- PROCESS FOR PRODUCTION OF VITAMIN A
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The present invention relates to a new process for the production of vitamin A and/or its derivatives.
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Page/Page column 14
(2021/10/11)
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- PROCESS FOR PRODUCTION OF NEW SULFOLENIC INTERMEDIATES
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The present invention relates to a new process for the production of new specific intermediates, which are preferably used in the production of vitamin A, vitamin A acetate, or β-carotene and derivatives thereof, e.g. canthaxanthin, astaxanthin or zeaxanthin.
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Page/Page column 12
(2021/10/11)
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- Preparation method of vitamin A acetate
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The invention provides a novel preparation method of vitamin A acetate, which comprises the following steps: 1-bromo-2-chloroethane is subjected to in-situ preparation of a Grignard reagent, then the Grignard reagent reacts with pentacarbaldehyde to prepare 3-methyl-6-chloro-2, 4-hexadienol acetate, and the 3-methyl-6-chloro-2, 4-hexadienol acetate is subjected to one-step in-situ Grignard reaction and beta-ionone reaction to obtain the vitamin A acetate. The process provides a C13 + C7 vitamin A acetate synthesis route, generation of triphenylphosphine oxide is avoided, modification solid acid is used for catalysis, VA deterioration is avoided, the yield of the vitamin A acetate is improved, the process cost is reduced, the reaction process is environmentally friendly, and industrial production is facilitated. The process cost is reduced, the reaction process is environment-friendly, and industrial production is facilitated.
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Paragraph 0017; 0047; 0049-0050; 0052-0053; 0055-0056; 0058
(2021/06/21)
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- Preparation method of vitamin A acetate
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The invention provides a preparation method of vitamin A acetate, which comprises the following steps: reacting bromoethanol with acetone to obtain a ketal compound, preparing a Grignard reagent fromthe ketal compound, reacting the Grignard reagent with C5 aldehyde to obtain heptanol, reacting the heptanol with triphenylphosphine to prepare heptacarbon phosphine salt, and further reacting the heptacarbon phosphine salt with ionone to obtain the vitamin A acetate. According to the present invention, a C13 + C7 vitamin A acetate synthesis route is provided, such that the yield of the vitamin Aacetate is improved, the process cost is reduced, and the industrial production is easily achieved.
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- Preparation method of vitamin A acetate
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The invention discloses a preparation method of vitamin A acetate. Thepreparation method is characterized in that raw materials including vinyl ionol, an organic phosphine compound and pentacarbonaldehyde react under the action of a catalyst to generate vitamin A acetate, and the vitamin A acetate is synthesized by adopting a one-step method. According to the invention, the problems of considerable byproducts, serious equipment corrosion and the like caused by a liquid acid catalyst in a reaction are avoided; and meanwhile, the defects of large dosage of a base catalyst, difficulty in waste alkali treatment and the like are overcome.
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Paragraph 0028; 0042; 0047-0048; 0053-0054; 0059-0060; 0065
(2021/06/02)
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- Preparation method of vitamin A acetate intermediate C15 and vitamin A acetate
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The invention provides a preparation method of a vitamin A acetate intermediate C15 and vitamin A acetate. The method comprises the following steps: taking 1-halogenated-2-methyl-4-acetoxy-2-butene asa raw material, preparing a corresponding Wittig reagent through a substitution reaction with triphenylphosphine or triester phosphite, then carrying out a Wittig reaction with beta-cyclocitral, hydrolyzing an ester group under an alkaline condition, acidifying to obtain a corresponding halide, and carrying out a substitution reaction with triphenylphosphine or triester phosphite again to prepareC15. The vitamin A acetate can be prepared by carrying out a Wittig reaction on the obtained C15 and 2-methyl-4-acetoxy-2-butenal under an alkaline condition. The method has the advantages of singlereaction type, easy operation and realization of reaction conditions, safe and environment-friendly operation, simple post-treatment and low cost; and the reaction activity is strong, the reaction selectivity is high, the atom economy is high, and the target product yield and purity are high.
