See image — Haloalkanes and Haloarenes Chemistry Question

💡 Solution & Explanation

Step 1 - Identify the reaction type. The reagent K+t-BuO- (potassium tert-butoxide) is a bulky, strong, non-nucleophilic base. Under E2 conditions it promotes elimination. Step 2 - Identify the substrate structure. The central carbon bears four different groups: CH3, Ph, CD3 (deuterated methyl on wedge), and Br (on dash). This is a tertiary-like carbon, but more precisely it is a carbon with Ph, CH3, CD3, and Br. For E2 elimination, the base removes a beta-hydrogen (or beta-deuterium) anti-periplanar to the leaving group (Br). Step 3 - Determine what beta hydrogens/deuteriums are available. The groups attached to the central carbon are Ph, CH3, CD3, and Br. The CH3 group has three H atoms (beta hydrogens) and the CD3 group has three D atoms (beta deuteriums). E2 elimination requires anti-periplanar alignment of the beta-H (or D) and the Br. Step 4 - Determine the product. E2 elimination removes HBr (or DBr) from the substrate. The central carbon loses Br and a hydrogen (or deuterium) from either CH3 or CD3 is removed. This generates a double bond between the central carbon and either the CH2= (from CH3) or CD2= (from CD3) carbon. The product is an alkene: Ph-C(=CH2)-CD3 or Ph-C(=CD2)-CH3. Step 5 - Assess chirality of product. The alkene carbon that was formerly the stereocenter is now sp2 hybridized (trigonal planar). An sp2 carbon cannot be a stereocenter. Therefore, the chiral center is destroyed upon formation of the double bond. Step 6 - Evaluate the options. (a) Inversion implies the stereocenter still exists but with opposite configuration - not applicable since the stereocenter is gone. (b) Retention implies the stereocenter still exists with the same configuration - not applicable. (c) Racemization implies equal mixture of both enantiomers - not applicable; there is no chiral center at all. (d) Loss of chirality (product is achiral) - correct, because the sp2 carbon in the alkene product is no longer a stereocenter. Therefore, the correct answer is D.