p-Toluenesulfonic acid → HCID 66770509, compound

HRID 882689Notes

Reaction equation

HRID 882689 reaction equation
[CH3:1][C:2]1[CH2:7][CH2:6][CH:5]([CH3:8])[C:4]([CH3:10])([CH3:9])[C:3]=1[CH:11]=[O:12].[CH2:13]1[CH2:18]CCCC1.C1(C)C=CC(S(O)(=O)=[O:26])=CC=1>O.C1(C)C=CC(S(O)(=O)=O)=CC=1.C(O)CO.O>[CH3:1][C:2]1[CH2:7][CH2:6][CH:5]([CH3:8])[C:4]([CH3:10])([CH3:9])[C:3]=1[CH:11]1[O:26][CH2:13][CH2:18][O:12]1

Participants

7

Reactant 3

HCID 6101p-Toluenesulfonic acidHCID 8078CyclohexaneHCID 144329422,5,6,6-Tetramethylcyclohex-1-ene-1-carbaldehyde

Product 1

HCID 66770509HCID 66770509, compound

Reagents, catalysts & solvents 3

HCID 521998p-Toluenesulfonic acid monohydrateCatalystHCID 174Ethylene GlycolSolvent2×HCID 962WaterSolvent

Procedure

2,5,6,6-Tetramethyl-cyclohexene carbaldehyde (64/7/29 trans 2-ene/cis 2-ene/1-ene isomers mixture) (1660 g, 10 mol., 1 eq.), ethylene glycol (1240 g, 20 mol., 2 eq.), cyclohexane (1660 g) and p-toluene sulfonic acid monohydrate (7.6 g, 0.04 mol., 0.004 eq.) were loaded altogether in a 10 liter schmizo type reactor equipped with a heating circulator, temperature probe, mechanical stirring device and a Dean-stark apparatus. The biphasic mixture was heated to reflux under vigorous stirring with azeotropic water removal from reaction mixture. After 8 hours reflux the reaction was then cooled down to room temperature. After decantation of the bottom phase containing excess ethylene glycol and p-toluene sulfonic acid the upper phase was concentrated under vacuum in order to remove cyclohexane and crude 2-(2,5,6,6-tetramethyl-cyclohexenyl)-1,3-dioxolane was obtained in 80% GC purity as a 80/7/13 trans 2-enyl/cis 2-en/1-enyl isomers mixture. Flash distillation afforded 1940 g of 2-(2,5,6,6-tetramethyl-cyclohexenyl)-1,3-dioxolane along with 60 g of residual heavy by-products formed during the reaction.

Workup

  1. customequipped with a heating circulator, temperature probe, mechanical stirring device
  2. temperatureThe biphasic mixture was heated
  3. temperatureto reflux
  4. temperatureAfter 8 hours reflux the reaction
  5. concentrationwas concentrated under vacuum in order
  6. customto remove cyclohexane
  7. customcrude 2-(2,5,6,6-tetramethyl-cyclohexenyl)-1,3-dioxolane was obtained in 80% GC purity as a 80/7/13 trans 2-enyl/cis 2-en/1-enyl isomers mixture
  8. distillationFlash distillation

Sources & evidence

ORD record
ord-1d9cbc1e1d9147ca9ea21a20f076b4ed
Source dataset
uspto-grants-2012_08
Patent number
US08236749B2

Reaction notes

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