The major product of the following reaction is:

Step 1: Reaction with DCl (1 equivalent)

The starting material is propyne (CH3-C≡CH). It undergoes electrophilic addition with deuterium chloride (DCl) according to Markovnikov's rule.

1. The electrophile (D+) attacks the terminal carbon to form the more stable secondary carbocation: CH3-C+=CH-D
2. The nucleophile (Cl-) then attacks the carbocation center.

Product after Step 1: CH3-C(Cl)=CHD (2-chloro-1-deuteropropene)

Step 2: Reaction with DI

The alkene product from Step 1 now reacts with deuterium iodide (DI), again following Markovnikov's rule.

1. The electrophile (D+) attacks the terminal carbon because the resulting carbocation at C-2 is highly stabilized by the resonance/lone pair donation of the chlorine atom (carbocation backbonding). CH3-C+(Cl)-CHD2
2. The nucleophile (I-) attacks the C-2 carbocation.

Final Product: CH3-C(Cl)(I)-CHD2

Final Answer

The final major product of the reaction sequence is:

CH3-C(Cl)(I)-CHD2 (2-chloro-2-iodo-1,1-diduteropropane)