Reacción #56547

Ecuación de reacción

retinal

hydrochloric acid

→

beta-carotene

Rendimiento 85.0%

Disolventes

tetrahydrofuran

Condiciones de reacción

Tratamiento posterior

1. 1
   ExtracciónThe solution was extracted several times with ether
2. 2
   Lavadowashed with saturated aqueous sodium chloride solution
3. 3
   Secadodried over magnesium sulfate
4. 4
   Concentraciónconcentrated by solvent removal at the rotary evaporator
5. 5
   OtroThe residue was purified by chromatography on silica gel
6. 6
   LavadoElution with hexane

Procedimiento

A slurry of titanium trichloride (1.54 gm, 10.0 mmol) in 30 ml dry tetrahydrofuran was prepared under an inert atmosphere (nitrogen or argon), and powdered lithium aluminum hydride (190 mg. 5.0 mmol) was cautiously added. The resulting solution was stirred for two hours at room temperature to form the Ti(II) reagent, and a solution of retinal (1.42 gm, 5.0 mmol) in 5 ml dry tetrahydrofuran was added. The solution was stirred a further fifteen hours at room temperature, and then poured into 50 ml 2 N aqueous hydrochloric acid. The solution was extracted several times with ether, and 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 purified by chromatography on silica gel. Elution with hexane gave 1.14 gm (85% yield) beta-carotene which was identified by thin-layer chromatographic comparison with an authentic sample, by its characteristic ultraviolet spectrum, and by its melting point: mp 180°-182°.

Fuente