- NaOH 2. CICH3 G) 1. NaOEt 2. PhCH2Br 3. H30+, Heat OEt EtO
Show the result and mechanism for these 2 reactions:
The Correct Answer and Explanation is :
Let’s go through each reaction step by step.
Reaction 1: NaOH
This reaction involves sodium hydroxide (NaOH), a strong base, reacting with a substrate. However, you haven’t specified the substrate, so I’ll assume we’re dealing with a common reaction mechanism such as the dehydrohalogenation of an alkyl halide, or the ester hydrolysis.
Let’s assume we’re working with an alkyl halide (R-X), and the reaction is:
R-X + NaOH → R-OH + NaX
This reaction involves the following mechanism:
Step 1: Nucleophilic Substitution
- The hydroxide ion (OH⁻) from NaOH acts as a nucleophile. It attacks the electrophilic carbon atom in the alkyl halide (R-X), which is attached to a halogen (Cl, Br, or I).
- The nucleophile displaces the halide ion, leaving behind the alcohol (R-OH).
The reaction proceeds via SN2 (Substitution Nucleophilic Bimolecular) if the carbon is primary or secondary (typically). In the case of tertiary carbons, the mechanism may proceed via SN1 (Substitution Nucleophilic Unimolecular), where the leaving group departs first, forming a carbocation, which is then attacked by the hydroxide ion.
Reaction 2: NaOEt, PhCH2Br, H3O+, Heat, OEt
This sequence involves several steps:
- Step 1: Nucleophilic Substitution
- NaOEt (sodium ethoxide) acts as a strong nucleophile and attacks the benzyl bromide (PhCH2Br).
- The ethoxide ion (EtO⁻) displaces the bromide ion (Br⁻), leading to the formation of PhCH2OEt (benzyl ethyl ether).
- Step 2: Acid Work-Up
- After this nucleophilic substitution, the reaction is treated with H₃O⁺ (acidic work-up), which will protonate the ether and help in its final preparation.
- Step 3: Heating
- The reaction mixture is heated to promote the ether formation. Heat is often used to encourage substitution reactions and eliminate any byproducts.
In this sequence, the key mechanism is SN2 because the benzyl carbon (PhCH2) is primary, making it favorable for backside attack by the ethoxide ion.
Conclusion:
- NaOH typically leads to nucleophilic substitution or ester hydrolysis.
- NaOEt, PhCH2Br, H3O+, Heat, OEt involves an SN2 reaction, where the ethoxide ion displaces the bromide from the benzyl group to form a benzyl ethyl ether.