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- Preparation method of vitamin A and vitamin A ester
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The invention provides a novel method for preparing vitamin A and vitamin A ester with farnesene as a raw material. The method comprises the following steps: reacting farnesene with acetoacetate underthe action of a catalyst to obtain farnesyl keto ester; carrying out a cyclization reaction and a dehydrogenation reaction on farnesene acetone, and then reacting a reaction product with vinyl magnesium halide to generate vinyl alcohol; carrying out a rearrangement reaction on vinyl alcohol to obtain vitamin A; and subjecting the vitamin A to an esterification reaction to obtain the vitamin A ester. The method avoids the defects of the existing processes, and the process line of the method is economical and effective.
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Paragraph 0019; 0065; 0072; 0073; 0078; 0081; 0088
(2020/04/02)
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- Method for preparing vitamin A and vitamin A ester
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The invention provides a novel method for preparing vitamin A and vitamin A ester by taking farnesol as a raw material. The method comprises the following steps: carrying out oxidation reaction on farnesol and oxygen under the action of a catalyst and a cocatalyst to generate farnesal; carrying out dehydrogenation reaction on farnesal to generate dehydrofarnesal; carrying out cyclization reactionon the dehydrofarnesal under the catalysis of acid to generate a cyclized intermediate; carrying out a reaction on the cyclized intermediate with chloroisopentenol to generate vitamin A; carrying outan esterification reaction on vitamin A to generate vitamin A ester. The method avoids the defects of an existing process, and the process line is economical and effective.
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Paragraph 0061; 0066; 0079; 0086
(2020/04/17)
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- ISOMERIZATION OF POLYUNSATURATED NON-AROMATIC COMPOUNDS
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The invention relates to an improved process for isomerizing polyunsaturated non-aromatic compounds including acyclic conjugated polyenes and alicyclic conjugated polyenes. In particular it relates to an improved and safe process for forming a 11-E retinoid compounds in high yield by expending as few energy as possible and with avoiding at most possible side products or product mixtures. This is achieved by feeding at least one of retinoid compounds of formula 2 to 5, or at least one of retinoid compounds of formula 2 to 5 and retinoid compound of formula 1, an organic solvent and a photosensitizer into a reaction device and irradiating the thus obtained reaction mixture with visible monochromatic light, at least 90 % of the power of said monochromatic light and at most 100 % of said power being emitted in the range from 460 nm to 580 nm.
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Page/Page column 28
(2020/12/29)
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- Preparation method of vitamin A acetate
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The invention belongs to the field of organic synthesis and discloses a method for preparing vitamin A acetate. The method comprises the following steps that: in the presence of crown ether, a first Wittig reaction is carried out on C14 aldehyde trans-2-methyl-4-(2, 6, 6-trimethyl-1-cyclohexene)-2-butenal and C1 phosphate (tetraethyl methylenediphosphate or tetramethyl methylenediphosphate) in thepresence of organic alkali to obtain a material containing C15 phosphate, wherein R is selected from C1-C3 alkyl groups, preferably ethyl groups; and (2) the material containing C15 phosphate obtained in the step (1) and C5 aldehyde 2-methyl-4-acetoxy-2-butenal are subjected to a second Wittig reaction so as to obtain a reaction liquid containing the vitamin A acetate. The method has the advantages of environmental friendliness and high yield, and provides convenience for large-scale production of the vitamin A acetate.
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Paragraph 0066-0102
(2020/12/09)
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- SPECIFIC DEHYDROGENATION PROCESS (I)
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The present invention relates to a new dehydrogenation process of specific compounds.
