Predict the product(s) that would result when molecules (a)–(p) are allowed to react under the following conditions: (iii) SOCl₂ , NEt₃ (iv) 1. TsCl, Et₃N 2. NaCN; If no reaction occurs, write 'no reaction.'
(o)

Verified step by step guidance

1. Identify the functional group in the given molecule. The molecule shown is a secondary alcohol, specifically a benzylic alcohol due to the presence of the benzene ring.
2. For condition (iii) with SOCl₂ and NEt₃: Recognize that SOCl₂ (thionyl chloride) is used to convert alcohols into alkyl chlorides. The reaction proceeds via an S_N2 mechanism, which inverts the configuration at the chiral center.
3. Predict the product for condition (iii): The hydroxyl group (OH) will be replaced by a chlorine atom (Cl), resulting in the formation of a benzylic chloride with inversion of stereochemistry.
4. For condition (iv) with 1. TsCl, Et₃N 2. NaCN: Understand that TsCl (tosyl chloride) in the presence of a base like Et₃N converts the alcohol into a tosylate, which is a good leaving group. This is followed by nucleophilic substitution with NaCN.
5. Predict the product for condition (iv): The hydroxyl group is first converted to a tosylate, and then the tosylate is displaced by the cyanide ion (CN⁻) from NaCN, resulting in the formation of a benzylic nitrile with retention of configuration.

Key Concepts

Thionyl Chloride (SOCl₂) Reactivity

Thionyl chloride is a reagent commonly used for converting alcohols into alkyl chlorides. It reacts with alcohols to form the corresponding alkyl chloride and byproducts of sulfur dioxide and hydrochloric acid. Understanding this reaction mechanism is crucial for predicting the products when alcohols are treated with SOCl₂ in the presence of a base like NEt₃, which helps to neutralize the generated HCl.

TsCl and Base Reaction

TsCl, or tosyl chloride, is used to convert alcohols into better leaving groups by forming tosylates. When combined with a base like Et₃N, it facilitates the substitution reaction where the tosylate can be further reacted with nucleophiles, such as NaCN. This process is essential for understanding how to predict the products of reactions involving alcohols and nucleophiles after tosylation.

Nucleophilic Substitution Mechanisms

Nucleophilic substitution is a fundamental reaction in organic chemistry where a nucleophile replaces a leaving group in a molecule. There are two main mechanisms: SN1, which involves a carbocation intermediate, and SN2, which is a concerted reaction. Recognizing the conditions and structure of the reactants helps in determining which mechanism will dominate and thus predicting the final products of the reactions described.