Tetraphenylmethane is an organic compound consisting of a methane core with four phenyl

substituent A substituent is one or a group of atoms that replaces (one or more) atoms, thereby becoming a moiety in the resultant (new) molecule. (In organic chemistry and biochemistry, the terms ''substituent'' and ''functional group'', as well as ''side ...

s. It was first synthesized by Moses Gomberg in 1898.

Synthesis

Gomberg's classical

organic synthesis Organic synthesis is a special branch of chemical synthesis and is concerned with the intentional construction of organic compounds. Organic molecules are often more complex than inorganic compounds, and their synthesis has developed into one o ...

shown below starts by reacting triphenylmethyl bromide 1 with phenylhydrazine 2 to the

hydrazine Hydrazine is an inorganic compound with the chemical formula . It is a simple pnictogen hydride, and is a colourless flammable liquid with an ammonia-like odour. Hydrazine is highly toxic unless handled in solution as, for example, hydrazine ...

3. Oxidation with nitrous acid then produces the azo compound 4 from which on heating above the melting point, nitrogen gas evolves with formation of tetraphenylmethane 5.{{cite journal , title = On tetraphenylmethane , first= M. , last=Gomberg , journal = J. Am. Chem. Soc. , year = 1898 , volume = 20 , issue = 10 , pages = 773–780 , doi= 10.1021/ja02072a009, url= https://zenodo.org/record/1428930 : Gomberg was able to distinguish this compound from triphenylmethane ( elemental analysis was not an option given the small differences in the hydrogen fractions of 6.29% and 6.60%) by nitration of 5 with nitric acid to 6. A strong base would be able to abstract the methine proton of the nitrated triphenylmethyl compound if present, forming a strongly colored compound. He obtained further evidence for the formation of tetraphenylmethane by reducing the nitro groups to amino groups with zinc dust in

acetic acid Acetic acid , systematically named ethanoic acid , is an acidic, colourless liquid and organic compound with the chemical formula (also written as , , or ). Vinegar is at least 4% acetic acid by volume, making acetic acid the main component ...

to the leuco dye 7, which on exposure to hydrochloric acid eliminates aniline to the known compound pararosaniline 8. Gomberg's success in synthesizing tetraphenylmethane set him on the attempt to prepare the next homologue hexaphenylethane, which led him to the discovery of the triphenylmethyl radical.

References

Aromatic hydrocarbons Phenyl compounds

Synthesis

See also

References