Benzhydrol

Chemical Properties

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.

Uses

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).

Uses

Anchoring of carboxylic acids and alcohols

Definition

ChEBI: Diphenylmethanol is a secondary alcohol that is diphenylmethane which carries a hydroxy group at position 1. It has a role as a rat metabolite, a bacterial xenobiotic metabolite, a human xenobiotic metabolite and a human urinary metabolite. It is a secondary alcohol and a member of benzyl alcohols. It derives from a hydride of a diphenylmethane.

Preparation

By reduction of Benzophenone, e.g. with zinc in aqueous alkali.

Reactions

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.

Synthesis Reference(s)

Canadian Journal of Chemistry, 50, p. 3058, 1972 DOI: 10.1139/v72-485
Journal of the American Chemical Society, 55, p. 391, 1933 DOI: 10.1021/ja01328a057
Tetrahedron Letters, 29, p. 139, 1988 DOI: 10.1016/S0040-4039(00)80036-2

General Description

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

Purification Methods

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.]

Toxics Screening Level

The ITSL for Benzhydrol has been set at 16 μg/m3 based on annual average time.