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Page/Page column 11-12
(2020/10/28)
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- Preparation method of vitamin A ester intermediate C15 and vitamin A ester
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The invention provides a preparation method of a vitamin A ester intermediate C15 and vitamin A ester. The method comprises the following steps: carrying out a halogenation reaction and a cyclizationreaction on 3, 7-dimethyl-3-hydroxy-1, 6-octadiene as an initial raw material, carrying out a substitution reaction on the obtained product and triphenylphosphine or triester phosphite to prepare a corresponding Wittig reagent, carrying out a Wittig reaction on the Wittig reagent and 2-methyl-4-acetoxy-2-butenal, performing acidifying, hydrolyzing and acidifying the obtained product, and carryingout a substitution reaction on the hydrolyzed and acidified product and triphenylphosphine or triester phosphite to prepare C15. The vitamin A ester can be prepared by carrying out a Wittig reaction on the obtained C15 and 2-methyl-4-R3 substituent carbonyloxy-2-butenal. The method has the advantages of single reaction type, easy operation and realization of reaction conditions, safe and environment-friendly operation, simple post-treatment and low cost; and the reaction activity is strong, the reaction selectivity is high, the atom economy is high, and the target product yield and purity arehigh.
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- Preparation process of vitamin A intermediate and vitamin A acetate
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The invention discloses a preparation process of a vitamin A intermediate. Compared with a traditional Kuraray synthesis route, the preparation process directly carries out halogenation reaction on analcohol metal intermediate without hydrolysis in an anhydrous and oxygen-free environment, not only reduces one-step chemical reaction and shortens working procedures, but also reduces the use of reagents and solvents, at the same time also improves the utilization rate of metallization reagents, greatly reduces pollution, and improves safety and economic benefits. The invention also provides a preparation method of vitamin A acetate based on the vitamin A intermediate, and the obtained vitamin A acetate has higher purity and is easy to store.
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- Preparation method of retinyl acetate
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The invention provides a preparation method of retinyl acetate. The method comprises the following steps: performing a condensation reaction on beta-ionone and 2-chloropropionate under the action of astrong alkali, and performing hydrolysis decarboxylation to form an intermediate I; performing a condensation reaction on the intermediate I and pentaaldehyde to produce an intermediate II; and performing a hydrogenation reaction on the intermediate II under the action of a catalyst, and performing a dehydration reaction to obtain the retinyl acetate. The method provided by the invention avoids the disadvantages of a current process and has an economical and effective process route.
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- Method for preparing vitamin A acetate
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The invention belongs to the technical field of production of vitamin A and its derivatives, in particular to a method for preparing vitamin A acetate. The method comprises the following steps: (1) mixing triphenylphosphine and acid in supercritical CO2, and then contacting the obtained mixture with vinyl-beta-ionol for salt formation to obtain C15 phosphine salt; (2) after adding solvent water, ionic liquid and C5 aldehyde to the finished system of step (1) , CO2 is released for solvent replacement, and the materials are uniformly mixed; (3) adding an extractant to the system after the solvent replacement of step (2), stirring and adding an alkali solution for Wittig reaction to obtain the vitamin A acetate. The method of the invention has mild reaction conditions, safe production and easy control, and the purity and reaction yield of the final product are high.
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Paragraph 0060-0083
(2019/05/08)
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- Using imidazolium-based ionic liquids as dual solvent-catalysts for sustainable synthesis of vitamin esters: Inspiration from bio- and organo-catalysis
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Vitamin E (VE) has significant biological activities and thus its acylation to increase its stability is of extreme interest. We developed an efficient and sustainable approach using imidazolium-based ionic liquids as dual solvent-catalysts for the esterification between α-tocopherol (the most active form of VE) and succinic anhydride. Although in literature it is reported that lipase can catalyze this reaction, hereby we demonstrate that the reaction observed in DMSO and DMF is catalyzed by the histidyl residues of the protein. Histidine and its analogue containing an imidazole ring were tested as organocatalysts for the production of α-tocopherol succinate. In light of the imidazole organocatalysis, commercially-available 3-alkyl-1-methyl imidazolium ILs [CnC1Im][X-] were investigated as dual solvent-catalysts for the esterification of α-tocopherol with succinic anhydride, and provided satisfactory yields and reaction rates. [C5C1Im][NO3-] can be recycled by water extraction, instead of organic solvent extraction to separate α-tocopherol succinate from [C5C1Im][NO3-], with an average yield of 94.1% for 4 subsequent batches, while the catalytic activity of the recycled ILs showed almost no loss after 4 batches. The developed protocol for the synthesis of α-tocopherol esters and IL recycling bears industrial potential due to the ease of use and the efficient recycling.
