[jiangds05]

if these two are competing reaction, what should I do to suppress intermolecular reaction by physical means. for example, temperature change, concentration decrease and viscosity of solvent?
thanks a lot if you can help. 

[democanarchis]

An intermolecular reaction should be entropically disfavoured anyway, in a dilute solution the intermolecular reaction should be further slowed. Decreasing the temperature may have an effect if the intramolecular reaction is more thermodynamically favoured. Is there a specific reaction that you are trying to optimise?

[jiangds05]

no, I just ask for general question. thanks a lot.
do you think increase solution viscosity will help?

An intermolecular reaction should be entropically disfavoured anyway, in a dilute solution the intermolecular reaction should be further slowed. Decreasing the temperature may have an effect if the intramolecular reaction is more thermodynamically favoured. Is there a specific reaction that you are trying to optimise?