Бензгидрола

Химические свойства

off-white powder or White or colorless crystals. M.P. 69℃. B.p. 281℃. Practically insoluble in water, soluble in alcohol, miscible with oils. The crystals have a very faint musty-rosy odor, somewhat similar to that of Benzophenonc and Trichloromethyl phenyl carbinyl acetate.

Использование

1. Benzhydrols are industrially important compounds. On oxidation Benzhydrols yields Benzophenone, which are useful synthones for fullerenes, bioactive oxygen heterocycles, dyes and medicines. Various Cr (VI) and other oxidizing agents are used for oxidizing benzhydrol.
2. Benzhydrol is widely used as intermediates in pharmaceuticals (including antihistamines), agrochemicals, perfumes and other organic compounds. It is used as a fixative in the perfume industry. It is involved in polymerization reaction as a terminating group. It is used as precursor to prepare modafinil, benztropine and diphehydramine.
3. Intermediate in the preparation of Modafinil (M482500).

Реакции

Benzhydrol is oxidized to benzophenone, by sodium hypochlorite (commonly known as bleach) in the presence of a phase-transfer catalyst.
Synthesis: In a 20-mL green capped vial, place 1.5 mL of ethyl acetate, 100 mg (0.54 mmol) of benzhydrol and a few drops of methyltricaprylammonium chloride solution (Stark's catalyst or tricaprylmethylammonium chloride). Add a half-inch magnetic stirring bar, and stir until all reagents are dissolved. Cool the solution in an ice bath and add 2 mL of 5% NaOCl (aq) (bleach) dropwise using a 2.5- mL syringe. After the addition of the hypochlorite is complete, allow the reaction to stir for five minutes in the ice-water bath and then stir for a period of one hour at room temperature.

Reduction of benzophenone to benzhydrol.
4MPDC (4-Methyl pyridinium di chromate) is used as oxidizing agent to oxidize benzhydrol. PDC is a mild and selective oxidizing agent and is soluble in water and many organic solvents. Therefore, advantage over inorganic dichromate.

Общее описание

Pharmaceutical secondary standards for application in quality control provide pharma laboratories and manufacturers with a convenient and cost-effective alternative to the preparation of in-house working standards

Методы очистки

Crystallise benzhydrol from hot H2O or pet ether (b 60-70o), pet ether containing a little *benzene, from CCl4, or EtOH (1mL/g). An additional purification step includes passage of a *benzene solution through an activated alumina column. It sublimes in a vacuum. Also recrystallise it three times from MeOH/H2O [Naguib J Am Chem Soc 108 128 1986]. [Beilstein 6 IV 4648.]