Methacrolein → 1,2,4-Trimethylcyclohex-3-ene-1-carbaldehyde

HRID 411117Notes

Reaction equation

HRID 411117 reaction equation
[CH3:1][C:2]([CH:4]=[CH:5]C)=[CH2:3].[O:7]=[CH:8][C:9](=[CH2:11])[CH3:10].[CH:12]([Mg]Br)(C)C.[Cl-].[NH4+]>C(OCC)C>[CH3:11][C:9]1([CH:8]=[O:7])[CH2:5][CH2:4][C:2]([CH3:3])=[CH:1][CH:10]1[CH3:12]

Participants

6

Reactant 4

HCID 6562MethacroleinHCID 142381,3-Pentadiene, 2-methyl-HCID 25517Ammonium ChlorideHCID 178418365HCID 178418365, compound

Product 1

HCID 1729121,2,4-Trimethylcyclohex-3-ene-1-carbaldehyde

Reagents, catalysts & solvents 1

HCID 3283Diethyl EtherSolvent

Procedure

1,2,4-trimethyl-3-cyclohexene-1-carboxaldehyde was prepared by a Diels-Alder reaction between 2-methyl1,3-pentadiene and methacrolein (prepared by Mannich-chemistry). To this aldehyde (15 g, 0.1M) in 100 ml diethyl ether, cooled in an ice bath, was added via a syringe isopropylmagnesium bromide (60 ml, 2.0M solution in diethyl ether). The reaction mixture was stirred for 2 hours and allowed to warm to ambient temperature then poured slowly into a dilute aqueous solution of ammonium chloride. The organic phase was separated and the aqueous phase extracted with more diethyl ether (50 ml). The organic extracts were combined, washed with water, dried with magnesium sulphate, filtered and solvent removed via rotary evaporation (rotavap). The crude was analysed by GC then GCMS. 4 product peaks of relative peak area (hereinafter to as “rpa”) 77.6%, 8.5%, 5.2% and 4.1% were shown to have MWs 154, 154, 196, 196, respectively. Hence the 2 major products were not the required isopropyl additions, but were comparable to the starting aldehyde being reduced to the corresponding alcohol, having the following structure:

Workup

  1. customThe organic phase was separated
  2. extractionthe aqueous phase extracted with more diethyl ether (50 ml)
  3. washwashed with water
  4. dry with materialdried with magnesium sulphate
  5. filtrationfiltered
  6. customsolvent removed via rotary evaporation (rotavap)

Sources & evidence

ORD record
ord-7132e5e4c3604c4aaab758e0afe4473c
Source dataset
uspto-grants-2003_05
Patent number
US06559118B1

Reaction notes

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