Show how each compound might be synthesized by the SN2 displacement of an alkyl halide. e. H2C=CH—CH2CN f. H—C≡C—CH2CH2CH3

Verified step by step guidance

1. Identify the target molecules: H2C=CH—CH2CN and H—C≡C—CH2CH2CH3.
2. For H2C=CH—CH2CN, choose an appropriate alkyl halide and nucleophile. The alkyl halide should be H2C=CH—CH2X, where X is a good leaving group (e.g., Br or I). The nucleophile should be CN-.
3. For H2C=CH—CH2CN, perform an SN2 reaction where the nucleophile (CN-) attacks the carbon attached to the leaving group (X) in H2C=CH—CH2X, resulting in the displacement of X and formation of H2C=CH—CH2CN.
4. For H—C≡C—CH2CH2CH3, choose an appropriate alkyl halide and nucleophile. The alkyl halide should be X—CH2CH2CH3, where X is a good leaving group (e.g., Br or I). The nucleophile should be H—C≡C-.
5. For H—C≡C—CH2CH2CH3, perform an SN2 reaction where the nucleophile (H—C≡C-) attacks the carbon attached to the leaving group (X) in X—CH2CH2CH3, resulting in the displacement of X and formation of H—C≡C—CH2CH2CH3.

Key Concepts

SN2 Mechanism

The SN2 (substitution nucleophilic bimolecular) mechanism involves a nucleophile attacking an electrophilic carbon atom, leading to the simultaneous displacement of a leaving group. This reaction is characterized by a single concerted step, where the nucleophile approaches the carbon from the opposite side of the leaving group, resulting in an inversion of configuration. The rate of the reaction depends on the concentration of both the nucleophile and the substrate.

Alkyl Halides

Alkyl halides are organic compounds containing a carbon atom bonded to a halogen atom (F, Cl, Br, or I). They serve as key substrates in SN2 reactions due to the polar nature of the carbon-halogen bond, which makes the carbon atom electrophilic. The reactivity of alkyl halides in SN2 reactions generally decreases with increasing steric hindrance, making primary alkyl halides the most favorable for this mechanism.

Nucleophiles

Nucleophiles are species that donate an electron pair to form a chemical bond in a reaction. In the context of SN2 reactions, a strong nucleophile is essential for effectively attacking the electrophilic carbon of the alkyl halide. Common nucleophiles include anions like hydroxide (OH-) or alkoxides (RO-), as well as neutral molecules with lone pairs, such as amines. The strength and sterics of the nucleophile significantly influence the reaction rate and outcome.