Chemistry of carbon rich star IRAS 15194-5115

We have constructed two gas-phase models to study the chemistry of circumstellar envelope surrounding the carbon-rich variable star IRAS 15194-5115. The network used consists of 3893 reactions involving 397 gas-phase species. The derived fractional abundances for many molecules are in excellent agreement with values obtained from observations. The predicted column densities from the two models go well with the observed values of carbon star IRC + 10216. The dominant formation routes for three groups of species are discussed through the inner and outer envelopes.