Hydrochloric Acid → Beta-Carotene

HRID 28270

Reaction equation

HRID 28270 reaction equation
[CH3:1][C:2]1[CH2:7][CH2:6][CH2:5][C:4]([CH3:9])([CH3:8])[C:3]=1/[CH:10]=[CH:11]/[C:12](/[CH3:21])=[CH:13]/[CH:14]=[CH:15]/[C:16](/[CH3:20])=[CH:17]/[CH:18]=O.Cl>O1CCCC1>[CH3:1][C:2]1[CH2:7][CH2:6][CH2:5][C:4]([CH3:9])([CH3:8])[C:3]=1/[CH:10]=[CH:11]/[C:12](/[CH3:21])=[CH:13]/[CH:14]=[CH:15]/[C:16](/[CH3:20])=[CH:17]/[CH:18]=[CH:18]/[CH:17]=[C:16](\[CH3:20])/[CH:15]=[CH:14]/[CH:13]=[C:12](\[CH3:21])/[CH:11]=[CH:10]/[C:3]1[C:4]([CH3:9])([CH3:8])[CH2:5][CH2:6][CH2:7][C:2]=1[CH3:1]

Participants

4

Reactant 2

HCID 313Hydrochloric AcidHCID 638015Retinal

Product 1

HCID 5280489Beta-CaroteneYield 75%

Reagents, catalysts & solvents 1

HCID 8028TetrahydrofuranSolvent

Procedure

A solution was prepared by dissolving titanium tetrachloride (1.10 ml, 10.0 mmol) in 25 ml dry tetrahydrofuran under an inert atmosphere (nitrogen or argon). Lithium Aluminum hydride (190 mg, 50. mmol.) was carefully added, and the resulting solution was stirred for two hours at room temperature to form the active Ti(II) reagent. A solution of retinal (1.42 gm, 5.0 mmol) in 5 ml dry tetrahydrofuran was then added, and the reaction was stirred overnight at room temperature. 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 1.0 gm (75% yield) beta-carotene, identified by thin layer chromatographic comparison with an authentic sample, and by melting point data: mp. 180°-182°.

Workup

  1. extractionwas extracted several times with ether
  2. washwashed with saturated aqueous sodium chloride solution
  3. dry with materialdried over magnesium sulfate
  4. concentrationconcentrated by solvent removal at the rotary evaporator
  5. customThe residue was further purified by chromatography on silica gel
  6. washElution with hexane

Sources & evidence

ORD record
ord-72f175a46d994f108d393ba531d9d6a5
Source dataset
uspto-grants-1980_09
Patent number
US04225734

Linked notes

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