- Tao, Yifeng,Dong, Ruijuan,Pavlidis, Ioannis V.,Chen, Biqiang,Tan, Tianwei
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supporting information
p. 1240 - 1248
(2016/03/09)
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- Method for producing vitamin a acetate
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The present invention relates to a process for preparing vitamin A acetate by reacting β-vinylionol with triphenylphosphine in the presence of sulfuric acid in a solvent mixture consisting of 60 to 80% by weight methanol, 10 to 20% by weight water and 10 to 20% by weight aliphatic, cyclic or aromatic hydrocarbons having 5 to 8 carbon atoms to give β-ionylideneethyltriphenylphosphonium salts and subsequent Wittig reaction with 4-acetoxy-2-methylbut-2-enal.
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- METHOD FOR PRODUCING VITAMIN A ACETATE
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The invention relates to a method for producing vitamin A acetate by reacting β-vinyl ionol with triphenylphosphine in the presence of sulphuric acid in a solvent mixture consisting of between 60 and 80 % methanol, between 10 and 20 % water and between 10 and 20 wt. % aliphatic, cyclic or aromatic hydrocarbons with between 5 and 8 atoms, in order to obtain β-ionylidene ethyltriphenyl phosphonium salts and then by a subsequent Wittig reaction using 4-acetoxy-2-methyl-but-2-enal.
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Page/Page column 7
(2008/06/13)
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- General and systematic synthetic entry to carotenoid natural products
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A general synthetic method of carotenoid natural products has been developed, in which the systematic chain extension and termination processes were applied. The syntheses of the chain extension and termination units were greatly improved by the use of the common intermediate, 1-bromo-4-chloro-3- methyl-2-butene (8), in a short and highly efficient way. The C10 chain initiation β-cyclogeranyl sulfone (3) was coupled with the C 5 chain extension unit to give the C15 chain-extended allylic sulfone after chemoselective sulfide oxidation. This chain-extended C15 allylic sulfone underwent the Julia olefination reaction with the C5 and the C10 chain termination units to give retinol (1) and β-carotene (2), respectively. Graphical Abstract
- Cheol Jeong, Young,Ji, Minkoo,Sup Lee, Jun,Yang, Jae-Deuk,Jin, Jingquan,Baik, Woonphil,Koo, Sangho
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p. 10181 - 10185
(2007/10/03)
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- Process for preparation of allyl sulfone derivatives and intermediates for the preparation
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The present invention relates to a process for producing an allyl sulfone derivative represented by the formula (3): wherein Ar is an optionally substituted aryl group, and the corrugated line means either one of E/Z geometrical isomers, or a mixture thereof, which is an intermediate for producing vitamin A, which process is characterized by reacting an aryl sulfinic acid or a salt thereof represented by the formula (2): ArSO2M (2) wherein Ar is as defined above, and M is hydrogen atom, sodium atom or potassium atom, with an allyl halide derivative represented by the formula (1): wherein X is a halogen atom, and Ar and the corrugated line are as defined above.
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- Process for producing retinol and intermediate compounds for producing the same
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There are disclosed a disulfone compound of formula (1): wherein Ar denotes an aryl group that may have a substituent, R1 denotes a hydrogen atom or a protective group of a hydroxyl group and the wavy line means that the disulfone compound is an E or Z geometrical isomer or a mixture thereof, a method for producing the same, intermediate compounds therefore and a process for producing retinol through the disulfone compound.
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- Vitamin a related compounds and process for producing the same
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There is provided a compound of the formula[I]: wherein R represents a hydrogen atom or a protective group for a hydroxyl group; andA represents a hydrogen atom, a halogen atom or a group of the formula A1: Q represents Q3: when A represents a halogen atom or a protective group for a hydroyl group, A represents Q4: ?wherein R1 and R2 represent a hydrogen atom or a protective group for a hydroxyl group; and when A represents a hydrogen atom, Q is Q2:
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Page column 12
(2010/01/30)
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- Process for producing retinol and intermediate compounds for producing the same
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There are disclosed a disulfone compound of formula (1): wherein Ar denotes an aryl group that may have a substituent, R1 denotes a hydrogen atom or a protective group of a hydroxyl group and the wavy ine means that the disulfone compound is an E or Z geometrical isomer or i mixture thereof,a method for producing the same,intermediate compounds therefore anda process for producing retinol through the disulfone compound.
