The apparent activation energies and pre-exponential factors for the Rochow reaction, determined from reaction rate measurements at 280-360 degrees C, strongly change, if contact masses are varied with respect to promoters, to the copper component’s nature and percentage as well as to the silicon type. With each variation, the activation parameters consequently follow the same Cremer-Constable relation. The isokinetic temperature is in the range 330 +/- 20 degrees C, i.e., within the region of the reaction temperatures. This implies that the sequence of activities of compared contact masses can be reversed by a mere temperature variation. This may be a reason of contradictions in the literature on Rochow synthesis.