation of alpha, beta-unsaturated carbonyl compounds by rearrangement of epoxides to corresponding allylic alcohols followed by the subsequent Oppenauer type oxidation of allylic alcohols in a one pot process.
摘要:
Improved processes for preparation of high enantiomeric purity compounds center on resolution using simulated moving bed chromatography of a racemic precursor early in the synthesis. Resolution is effected with high enantiomeric purity, and subsequent reactions of the desired enantiomer performed with high optical specificity to maintain enantiomeric purity. The undesired enantiomer is racemized and recycled to the resolution phase to avoid loss.
摘要:
A process for producing l-isopulegol by simple operations with safety in high yield. A process for producing isopulegol, which comprises selectively cyclizing citronellal in the presence of a tris(2,6-diarylphenoxy)aluminum catalyst represented by the following general formula (3): 1 wherein Al represents an aluminum atom, Ar1 and Ar2 each represent a substituted or unsubstituted aryl group or a heteroaryl group; and R1, R2 and R3 each represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 8 carbon atom(s), an alkoxy group having 1 to 8 carbon atom(s), a substituted or unsubstituted aryl group, a dialkylamino group having 1 to 4 carbon atom(s), or a nitro group.
摘要翻译:通过简单的操作以高产率安全地生产l-异头孢烯的方法。 一种生产异胡醇的方法,其包括在由以下通式(3)表示的三(2,6-二芳基苯氧基)铝催化剂存在下选择性环化香茅醛:其中Al表示铝原子,Ar 1和Ar 2各自表示取代的 或未取代的芳基或杂芳基; R 1,R 2和R 3各自表示氢原子,卤素原子,碳原子数1〜8的烷基,碳原子数1〜8的烷氧基,取代或未取代的芳基, 具有1〜4个碳原子的二烷基氨基或硝基。
摘要:
The present invention relates to a process for the production of xylitol. Specifically the process comprises two reaction steps. The first step is the fermentative conversion of a hexose to a pentitol. The second step is the catalytic chemical isomerisation of the pentitol to xylitol. Optionally, the xylitol is separated from the other pentitols.
摘要:
The fixed-bed catalyst comprises palladium and selenium or tellurium or a mixture of selenium and tellurium on a silicon dioxide support and has a BET surface area of from 80 to 380 m2/g and a pore volume of from 0.6 to 0.95 cm3/g in the pore diameter range from 3 nm to 300 &mgr;m, with from 80 to 95% of the pore volume being in the pore diameter range from 10 to 100 nm. It is prepared by impregnating a silicon dioxide support with a solution of a palladium compound and a selenium compound or tellurium compound or a mixture of a selenium compound and a tellurium compound, drying it and reducing it in the presence of hydrogen. The catalyst is used, in particular, for isomerizing 3-buten-1-ol compounds.
摘要:
Allyl alcohols are isomerized in aqueous solution in the presence of protonic acids, with the pH of the reaction mixture being adjusted to the range from 2 to 5 with an acid concentration below 0.16 mol per liter of the reaction mixture or with a buffer which comprises the protonic acid.
摘要:
Improved processes for preparation of the (S)-oxetines in high enantiomeric purity centers on resolution using simulated moving bed chromatography of a racemic precursor early in the oxetine synthesis. Resolution is effected with high enantiomeric purity, and subsequent reactions of the desired enantiomer performed with high optical specificity to maintain enantiomeric purity. The undesired enantiomer may be racemized and recycled to the resolution phase to avoid undesired losses.
摘要:
Epoxides containing hydroxy groups are rearranged enantioselectively using a chiral base to give allyl alcohols in high enantiomeric excess, e.g. ##STR1## If R.sup.3 .noteq.H, the reaction also has the effect of generating a chiral tetrasubstituted carbon atom.