The product mixtures obtained by reaction between phenyllithium and carbon monoxide in diethyl ether, followed by hydrolysis, include benzophenone (1). a,a-diphenylacetophenone (2), benzil (3), a,a-diphenyl- a-hydroxyacetophenone (4), benzpinacot (5), a-hydroxyacetophenone (6), 1,3,3-triphenylpropane-1,2-dione (7), 1,3,3-triphenylpropan-1-one-2,3-diol (8). and benzhydrol (9). Compounds 1, 2, 6,7, and 8 are produced in signifi- cant yields i 3,4,5, and 9 are produced in trace quantities. Spectroscopic studies establish dilithium benzophenone dianion (18) as the first long-lived intermediate formed in this reaction; qualitative correlations between the basicity of a number of organolithium reagents and their reactivity toward carbon monoxide suggests, but does not prove, that benzoyllithium is a precursor of 18. Labeling experiments indicate that the products ultimately isolated following hydrolysis of the reaction mixture are derived from at least two pathways which compete for the initially formed 18. One involves combination of l8 with 1 equiv of phenyllithium and 1 equiv of carbon monoxide, followed by elimination of I equiv of lithium oxide. yielding 17, the lithium enolate of 2; a second involves com- bination of 18 with 1 equiv of phenyllithium and 2 equiv of carbon monoxide. yielding 22,the trilithium trianion of 8. Hydrolysis of l7 yields 2 directly. Hydrolysis of 22 yields 8; reverse aldol reactions involving 8 or its pre- cursors generate 1 and 6. The mechanism proposed to account for the major products of the reaction of phenyl- lithium and carbon monoxide is outlined in Scheme III On the basis of this scheme, plausible paths to the minor products of the reaction are proposed.