Changing Starting Materials Ratio

There is one reaction between A and B. The ratio of A/B in the literature is 1:1.2, that is, theoretically A is excess. But after the reaction, it was found that the excessed A is very hard to separate from the product C. So the reaction ratio was modified to A/B =  0.9:1. By this, even though the yield was kind of less, pure product was obtained much more easily.