H_3C-CH=CH_2 + HCl rarr H_3C-C(Cl)H-CH_3
The 2^@ alkyl halide would be the major product, as it derives from the more stable 2^@ carbocation.
Propylene is a nucleophile that first reacts with H^+ to give a carbocation intermediate:
H_3C-CH=CH_2 + HCl rarr H_3C-C^+H-CH_3 +Cl^-
The alternative product of addition, H_3C-CH_2C^+H_2, features a primary carbocation as the intermediate (to give H_3C-CH_2CH_2Cl). This is a higher energy (less stable) customer than the 2^@ carbocation, and thus the reaction tends to proceed thru the lower energy 2^@ carbocation. H_3C-C(Cl)H-CH_3 should thus be the major product of reaction.
You should check the details of this reaction with your organic chemistry text.
