Réaction #56554

Équation de réaction

Lithium Borohydride

retinal

hydrochloric acid

→

beta-carotene

Rendement 60.0%

Solvants

tetrahydrofuran

Conditions de réaction

Traitement

1. 1
   AutreA solution was prepared
2. 2
   Températurethe reaction was refluxed for four hours
3. 3
   Extractionwas extracted several times with ether
4. 4
   Lavagewashed with saturated aqueous sodium chloride solution
5. 5
   Séchagedried over magnesium sulfate
6. 6
   Concentrationconcentrated by solvent removal at the rotary evaporator
7. 7
   AutreThe residue was further purified by chromatography on silica gel
8. 8
   LavageElution with hexane

Mode opératoire

A solution was prepared by dissolving titanium tetrachloride (1.10 ml, 10.0 mmol) in 25 ml dry tetrahydrofuran under an inert atmosphere. Lithium Borohydride (110 mg, 5.0 mmol) was added, and the resulting solution was stirred at 50° for two hours. A solution of retinal (1.42 gm, 5.0 mmol) 5 ml dry tetrahydrofuran was added, and the reaction was refluxed for four hours. After this, the solution was poured into 50 ml 2 N aqueous hydrochloric acid, and was extracted several times 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 further purified by chromatography on silica gel. Elution with hexane gave 0.8 gm (60%) beta-carotene, identified by comparison with an authentic sample; mp 180°-182°.

Source