Q1
The rate of an $S_N1$ reaction depends on the concentration of:
📝 Solution$S_N1$ is a two-step mechanism whose rate-determining step is the formation of a carbocation, so rate depends only on substrate concentration (first order).
Q2
Tertiary haloalkanes react faster via the $S_N1$ mechanism mainly because:
📝 SolutionTertiary carbocations are stabilised by hyperconjugation and the electron-donating inductive effect of three alkyl groups, making their formation (the rate-determining step of $S_N1$) faster.
Q3
Primary haloalkanes generally prefer the $S_N2$ mechanism over $S_N1$ because:
📝 SolutionPrimary carbons have low steric hindrance, favouring backside nucleophilic attack ($S_N2$), while primary carbocations are too unstable to favour $S_N1$.
Q4
Grignard reagents are prepared by reacting haloalkanes with:
📝 SolutionGrignard reagents ($RMgX$) are formed by reacting alkyl/aryl halides with magnesium turnings in dry ether.
Q5
The Wurtz reaction converts two molecules of haloalkane into a higher alkane using:
📝 SolutionIn the Wurtz reaction, two molecules of alkyl halide react with sodium metal in dry ether to form a higher alkane with double the carbon atoms: $2RX + 2Na \rightarrow R-R + 2NaX$.
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Class 12 · Chemistry
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