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- Process for producing vitamin a ester
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The invention relates to a process for producing all trans-vitamin A ester (I). According to the present invention, vitamin A ester (I) can simply be synthesized in good yields and high purity by the reaction of phosphonate compound (IV) with aldehyde (II) in an organic solvent in the presence of a base.
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- The organoalkali route to vitamin A and β-carotene
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The reductive cleavage of methyl vinyl-β-ionyl ether (1) or the deprotonation of 3,2′,6′,6′-tetramethyl-5-(1-cyclohexenyl)-1, 3-pentadiene (2) gives rise to an organometallic C15 species that combines selectively with a variety of electrophiles at the terminal chain position. Its reaction with aldehydes, however, is less clean. In particular, (E)-β-formyl-2-butenyl acetate gives the expected adduct 7a and, after dehydration, vitamin A acetate only in poor yield. The same is true for the analogous reaction with 2,7-dimethyl-2,4,6-octatriendial, which ultimately affords βcarotene. Vitamin A acetate can also be prepared, this time in moderate yield, by functionalization through consecutive deprotonation, borylation, oxidation and acetylation of a C20 pentaene hydrocarbon having the required skeleton. Both the C15 and the C20 organometallic key intermediates adopt spontaneously a zigzag-like outstretched conformation which, upon electrophilic trapping, directly and exclusively leads to the all-(E) configuration.
- Rauchschwalbe, Guenter,Zellner, Armin,Schlosser, Manfred
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p. 3903 - 3909
(2007/10/03)
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- Dihalo-compound and process for producing vitamin A derivative
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There is disclosed a dihalo-compound of formula (1): wherein X1 and X2 represent different halogen atoms, R represents a hydrogen atom or a protective group for a hydroxyl group, and a process for producing vitamin A derivative via a sulfone derivative of formula (5): wherein Ar represents an optionally substituted aryl group, and R represents the same as defined above.
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- Manufacture of cycloalkenylpolyene esters
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The invention provides a process for the manufacture of a retinyl acylate of the formula I: wherein R1is an optionally substituted C1-23-alkyl, a C2-23-alkenyl having 1 to 5 double bonds, an optionally aromatically substituted phenyl-C1-6-alkyl, or an optionally substituted phenyl. This process includes treating a compound of formula II: wherein R1is defined above and R2is hydrogen or COR1, with an agent that is an acid anhydride or a complex of sulfur trioxide in the presence of dimethylformamide. In addition to dimethylformamide, an aprotic organic solvent may optionally be present in the reaction. The products of the present invention are useful as intermediates for the manufacture of compounds of the vitamin A group or in certain cases as the compounds themselves.
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- Process for producing vitamin A derivatives
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The present specification relates to an industrially advantageous process for producing vitamin A derivatives which are useful as medicaments, feed additives, food additives and the like. The process provides vitamin A derivatives, particularly all-trans vitamin A derivatives in high yield and purity.
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- Intermediates for preparing vitamins A and E and carotenoids
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The present invention relates to a new method of condensing polyenic compounds wherein a compound having the formula III STR1 is condensed with a compound having the formula IV STR2 under the influence of a Lewis acid or a protic acid. R1 through R7 represent alkyl or alkenyl groups, A' is preferably chlorine, B is preferably a hydroxyl group, and n' is 0 to 10. The invention also relates to novel intermediates for use in the preparation of Vitamins A and E produced by means of the new method.
