反応 #56550

反応方程式

retinal

hydrochloric acid

→

beta-carotene

収率 65.0%

溶媒

tetrahydrofuran

反応条件

後処理

1. 1
   温度After refluxing for a further two hours
2. 2
   抽出extracted with ether
3. 3
   洗浄washed with saturated aqueous sodium chloride solution
4. 4
   乾燥dried over magnesium sulfate
5. 5
   濃縮concentrated by solvent removal at the rotary evaporator
6. 6
   洗浄Elution with hexane

実験手順

Zinc dust (654 mg, 10.0 mmol) was slurred in 20 ml dry tetrahydrofuran under an inert atmosphere (nitrogen or argon), and a solution of titanium tetrachloride (0.55 ml, 5.0 mmol) in 3 ml dry benzene was rapidly added. The resulting solution was refluxed overnight to form active Ti(II) reagent, and a solution of retinal (710 mg, 2.5 mmol) in 5 ml dry tetrahydrofuran was added. After refluxing for a further two hours, the solution was cooled to room temperature, poured into 50 ml 2 N aqueous hydrochloric acid, and extracted with ether. The ether extracts were combined, washed with saturated aqueous sodium chloride solution, dried over magnesium sulfate, and concentrated by solvent removal at the rotary evaporator. The residue was purfied by chromatography on a silica gel column. Elution with hexane gave 430 mg (65% yield) of beta-carotene which crystallized in the flask. The beta-carotene was identified by tlc comparison with an authentic sample, and by melting point comparison of a recrystallized sample; mp 180°-182°.

出典