But-2-yne and hydrogen (one mole each) are separately treated with (i) Pd / C and (ii) Na / liq . NH _ 3 to give the products X and Y respectively. Identify the incorrect statements. A. X and Y are stereoisomers. B. Dipole moment of X is zero. C. Boiling point of X is higher than Y. D. X and Y react with O _ 3 / Zn + H _ 2 O to give different products. Choose the correct answer from the options given below :
A. B and D Only
But-2-yne (CH_3-C C-CH_3) undergoes partial hydrogenation. Reaction with Pd/C (Lindlar-like conditions for 1 mole H_2) gives cis-but-2-ene as product X. Reaction with Na/liq. NH_3 (Birch reduction) gives trans-but-2-ene as product Y. Statement A: X (cis) and Y (trans) are geometrical isomers, hence stereoisomers. This is correct. Statement B: Cis-but-2-ene (X) has a non-zero dipole moment ( 0) due to the additive nature of bond moments, while trans-but-2-ene (Y) has zero dipole moment ( = 0) due to symmetry. Thus, statement B is incorrect. Statement C: Cis-isomers generally have higher boiling points than trans-isomers due to higher dipole-dipole interactions. So, B.P. of X > Y. This is correct. Statement D: Reductive ozonolysis (O_3/Zn, H_2O) of both cis-but-2-ene and trans-but-2-ene yields the same product, ethanal (CH_3CHO). Thus, statement D is incorrect. The incorrect statements are B and D.
Related: Chemistry — Hydrocarbons · All PYQ Banks