Diphenylmethanol

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Diphenylmethanol
Names
IUPAC name
Diphenylmethanol
Systematic IUPAC name
Diphenylmethanol
Other names
1,1-Diphenylmethanol
Benzhydrol
Diphenylcarbinol
Hydroxydiphenylmethane
Properties
C13H12O
(C6H5)2CHOH
Molar mass 184.238 g/mol
Appearance White solid
Odor Odorless
Density 1.103 g/cm3
Melting point 65–67 °C (149–153 °F; 338–340 K)
Boiling point 297–298 °C (567–568 °F; 570–571 K)
0.05 g/100 ml (20 °C)
Solubility Soluble in acetonitrile, chloroform, diethyl ether, ethanol, methanol
Solubility in ethanol 35 g/100 ml[1]
Vapor pressure 2.73·10-5 mmHg at 20 °C
Thermochemistry
-105.34 kJ/mol
Hazards
Safety data sheet Sigma-Aldrich
Flash point 160 °C (320 °F; 433 K)
Lethal dose or concentration (LD, LC):
5,000 mg/kg (rat, oral)
Related compounds
Related compounds
Benzyl alcohol
Triphenylmethanol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Diphenylmethanol or benzhydrol is the organic compound with the formula C13H12O.

Properties

Chemical

Diphenylmethanol can be oxidized to benzophenone.

Physical

Diphenylmethanol is a white solid, insoluble in water, but soluble in organic solvents.

Chromatographic

It should be noted that when assessing the purity of benzophenone by TLC, that benzophenone (a likely impurity) is considerably more UV active at 254 nm than diphenylmethanol, and thus make a trace contamination seem more significant that it really is.[2]

Useable TLC systems are (as measured on Merck silica gel 60 F254, visualized with 254 nm UV):

Eluent: hexane/ethyl acetate, 9/1, v/v

Rf (diphenylmethanol) = 0.26 - 0.30
Rf (benzophenone) = 0.51

Eluent: hexane/ethyl acetate, 1/1, v/v

Rf (diphenylmethanol) = 0.72

Availability

Diphenylmethanol is sold by chemical suppliers.

Preparation

Diphenylmethanol may be prepared by a Grignard reaction between phenylmagnesium bromide (prepared from benzyl bromide and magnesium) and benzaldehyde. The resulting benhydrol is obtained by adding cold water/crushed ice to the reaction product.[3]

C6H5MgBr + C6H5CHO → (C6H6)2CH-OMgBr
(C6H6)2CH-OMgBr + H2O → (C6H6)2CH-OH + Mg(OH)Br

Reducing benzophenone is another route.

(C6H6)2C=O + 2 [H] → (C6H6)2CH-OH

Reducing agents used for this reaction are:

Interestingly enough, according to one source, benzhydrol can also be obtained by reducing benzophenone using only sodium hydroxide in isopropanol. The reaction takes place under reflux, for 27 h, and the yield of this route is claimed to be 90%.[6]

Can also be prepared by hydrolyzing diphenhydramine.

Projects

  • Synthesis of Modafinil/Armodafinil, Adrafinil
  • Synthesis of Diphenhydramine

Handling

Safety

Diphenylmethanol is an irritant to the eyes, skin and respiratory system.

Storage

In closed bottles.

Disposal

No special disposal is required as it's not very toxic.

References

  1. Cohen; Recueil des Travaux Chimiques des Pays-Bas; vol. 38; (1919); p. 88
  2. 2.0 2.1 R. Ramakrishna, SyntheticPage 2012, 539, doi:10.1039/SP539
  3. Making a Secondary Alcohol Called Benzhydrol
  4. Synthesis of Benzhydrol
  5. http://www.orgsyn.org/demo.aspx?prep=cv1p0090
  6. Daniel R. Zuidema, Katherine J. Wert, Sarah L. Williams, Samuel T. Chill, Kimberly L. Holte, Nathanael K. Kokes, Novel Method of Reducing Ketones Using Sodium Hydroxide in Isopropanol, Synthetic Communications, Volume 40, 2010 - Issue 8, p. 1187-1191

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