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- PMR STUDY OF REACTION OF 10,15-DIHYDROXY-9,13-DIMETHYL-7-(1,1,5-TRIMETHYL-5-CYCLOHEX-6-ENYL)-8,11,13-NONATRIENE ACETATES WITH HYDROCHLORIC ACID
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Dehydration of acetylated 10,15-dihydroxy-9,13-dimethyl-7-(1,1,5-trimethyl-5-cyclohex-6-enyl)-8,11,13-nonatriene by hydrochloric acid gives as intermediate products a mixture of 8-chloro- and 14-chloroacetates whose proportion depends on the solvent used in the reaction.Dehydrochlorination turns 8-chlorine derivatives into 14-chlorine derivatives from which vitamin A acetate is then formed.The precursor of 13-Z-retinyl acetate seems to be 11-E,13-isomer of 8-chloroacetate.A general conversion scheme is proposed and the reaction rate constants are determined.
- Filippova, T. M.,Mairanovskii, V. G.,Shmyrev, I. K.,Gutnikova, N. P.,Zakharova, N. I.,et al.
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p. 2165 - 2175
(2007/10/02)
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- Preparation of (7Z) - and (7Z,11Z) - Vitamin A
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An efficient access to (7Z)- and (7Z,11Z)-vitamin A is described. Following the addition of a C6-acetylenic building block to 2,6,6-trimethylcyclohexanone (2), dehydration of the tert. alcohol 3 and formation of the C15-Wittig salt, the (7Z)-geometry was introduced by partial hydrogenation of the triple bond over Raney-nickel. Following Wittig reaction with (E)-2-methyl-4-acetoxy-2-butenal gave a mixture of the title compounds 8 and 9 which could easily be separated.
- Soukup,Widmer
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p. 4117 - 4118
(2007/10/02)
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- Process for producing vitamin A or its carboxylic acid esters
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The invention provides a process for producing vitamin A or its carboxylic acid ester by treating inexpensive and readily available industrial starting materials with potassium hydroxide which is widely employed industrially and is inexpensive.
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- Process for producing halogenated sulfone
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The present invention provides a process for preparing halogenated sulfones by reacting a halogenating agent with a salt of a hydroxysulfone. The halogenated sulfones are useful as an intermediate for vitamin A or its carboxylic acid esters employed as medicines or feed additives.
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- Process for producing vitamin A or its carboxylic acid esters, and intermediate compounds useful for the process
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A process for producing vitamin A represented by the formula STR1 which comprises treating a compound represented by the formula STR2 wherein R1 represents an aryl group which may be substituted, R21 and R22 each represents a hydrogen atom or a lower alkanoyl group, R3 represents an acetal-type protective group for a hydroxyl group, and X represents a halogen atom, with a base; and novel intermediate compounds useful for the above process.
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- THE HIGHLY STEREOSELECTIVE SYNTHESIS OF ALL-TRANS AND 13-CIS VITAMIN A VIA DOUBLE ELIMINATION REACTION
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Stereocontrolled convergent synthesis of vitamin A was achieved by the double elimination method employing the C10 sulfone and the C10 aldehydes as starting materials.Thus the all-trans and 13-cis isomers were obtained with the stereochemical purity of 95percent and 90percent, respectively.
- Otera, Junzo,Misawa, Hiromitsu,Mandai, Tadakatsu,Onishi, Takashi,Suzuki, Shigeaki,Fujita, Yoshiji
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p. 1883 - 1886
(2007/10/02)
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- Electro-organic Reactions. Part 20. Electrogenerated Bases, Ylide Formation, and Wittig Alkene Synthesis
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Dicyano(fluoren-9-ylidene)methane (1a), dicyano(2,7-dibromofluoren-9-ylidene)methane (1b), and ethyl 2-cyano-2-fluoren-9-ylideneacetate (1c) may be cathodically reduced in N,N-dimethylforamide to give dianions which efficiently convert phosphonium salts into ylides.The potentials required are sufficiently modest to allow the electrogeneration of the bases in the presence of several phosphonium salts and of several aldehydes to give a convenient method of carrying out the Wittig alkene synthesis.This method has been explored for the synthesis of stilbene, 1,4-diphenylbutadiene, and vitamin A acetate.The basicity of the dianions varies according to the choice of electrolyte cation (Bu4N+ or Li+).The cations also have a marked effect on the stereochemical course of the reaction and, in particular, mixtures of alkenes are obtained in which the cis-isomer predominates in the presence of lithium ion; in the vitamin A acetate synthesis, the 11-cis-isomer constitutes 76percent of the product.The results are consistent with recent hypotheses concerning the mecahnism of the Wittig reaction.
