Propynoic acid, trimerization

In the cyclotrimerization of propynoic acid, trimellitic (l,2,4-fb,l l3((X)2H),) and trimesic acid (l,3,5-CgH3(CO2H)3) are obtained as the product of head-to-head or head-to-tail linkage, respectively. For the sake of comparison, reactions were conducted both in neat water and in neat THF. In all cases, the yield of the trimer was higher in the aqueous system, evidencing the high tolerance of the rhodium catalyst towards water. 

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