Let's break down the problem step by step: --- ## (a) **Type of Reaction** The reaction shown is: \[ \ce{R-S-CH2CH2CH2Cl + H2O -> R-S-CH2CH2CH2OH} \] Where \(\ce{R-S-}\) is a thioether group. **Type of Reaction:** This is a **nucleophilic substitution** reaction. Specifically, it appears to be an **SN1** or **SN2** substitution, where the \(\ce{Cl}\) is replaced by an \(\ce{OH}\) group from water. --- ## (b) **Step-by-Step Mechanism** Let's analyze the mechanism. Since the starting compound is a primary alkyl halide (the chloride is on a primary carbon), the reaction will most likely proceed via an **SN2 mechanism** (bimolecular nucleophilic substitution). ### Step 1: Nucleophilic Attack - Water (\(\ce{H2O}\)) acts as a nucleophile. - It attacks the carbon attached to the chlorine (\(\ce{Cl}\)), simultaneously displacing the chloride ion (\(\ce{Cl^-}\)). - This is a **one-step mechanism** (concerted process). **Mechanism Diagram:** ``` R-S-CH2CH2CH2-Cl + H2O → R-S-CH2CH2CH2-OH + HCl ``` **Curved Arrows:** 1. Lone pair on oxygen of water attacks the electrophilic carbon (carbon attached to Cl). 2. The bond between carbon and chlorine breaks and chlorine leaves as \(\ce{Cl^-}\). ### Step 2: Deprotonation - The product from the first step is a protonated alcohol (\(\ce{R-S-CH2CH2CH2-OH2^+}\)). - A base (often another water molecule) removes a proton (\(\ce{H^+}\)) from the oxygen, yielding the neutral alcohol (\(\ce{R-S-CH2CH2CH2-OH}\)). --- ## **Overall Reaction** \[ \ce{R-S-CH2CH2CH2-Cl + H2O ->[SN2] R-S-CH2CH2CH2-OH + HCl} \] --- ## **Summary Table** | Step | Description | Species Involved | |------|-------------------------------------------|----------------------------| | 1 | Nucleophilic attack (SN2) | Water, alkyl chloride | | 2 | Deprotonation of protonated alcohol | Protonated alcohol, water | --- ## **Final Answer** ### (a) **Type of reaction:** Nucleophilic substitution (SN2). ### (b) **Step-by-step mechanism:** 1. Water attacks the electrophilic carbon, displacing chloride (SN2). 2. Water deprotonates the resulting oxonium ion to give the alcohol. **Final Product:** \[ \ce{R-S-CH2CH2CH2-OH} \]