反応 #969871

反応方程式

2,5,6,6-Tetramethyl-cyclohexene carbaldehyde

cyclohexane

p-toluene sulfonic acid

→

2-(2,5,6,6-tetramethyl-cyclohexenyl)-1,3-dioxolane

溶媒

water

ethylene glycol

ethylene glycol

反応条件

後処理

1. 1
   その他equipped with a heating circulator, temperature probe, mechanical stirring device
2. 2
   温度The biphasic mixture was heated
3. 3
   温度to reflux
4. 4
   温度After 8 hours reflux the reaction
5. 5
   濃縮was concentrated under vacuum in order
6. 6
   その他to remove cyclohexane
7. 7
   その他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
8. 8
   workup.DISTILLATIONFlash distillation

実験手順

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.

出典