Reaktion #56554

Reaktionsgleichung

Lithium Borohydride

retinal

hydrochloric acid

→

beta-carotene

Ausbeute 60.0%

Lösungsmittel

tetrahydrofuran

Reaktionsbedingungen

Aufarbeitung

1. 1
   SonstigeA solution was prepared
2. 2
   Temperaturthe reaction was refluxed for four hours
3. 3
   Extraktionwas extracted several times with ether
4. 4
   Waschenwashed with saturated aqueous sodium chloride solution
5. 5
   Trocknendried over magnesium sulfate
6. 6
   Einengenconcentrated by solvent removal at the rotary evaporator
7. 7
   SonstigeThe residue was further purified by chromatography on silica gel
8. 8
   WaschenElution with hexane

Vorschrift

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°.

Quelle