Method for preparing R-citronellal

A technology of citronellal and transition metals, applied in the field of R-citronellal preparation, can solve the problems of complex process operation, complex process, harsh recovery and application conditions, etc.

Active Publication Date: 2020-10-20
WANHUA CHEM GRP CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The use of this catalyst can effectively improve product chemistry and stereoselectivity, but there are disadvantages of low hydrogenation efficiency, especially under the condition of high substrate/catalyst, the conversion frequency of the catalyst is significantly reduced, resulting in the need for multiple recycling of the catalyst and complicated process operations , and the catalyst life is short, prone to noble metal coupling deactivation and other disadvantages
[0007] In summary, ...

Method used

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  • Method for preparing R-citronellal
  • Method for preparing R-citronellal
  • Method for preparing R-citronellal

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0064] Add 8.9 grams of montmorillonite (montmorillonite K10) and 1 gram of nanosilver (20- 40 nanometers), after stirring at 30° C. for 1 hour, the montmorillonite and nano-silver were removed by filtration through a closed filter.

[0065] 7.5mg Rh(CO) 2 acac (0.029mmol) and 18.6mg (S,S)-chiraphos (0.436mmol) were dissolved in the above 8836g geranial (the molar ratio of geranial / neral double bond isomer=99:1); The molar calculation of rhodium atom in, substrate / catalyst molar ratio=2000000), join in the reactor, by injecting hydrogen, reaction pressure is adjusted to 80 bar (reaction pressure, bar), be warming up to 90 ℃ (reaction temperature) After reacting for 8 hours (reaction time), the conversion rate and optical purity measured by gas chromatography are listed in Table 1.

Embodiment 2-9

[0067] Examples 2-9 were carried out with reference to Example 1, except for the selection of aluminosilicate, nano-silver, reaction temperature, reaction pressure and reaction time, see Table 1 for details.

[0068] Table 1

[0069]

Embodiment 10

[0071] Add 1 gram of montmorillonite K10 to 8836g of neral aldehyde (the molar ratio of neral / geranial double bond isomers=99:1) under nitrogen atmosphere, stir at 10°C for 20 hours, pass The airtight filter removes the montmorillonite by filtration.

[0072] 7.5mg Rh(CO) 2 acac (0.029mmol) and 13mg (R, R)-chiraphos (0.030mmol) were dissolved in the above 8836g neral (the molar ratio of neral / geranial double bond isomer=99:1; Rhodium atom meter, substrate / catalyst molar ratio=2000000), was added in the reaction kettle, the reaction pressure was adjusted to 80 bar by injecting hydrogen, after the temperature was raised to 90°C for 8 hours, the conversion rate was measured by gas chromatography to be 53 %, the cumulative conversion number is 1,056,000, and the optical purity is 91%.

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Abstract

The invention provides a method for preparing R-citronellal. The catalytic activity and stability of a catalyst can be remarkably improved based on the method provided by the invention, so a higher cumulative conversion number is realized. According to the method for preparing R-citronellal provided by the invention, a reaction substrate is subjected to an asymmetric hydrogenation reaction in thepresence of a transition metal catalyst to generate R-citronellal; the reaction substrate is selected from neryl aldehyde and/or geranial, and the transition metal catalyst is obtained through a reaction of a transition metal compound capable of being dissolved in a reaction system and an optically active ligand containing two phosphorus atoms; and before the reaction substrate is put into the reaction system of the asymmetric hydrogenation reaction, the reaction substrate is pretreated by using aluminosilicate and/or nano-silver, and filtering is conduced to remove the aluminosilicate and/ornano-silver after pretreatment.

Description

technical field [0001] The invention relates to the technical field of R-citronellal preparation, in particular to a method for preparing R-citronellal by asymmetrically hydrogenating neral and / or geranial. Background technique [0002] Citronellal is a compound with a chiral center, because R-citronellal is an important intermediate for the synthesis of L-menthol, so its preparation method, especially low-cost, large-scale industrial preparation method has the advantages of Significance. [0003] Adv.Synth.Catal., 2003, 345 (1): 15-32 has reported that Takasago Company takes myrcene as raw material, obtains the method for R-citronellal through three-step reaction, and its core technology is the non-toxicity of allylamine Symmetrical isomerization, this process step is long, needs to use a large amount of lithium reagents. [0004] EP 0000315 reports a process for the preparation of optically active R-citronellal by hydrogenating geranial or neral in the presence of a cata...

Claims

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Application Information

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IPC IPC(8): C07C45/62C07C45/78C07C45/79C07C45/85C07C47/21C07B53/00
CPCC07C45/62C07C45/78C07C45/79C07C45/85C07B53/00B01J31/2409B01J31/2414B01J2231/645B01J2531/822C07B2200/07C07C47/21
Inventor 董菁于磊张永振黎源
Owner WANHUA CHEM GRP CO LTD
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