Method for preparing chiral citronellal through citral catalytic asymmetric hydrogenation

A catalytic hydrogenation, asymmetric technology, applied in the field of flavors and fragrances, can solve the problems of high catalyst consumption, difficult industrial application, cumbersome process, etc., and achieve the effects of high yield, easy separation, and high enantioselectivity

Active Publication Date: 2016-01-06
WANHUA CHEM GRP CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0007] Most of the above-mentioned metal catalysis methods need to control the selectivity of the reaction through the action of toxic CO gas, or need to pre-prepare a complex of carbonyl rhodium and chiral phosphine as a catalyst, the process is more cumbersome, the stability is poor, and the catalyst consumption is relatively high. High, high cost, so it is difficult to carry out industrial application

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  • Method for preparing chiral citronellal through citral catalytic asymmetric hydrogenation
  • Method for preparing chiral citronellal through citral catalytic asymmetric hydrogenation
  • Method for preparing chiral citronellal through citral catalytic asymmetric hydrogenation

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Embodiment

[0041] The embodiments of the present invention are described in detail below. This embodiment is implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific operating procedures are provided, but the protection scope of the present invention is not limited to the following implementation example.

[0042] In the following examples, the chiral rhodium complex used after coordination preparation in the following examples is expressed as [Rh(L*)(L)]X, and can also be obtained by rhodium salts with anion and auxiliary ligand [ Rh(L) 2 ]X or [RhX(L)] 2 In situ coordination synthesis with chiral ligand L*.

[0043] Gas chromatograph: Agilent7890, column Supelcoβ-DEX TM 225, inlet temperature: 220°C; split ratio 50:1; heating program: initial temperature 100°C; rise to 120°C at a rate of 5°C / min, hold for 0min; rise to 200°C at a rate of 20°C / min , keep for 7min, detector temperature: 300°C;

[0044] as attache...

Embodiment 1

[0047] Preparation of chiral citronellal

[0048] In a 10 mL reaction tube, add the phosphine ligand R-L1a (3.5 mg, 0.005 mmol) and bis(1,5-cyclooctadiene) rhodium tetrafluoroborate [Rh(COD) 2 ] BF 4 (2.1mg, 0.005mmol), the system passed through the vacuum line, replaced with nitrogen three times, added freshly steamed degassed toluene (2mL), the solution was stirred at room temperature for 1 hour, and the solvent was removed under reduced pressure to obtain a brown solid, which was vacuum pumped for 2 After 1 hour, 2 mL of methanol solvent was added, and this solution was added to BF containing E-citral (76.1 mg, 0.50 mmol, E / Z=99 / 1, chiral rhodium complex [Rh(R-L1a)(COD)] 4 The molar ratio of citral is 1 / 100) and sodium iodide (7.5mg, 0.05mmol) into a vial, put it into an autoclave, and after 6 hydrogen replacements, the initial hydrogen pressure is 20bar, and the reaction is stirred at 15°C for 24 Hour. Cool, release gas carefully, open the autoclave, take out the vial, ...

Embodiment 2

[0050] Preparation of chiral citronellal

[0051] In a 10mL reaction tube, add the phosphine ligand S-L1b (4.1mg, 0.005mmol) and rhodium bis(1,5-cyclooctadiene)tetrafluoroborate [Rh(COD) 2 ] BF 4 (2.1mg, 0.005mmol), the system passed through the vacuum line, replaced with nitrogen three times, added freshly steamed degassed toluene (2mL), the solution was stirred at room temperature for 1 hour, and the solvent was removed under reduced pressure to obtain a brown solid, which was vacuum pumped for 2 After 1 hour, add 2mL of toluene solvent, and add this solution into BF containing E-citral (761mg, 5mmol, E / Z=99 / 1, chiral rhodium complex [Rh(R-L1b)(COD)] 4 The molar ratio with citral is 1 / 1000) and potassium iodide (42mg, 0.25mmol) in a vial, put into an autoclave, and after 6 times of hydrogen replacement, make the initial hydrogen pressure 35bar, and stir and react at 35°C for 10 hours. Cool, release gas carefully, open the autoclave, take out the vial, drain the solvent, NM...

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Abstract

The invention relates to a method for preparing chiral citronellal through citral catalytic asymmetric hydrogenation in the technical field of chemical engineering. Under the effect of additives such as sodium iodide, tetraoctyl ammonium bromide and phenyltriethylammonium chloride, E-type and/or Z-type citral is catalyzed by chiral rhodium complex and asymmetrically hydrogenated into R or S chiral citronellal. In addition, E-type or Z-type citral can be catalyzed into chiral citronellal of the same required structure by changing chirality of chiral catalysts. Thus, citral of all structures can be completely converted into chiral rhodium of one required structure. The reaction method is mild in condition, easy and convenient to operate, capable of achieving good reaction yield and reaction efficiency and good in application effect.

Description

technical field [0001] The invention relates to a method for preparing chiral citronellal in the technical field of chemical industry, in particular to a method for synthesizing chiral citronellal by asymmetric rhodium-catalyzed hydrogenation of citral, belonging to the field of flavors and fragrances. Background technique [0002] Citronellal is an important fragrance ingredient and the precursor of many flavors and fragrances, such as hydroxycitronellal and menthol, which can be used to synthesize other fragrances. Especially the most important intermediate in the synthesis of menthol. At the same time, it is also widely used in the flavoring and preparation of beverages, candies, and food. Therefore, the demand for citronellal, especially chiral citronellal, is constantly increasing. Therefore, its synthesis method has always been valued by researchers and companies. At present, there are a few patents on the synthesis of chiral citronellal, and its synthesis methods a...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C47/21C07C45/62B01J31/22
CPCB01J31/2295B01J2231/645C07C45/62C07C47/21
Inventor 张万斌张振锋陈建中董菁鲍元野张永振黎源
Owner WANHUA CHEM GRP CO LTD
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