The formation of undesired side products can be attributed to several factors: - Non-selectivity of the Catalyst: Catalysts that are not highly selective may facilitate multiple reaction pathways, leading to a mixture of products. - Reaction Conditions: Factors such as temperature, pressure, and solvent can influence the selectivity and rate of side reactions. - Reagent Purity: Impurities in the starting materials can react to form unintended products. - Deactivation of Catalyst: Over time, catalysts can degrade or become poisoned, leading to a decrease in selectivity and an increase in side products.