Final answer:
The reaction of HCl with 1,3-butadiene at room temperature typically results in higher yields of the 1,4-addition product, which is 1-chloro-2-butene, due to its thermodynamic stability.
Step-by-step explanation:
When HCl is reacted with 1,3-butadiene at room temperature, the major product formed is usually the result of a Markovnikov addition where HCl adds across the double bond in a regioselective manner. The resulting product will mainly be 3-chloro-1-butene, which comes from the addition of HCl to the more substituted end of the double bond. In reactions involving conjugated dienes like 1,3-butadiene, there could also be a formation of 1,2-addition vs. 1,4-addition products, with the product distribution being temperature-dependent. At room temperature, the kinetic product, which is the 1,2-addition product, may form in significant amounts, but the thermodynamic product, the 1,4-addition, is generally favored under these conditions and will be in higher yield. The 1,4-addition product for this reaction would be 1-chloro-2-butene.