Technical notes. 2230. Synthesis and purification of alkyldiphenylmethane hydrocarbons; 1, 2-methyldiphenylmethane, 3-methyldiphenylmethane, 2-ethyldiphenylmethane. 3-ethyldiphenylmethane, and 4-isopropyldiphenylmethane [with list of references]; by John H. Lamneck, jr., and Paul H. Wise.