Mechanism for the addition of carbenoid CH2ClLi to formaldehyde

Ab initio HF/6-31G* calculations have been performed for the addition mecha nism of carbenoid CH2CILi with formaldehyde in tetrahydrofuran. An early co mplex of formaldehyde with CH2CILi is first formed with quite exothermic ef fect. Only a little activation energy of 14.6 kJ/mol is needed for the comp lex developing into the product through a transition state with coplanar bi cyclic structure. In this process, the eletrophilic attack of carbonyl carb on of formaldehyde is more active than the nucleophilic attack of carbon of carbenoid. The exothermal effect of this addition process is up to 216.5 k J/mol.