Final answer:
In the chlorination of alkanes, the presence of a phenyl group, as seen in 1-chloro-1-phenylethane, stabilizes the carbocation intermediate, making it the major product. Alkenes like ethylene react with chlorine to form dichlorides, and conditions favoring high alkane concentrations help minimize side products and promote the formation of desired haloalkanes for further reactions.
Step-by-step explanation:
In a chlorination reaction, the distribution of products can vary depending on factors such as reaction time, temperature, and the reactivity of the starting material. For example, the chlorination of an alkane like ethane can produce a mixture of chlorinated products including dichloromethane, trichloromethane (chloroform), andtetrachloromethane (carbon tetrachloride). The presence of a phenyl group in 1-chloro-1-phenylethane, being an electron-releasing group, stabilizes the carbocation intermediate formed during the reaction, which leads to it being the major product over 1-chloro-2-phenylethane, which would form a less stable intermediate. Furthermore, the reaction of chloroalkanes with hydrofluoric acid (HF) can lead to the production of chlorofluorocarbons (CFCs), where the fluorine atom exhibits a strong preference for bonding with carbon.
When alkenes such as ethylene are reacted with chlorine, the product is usually ethylene dichloride. Halogenation of alkenes occurs relatively easily under mild conditions, often spontaneously, but if hydrogen is added across the alkene's double bond in a hydrogenation reaction, harsher conditions such as high pressures of H2 and the use of platinum or palladium catalysts may be required.
The industrial production of haloalkanes typically involves conditions that favor the formation of the desired product and minimize side products. This includes the use of high concentrations of the initial alkane, which makes the reaction more selective towards the formation of more reactive haloalkanes. These reactive haloalkanes can be used in further polar reactions.