Question

Which intermediate is involved in the reaction shown? Formation and reactions of carbenes with alkenes. The reaction conditions are rather specific for this reaction and probably must be taken into account. The potassium tert-butoxide is a sterically hindered strong base. When trihalomethanes are treated with the strong base, deprotonation gives the trihalomethyl anion, which loses a halide ion to give the neutral carbene. The dihalocarbene adds to the alkene in a a cycloaddition reaction to give the dihalocyclopropane. The cycloaddition reaction is usually stereospecifi, with the stereochemistry of the alkene maintained in the cyclopropane. The acidic nature of the hydrogen atom in the CHCl_3 can be predicted from the stabilizing effect of the three chlorine atoms on the negative charge of the trichomethyl anion. The loss of a chloride ion leads to choice (A), dichlorocarbene. The other choices are structurally implausible.
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Answer 1

The reaction is cyclopropanation reaction cycloroform (chcl_3) acts as an acid towards the base (ch_3) CO^_ K^+ (potassium tert- butoxide). Conjugate base of chcl_3 is formed. From c^bar cl one cl is eliminated under the experience mental conditions to generate dichloro methylene (ccl_2) it a carbine ccl_2 inserts to the alkene (pi bond) in a converted path crasy and cyclopropane ring in formed cyclopropation [2+ 1] cyclo addition the intermediate involved in the reaction is (A) cl - c^..cl