The present invention discloses an improved process for extracting cholesterol in high yield and purity from fish oil waste residue. The so obtained cholesterol of pharmaceutical grade is useful as a precursor for the preparation of vitamin D3.

The present invention relates to a process for the preparation of an optically active carbonyl compound by asymmetric hydrogenation of a prochiral α,β-unsaturated carbonyl compound with hydrogen in the presence of at least one optically active transition metal catalyst that is soluble in the reaction mixture and which has rhodium as catalytically active transition metal and a chiral, bidentate bisphosphine ligand, wherein the reaction mixture during the hydrogenation of the prochiral α,β-unsaturated carbonyl compound additionally comprises at least one compound of the general formula (I): ##STR00001## in which R.sup.1, R.sup.2: are identical or different and are C.sub.6- to C.sub.10-aryl which is unsubstituted or carries one or more, e.g. 1, 2, 3, 4 or 5, substituents which are selected from C.sub.1- to C.sub.6-alkyl, C.sub.3- to C.sub.6-cycloalkyl, C.sub.6- to C.sub.10-aryl, C.sub.1- to C.sub.6-alkoxy and amino; Z is a group CHR.sup.3R.sup.4 or aryl which is unsubstituted or carries one or more, e.g. 1, 2, 3, 4 or 5, substituents which are selected from C.sub.1- to C.sub.6-alkyl, C.sub.3- to C.sub.6-cycloalkyl, C.sub.6- to C.sub.10-aryl, C.sub.1- to C.sub.6-alkoxy and amino, wherein R.sup.3 and R.sup.4 are as defined in the claims and the description.

The present invention relates to a process for the preparation of an optically active carbonyl compound by asymmetric hydrogenation of a prochiral α,β-unsaturated carbonyl compound with hydrogen in the presence of at least one optically active transition metal catalyst that is soluble in the reaction mixture and which has rhodium as catalytically active transition metal and a chiral, bidentate bisphosphine ligand, wherein the reaction mixture during the hydrogenation of the prochiral α,β-unsaturated carbonyl compound additionally comprises at least one compound of the general formula (I): ##STR00001## in which R.sup.1, R.sup.2: are identical or different and are C.sub.6- to C.sub.10-aryl which is unsubstituted or carries one or more, e.g. 1, 2, 3, 4 or 5, substituents which are selected from C.sub.1- to C.sub.6-alkyl, C.sub.3- to C.sub.6-cycloalkyl, C.sub.6- to C.sub.10-aryl, C.sub.1- to C.sub.6-alkoxy and amino; Z is a group CHR.sup.3R.sup.4 or aryl which is unsubstituted or carries one or more, e.g. 1, 2, 3, 4 or 5, substituents which are selected from C.sub.1- to C.sub.6-alkyl, C.sub.3- to C.sub.6-cycloalkyl, C.sub.6- to C.sub.10-aryl, C.sub.1- to C.sub.6-alkoxy and amino, wherein R.sup.3 and R.sup.4 are as defined in the claims and the description.

The present invention relates to a process for the preparation of an optically active carbonyl compound by asymmetric hydrogenation of a prochiral α,β-unsaturated carbonyl compound with hydrogen in the presence of at least one optically active transition metal catalyst that is soluble in the reaction mixture and which has rhodium as catalytically active transition metal and a chiral, bidentate bisphosphine ligand, wherein the reaction mixture during the hydrogenation of the prochiral α,β-unsaturated carbonyl compound additionally comprises at least one compound of the general formula (I): ##STR00001## in which R.sup.1, R.sup.2: are identical or different and are C.sub.6- to C.sub.10-aryl which is unsubstituted or carries one or more, e.g. 1, 2, 3, 4 or 5, substituents which are selected from C.sub.1- to C.sub.6-alkyl, C.sub.3- to C.sub.6-cycloalkyl, C.sub.6- to C.sub.10-aryl, C.sub.1- to C.sub.6-alkoxy and amino; Z is a group CHR.sup.3R.sup.4 or aryl which is unsubstituted or carries one or more, e.g. 1, 2, 3, 4 or 5, substituents which are selected from C.sub.1- to C.sub.6-alkyl, C.sub.3- to C.sub.6-cycloalkyl, C.sub.6- to C.sub.10-aryl, C.sub.1- to C.sub.6-alkoxy and amino, wherein R.sup.3 and R.sup.4 are as defined in the claims and the description.

Provided is a preparation method for a cyclohexane dimethanol (CHDM), which can have a high trans content through particular conditions, additive addition, or reactant addition, which is controlled in a cyclohexane dicarboxylic acid (CHDA) hydrogenation reaction, and a cyclohexane dimethanol prepared thereby.

Provided is a preparation method for a cyclohexane dimethanol (CHDM), which can have a high trans content through particular conditions, additive addition, or reactant addition, which is controlled in a cyclohexane dicarboxylic acid (CHDA) hydrogenation reaction, and a cyclohexane dimethanol prepared thereby.

