The gas-phase ion-molecule reactions of CD3+ + C2H6 and of CD3+ + C3H8 were investigated in a guided ion beam apparatus. Several basic reaction mechanisms such as hydride, methylene, and ethylene transfer as well as eliminative and double-eliminative association were observed. Absolute integral cross sections were measured at collision energies ranging from 0.1 to 5 eV. The branching ratios are in good agreement with recent ion cyclotron resonance results. Velocity distributions of products (especially of very slow ones) were recorded by the guided ion beam time-of-flight (GIB-TOF) method. Thereby, direct type of reaction and reaction via a long-lived complex are distinguished. In contrast to previous crossed beam experiments, the hydride transfer has been identified to proceed via a direct mechanism, even at low collision energies. Partitioning of the total available energy into translational energy and internal excitation is estimated as a function of total energy.