Microwave assisted rapid and economical process for the preparation of substituted phenylaldehydes from trans and cis-phenylpropenes: a commercial utilisation of toxic cis-isomer
AssigneeCouncil of Scientific and Industrial Research
InventorsArun Kumar Sinha, Bhupendra Prasad Joshi, Ruchi Dogra
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Abstract
The present invention provides microwave assisted rapid and economical process for the preparation of substituted phenylaldehydes from trans and cis-phenylpropene, a commercial utilization of toxic cis-isomer of the general formula (I) 1 using meta-periodate and osmium tetraoxide (catalytic amount) as an efficient oxidizing agent in the presence of catalyst namely amberlite IRA-410 and quaternary ammonium salt.
Claims17
Microwave assisted rapid and economical process for the preparation of substituted phenylaldehydes from trans and toxic cis-phenylpropenes, a commercial utilization of toxic cis-isomer of the general formula (I) as given below:
- 5
- wherein R1 is —CHO,
- R2, R3, R4, R5, R6 are independently selected from
- i) a hydrogen atom;
- ii) an alkoxy group at least two of R2, R3, R4, R5, R6 being hydrogen atom;
- or an alkoxy group but one of R2, R3, R4, R5, R6 being methylenedioxy group in combination with either hydroxyl group, an alkoxy group, an alkyl group having atleast one carbon atom, an aryl group and a hydrogen atom or an alkoxy group but one of R2, R3, R4, R5, R6 being hydroxyl group in combination with either methylenedioxy group, a hydroxyl group, an alkoxy group, an alkyl group having atleast one carbon atom, an aryl group (—C6H5)or a hydrogen atom;
- iii) a methylenedioxy group at least three of R2, R3, R4, R5, R6 being in combination with either an alkoxy group, a hydroxy group, an alkyl group having atleast one carbon atom, an aryl group or a hydrogen atom;
- iv) a hydroxyl group at least one of R2, R3, R4, R5, R6 being a hydrogen atom in combination with either an alkoxy group, a hydroxyl group, a methylenedioxy group, an alkyl group having atleast one carbon atom, an aryl group or a hydrogen atom;
- v) a protected hydroxyl group such as acetyl, benzyl, etc at least one of R2, R3, R4, R5, R6 being a hydrogen atom in combination with either an alkoxy, a hydroxyl group, a methylenedioxy group, an alkyl group having one or more carbon atoms, an aryl group or a hydrogen atom;
- said substituted phenylaldehydes being from corresponding (R2—R3—R4—R5—R6)phenylpropene derivatives, said process comprising oxidizing phenylpropene derivatives in presence of an oxidizing agent and optionally a co catalyst in a solvent at a mole ratio of 1:1 to 1:12 for a period ranging from 20 seconds to 20 minutes under microwave radiation, removing the solvent under reduced pressure and isolating the product in a conventional manner to obtain a yield between 71 to 82% of substituted phenylaldehydes.
A process as claimed in 1 wherein, above process is capable of preparing phenylaldehyde derivatives on commercial scale.
A process as claimed in 1 wherein, a simple and cheaper starting material in which what ever percentage of cis (toxic) and trans-isomer (preferred) exists in crude essential oil or formed during alkaline isomerisation of γ-phenylpropenes (such as methylchavicol, safrole, methyl eugenol etc) are oxidized into high valued phenylaldehydes, otherwise higher than the allowed percentage of cis-isomer formed along with the trans-isomer is not allowed for commercial use in perfumery, flavour and pharmaceutics.
A process as claimed in 1 wherein, in the above process for the preparation of some new phenylaldehydes, which are useful as a simple starting material for synthesis of corresponding acids, esters, amides, alcohol, and β-unsaturated aldehyde and are also useful for the dyes, alkaloids, agrochemicals etc.
Dependencies are inferred from the claim text.