- Mehta, Raj R.,Pardini, Vera L.,Utley, James H. P.
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p. 2921 - 2926
(2007/10/02)
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- Transient Phenomena in the Pulse Radiolysis of Retinyl Polyenes. 1. Radical Anions
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The spectra and kinetics of formation and decay of radical anions of a number of retinyl polyenes have been studied in methanol and 2-propanol at room temperature, using pulse radiolysis and kinetic spectrophotometry.The bimolecular rate constants for the attachment of solvated electrons, e-MeOH, to the retinyl polyenes are in the diffusion-controlled limit (8.6 x 109-1.6 x 1010 M-1 s-1).The radical anions of retinol and retinol acetate have their spectral maxima at 370-390 nm, and undergo decay very slowly with second-order kinetics.On the other hand, the radical anions of retinal, retinal n-butylamine Schiff base, and retinoic acid/ester have spectral maxima at 430-510 nm, and decay by first-order kinetics in methanol with rate constants in the range 1 x 104-1 x 106 s-1.The decay rates of radical anions of retinal and retinoic acid/ester become considerably longer on going from methanol to less acidic alcohol, 2-propanol, suggesting that protonation by solvent is the major mode of their decay in protic media.In the case of retinal Schiff base, an additional slow process with bimolecular rate constant 9.0 x 107 M-1 s-1 im methanol is observed for the formation of radical anion and is ascribed to the electron-transfer reaction from the methanol radical, .CH2OH.
- Raghavan, N.V.,Das, P.K.,Bobrowski, K.
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p. 4569 - 4573
(2007/10/02)
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- Treatment of methanolic-aqueous residues from syntheses employing triphenylphosphonium salts
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A process for treating residues which result from the Wittig synthesis of olefins and which consist principally of methanol, triphenylphosphine oxide, salts and organic by-products, by steam-stripping the volatile constituents, with partial condensation of the steam, and separating the resulting aqueous-organic mixture at 80°-100° C. into a saline aqueous phase and an organic phase containing principally triphenylphosphine oxide. Using this process provides a simple method of freeing, from triphenylphosphine oxide and other organic impurities, the effluent from syntheses which result in the formation of triphenylphosphine oxide, and thereby on the one hand substantially facilitates the purification of the effluent and on the other hand provides a simple method of recovering the triphenylphosphine oxide. The latter compound, which is easily purified by distillation or recrystallization, can then be used, for example, to prepare the triphenylphosphine required for Wittig syntheses or to prepare the triphenylphosphine dichloride required for the synthesis of pesticides.
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- Process for producing vitamin A
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A process for producing vitamin A esters, vitamin A aldehyde and vitamin A acid esters from esters of 3,7-dimethyl-9-(1-hydroxy-2,2,6-trimethylcyclohexyl)-nona-2,4,6-trien-8-yn-1-ol and 3,7-dimethyl-9-(1-hydroxy-2,2,6-trimethylcyclohexyL)-nona-2,4,6-trien-8-ynoic acid including intermediates in this process.
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- Preparation of carotenoids using a ?-allyl complex
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A novel procedure for the preparation of carotenoids, particularly vitamin A, employing ?-allyl transition metal complexes. Novel carotenoid intermediates are also disclosed.
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- Isomerization process
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A process for isomerizing vitamin A and derivatives thereof utilizing either palladium or a palladium containing compound as a catalyst.
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- Process for producing a sulfone derivative of vitamin A alcohol
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A process for the preparation of vitamin A and esters thereof from the condensation of a sulfone of 2-methyl-4-hydroxy-but-2-ene and an activated derivative of 3-methyl-5-(2,6,6-trimethyl-cyclohexen-1-yl)penta-2,4-diene including intermediates therein.
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