Provided is a preparation method for a cyclohexane dimethanol (CHDM), which can have a high trans content through particular conditions, additive addition, or reactant addition, which is controlled in a cyclohexane dicarboxylic acid (CHDA) hydrogenation reaction, and a cyclohexane dimethanol prepared thereby.

The present invention relates to a method for preparing p-menthane-3,8-diol, characterised in that it comprises the following steps:

a. preparation of an aqueous solution comprising between 0.05% and 5% by mass, preferably between 0.05% and 2% by mass, preferentially between 0.05% and 1% by mass, even more preferentially between 0.05% and 0.5% by mass of an ammonium salt, the said ammonium salt being characterised in that it is selected from the group formed by an amino acid ammonium salt, and in particular an amino acid hydrochloride, a vitamin B ammonium salt, and in particular a vitamin B hydrochloride, an ammonium salt of an amino acid ester, and an ammonium salt of a vitamin B ester, or is defined by the following formula (I):

##STR00001##

wherein R.sub.1 represents a benzyl, optionally substituted, or R.sub.1 represents an alkyl, either linear or branched, optionally cyclical, saturated or unsaturated, optionally substituted, comprising from 1 to 10 carbon atoms, preferably from 1 to 6 carbon atoms, preferentially from 2 to 4 carbon atoms, and R.sub.2, R.sub.3 and R.sub.4 represent a hydrogen or a methyl group, and X represents a chlorine atom, bromine atom or an OR′ group, R′ being an alkyl group comprising from 1 to 10 carbon atoms,

b. adding of citronellal to the aqueous solution obtained in the step a), and obtaining a mixture;

c. stirring and heating of the mixture obtained in the step b);

d. decanting of the reaction medium obtained at the end of step c) and obtaining at least two phases; and

e. separation of the said at least two phases obtained in the step d), and obtaining at least one aqueous phase and at least one organic phase, the said organic phase comprising at least p-menthane-3,8-diol.

The present invention relates to a method for preparing p-menthane-3,8-diol, characterised in that it comprises the following steps:

a. preparation of an aqueous solution comprising between 0.05% and 5% by mass, preferably between 0.05% and 2% by mass, preferentially between 0.05% and 1% by mass, even more preferentially between 0.05% and 0.5% by mass of an ammonium salt, the said ammonium salt being characterised in that it is selected from the group formed by an amino acid ammonium salt, and in particular an amino acid hydrochloride, a vitamin B ammonium salt, and in particular a vitamin B hydrochloride, an ammonium salt of an amino acid ester, and an ammonium salt of a vitamin B ester, or is defined by the following formula (I):

##STR00001##

wherein R.sub.1 represents a benzyl, optionally substituted, or R.sub.1 represents an alkyl, either linear or branched, optionally cyclical, saturated or unsaturated, optionally substituted, comprising from 1 to 10 carbon atoms, preferably from 1 to 6 carbon atoms, preferentially from 2 to 4 carbon atoms, and R.sub.2, R.sub.3 and R.sub.4 represent a hydrogen or a methyl group, and X represents a chlorine atom, bromine atom or an OR′ group, R′ being an alkyl group comprising from 1 to 10 carbon atoms,

b. adding of citronellal to the aqueous solution obtained in the step a), and obtaining a mixture;

c. stirring and heating of the mixture obtained in the step b);

d. decanting of the reaction medium obtained at the end of step c) and obtaining at least two phases; and

e. separation of the said at least two phases obtained in the step d), and obtaining at least one aqueous phase and at least one organic phase, the said organic phase comprising at least p-menthane-3,8-diol.

A reactor for performing a reaction between two immiscible fluids of different density, comprising an interior formed by a cylindrical, vertically oriented elongate shell, a bottom and a cap, wherein the interior is divided by internals into a backmixed zone, a zone of limited backmixing preferably arranged below the backmixed zone and a plug-flow zone which are at least consecutively traversable by one of the fluids, wherein the backmixed zone comprises at least one inlet and the plug-flow zone comprises an outlet and the backmixed zone comprises at least one mixing apparatus selected from a stirrer, a jet nozzle and means for injecting the fluid of lower density, a first cylindrical internal element which in the interior extends in the longitudinal direction of the reactor, which delimits the zone of limited backmixing from the plug-flow zone and which comprises a first passage to the backmixed zone and a second passage to the plug-flow zone, a second internal element which delimits the backmixed zone from the plug-flow zone such that there is no direct fluid connection between the backmixed zone and the plug-flow zone, and backmixing-preventing third internal elements in the form of random packings, structured packings or liquid-permeable trays arranged in the zone of limited backmixing. The reactor allows an optimal residence time distribution in the reaction of the two immiscible fluids of different density. The invention further relates to a process for performing a continuous reaction in the reactor.