A novel liquid/solid two-phase reaction of a,a,a-trichlorotoluene (PhCCl3) and acetonitrile (AN) has been discovered that produces a carbon-based polymer with diamondlike structure at the atomic level. The solid phase is potassium hydroxide particles, and the liquid phase is a tetrahydrofuran solution of PhCCl3 and AN containing a certain amount of tetrabutylammonium bromide as a phase-transfer catalyst. The structure of the carbon-based polymer has been characterized by elemental analysis, Fourier transform infrared spectroscopy, and H-1- and C-13-NMR spectroscopy. The pyrolysis of the carbon-based polymer at 800degreesC under a nitrogen atmosphere leads to the formation of a diamondlike carbonaceous material according to the results of X-ray photoelectron spectroscopy and Raman spectroscopy. (C) 2003 Wiley Periodicals, Inc.