Benzil

• Dibenzoyl
• Diphenylglyoxal
• Diphenylethandion
• 1,2- diphenylethane -1 ,2- dione

Yellow crystals with a characteristic odor

Fixed

1.23 g · cm -3 ( 25 ° C)

95 ° C.

Decomposition from 346 ° C

Poorly in water ( > 0.5 g · l-1 at 20 ° C)

Attention

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Benzil and a diketone having the formula C6H5 -CO -CO- C6H5.

Production and representation

Benzil may be obtained by benzoin condensation followed by oxidation of benzaldehyde of benzoin by copper sulfate.

Properties

Physical Properties

Benzil is a crystalline solid, which can occur in two polymorphic crystal forms. Below -189 ° C, the crystal form II exists, above this temperature the crystal form I. The transition enthalpy of the solid phase transition is 0.0441 kJ · mol -1. Crystal Form I melts at 95 ° C with a melting enthalpy of 23.556 kJ · mol -1. Boiling the compound under a reduced pressure of 16 mbar at 188 ° C. The vapor pressure function is given by Antoine corresponding log10 (P) = A- ( B / ( T C )) ( P in bar, T in K) with A = 4.79729, B = 2780.085 and C = -39 436 in the temperature range from 401.6 to 620 K

Chemical Properties

Benzil is the starting material for the benzylic acid rearrangement.

Use

Benzil is used as an intermediate in organic syntheses and as a photoinitiator for certain polymer reactions.

Safety

Benzil irritates the eyes, the skin and the respiratory tract which can lead to ignition. The fumes are highly toxic and should not be inhaled.

Itemization

• Irritant
• Ketone