Heat exchange configurations for oligomerization of olefins

A process comprising:

• a) introducing at least 1) ethylene, 2) a catalyst system or catalyst system components comprising i) a heteroatomic ligand transition metal compound complex and an organoaluminum compound or ii) a heteroatomic ligand, a transition metal compound, and an organoaluminum compound, 3) optionally, an organic reaction medium, and 4) optionally, hydrogen into a reaction mixture within a reaction zone;
• b) forming an oligomer product in the reaction zone;
• and
• c) controlling a reaction mixture temperature within the reaction zone with a heat exchange system comprising a first heat exchanger providing indirect contact between at least a portion of the reaction mixture and a first heat exchange medium, the first heat exchanger comprising a first heat exchange surface having
• i) a first heat exchange surface first side in contact with the at least a portion of the reaction mixture, and
• ii) a first heat exchange surface second side in contact with the first heat exchange medium:
• where a pressure on the first heat exchange surface second side is less than 1 atmosphere (101.3 kPa),
• where the first heat exchange medium has a boiling point at 1 atmosphere (101.3 kPa) greater than an average reaction mixture temperature on the first heat exchange surface first side and a boiling point at the pressure on the first heat exchange surface second side less than the average reaction mixture temperature on the first heat exchange surface first side, and
• where a temperature difference between the average reaction mixture temperature on the first heat exchange surface first side and a first heat exchange medium temperature on the first heat exchange surface second side is less than 20° C.