- Diphenylmethane
- Methylene diphenyl diisocyanate
- Thorpe–Ingold effect
- Gorilla Glue
- Benzhydryl compounds
- Fixative (perfumery)
- ATC code N05
- Bisphenol
- Benzophenone
- Triphenylmethane
diphenylmethane
Diphenylmethane GudangMovies21 Rebahinxxi LK21
Diphenylmethane is an organic compound with the formula (C6H5)2CH2 (often abbreviated CH2Ph2). The compound consists of methane wherein two hydrogen atoms are replaced by two phenyl groups. It is a white solid.
Diphenylmethane is a common skeleton in organic chemistry. The diphenylmethyl group is also known as benzhydryl.
Synthesis
It is prepared by the Friedel–Crafts alkylation of benzyl chloride with benzene in the presence of a Lewis acid such as aluminium chloride:
C6H5CH2Cl + C6H6 → (C6H5)2CH2 + HCl
Reactivity of the C-H bond
The methylene group in diphenylmethane is mildly acidic with a pKa of 32.2, and so can be deprotonated with sodium amide.
(C6H5)2CH2 + NaNH2− → (C6H5)2CHNa + NH3
The resulting carbanion can be alkylated. For example, treatment with n-bromobutane produces 1,1-diphenylpentane in 92% yield.
(C6H5)2CH− + CH3CH2CH2CH2Br → (C6H5)2CHCH2CH2CH2CH3 + Br−
Alkylation of various benzhydryl compounds has been demonstrated using the corresponding alkyl halides, both primary (benzyl chloride, β-phenylethyl chloride, and n-octyl bromide) and secondary (benzhydryl chloride, α-phenylethyl chloride, and isopropyl chloride), in yields between 86 and 99%.
The acidity of the methylene group in diphenylmethane is due to the weakness of the (C6H5)2CH–H bond, which has a bond dissociation energy of 82 kcal mol−1 (340 kJ mol−1). This is well below the published bond dissociation energies for comparable C–H bonds in propane, where BDE((CH3)2CH–H)=98.6 kcal mol−1, and toluene, where BDE(C6H5CH2–H)=89.7 kcal mol−1.
See also
Benzhydryl compounds
Toluene, a.k.a. methylbenzene, phenylmethane
Triphenylmethane
Tetraphenylmethane