Question

Predict the product(s) you would expect from the treatment of each compound with (1) dilute, neutral and (2) warm basic , then dilute acid.

(a) hex-1-yne (b) hex-2-yne (c) hex-3-yne

(d) 2-methylhex-3-yne (e) cyclodecyne

Short answer

Alkyne is oxidized using the oxidizing agent, e.g., potassium dichromate (KMnO₄), by supplying nascent oxygen.

Alkyne can oxidize in acidic and basic mediums using potassium dichromate(KMnO₄) reagent.

Step-by-step solution

Step 1: Oxidation of Alkyne

Alkyne is oxidized using the oxidizing agent, e.g., potassium dichromate (KMnO₄), by supplying nascent oxygen.

Alkyne can oxidize in acidic and basic mediums using potassium dichromate(KMnO₄) reagent.

Step 2: Product formed when alkyne treated with dilute, neutral KMnO4

Alkyne, when reacted with cold aqueous potassium permanganate under neutral conditions, results in the formation of - diketone while the terminal alkyne forms keto-acid.

(a) Treating hex-1-yne with dilute, neutral KMnO₄forms 2-oxohexanoic acid.

(b) Treating hex-2-yne with dilute, neutral KMnO₄ forms 2-oxopentanoic acid.

(c) Treating hex-3-yne with dilute, neutral KMnO₄ forms hexane-3,4-dione.

(d) Treating 2-methylhex-3-yne with dilute, neutral KMnO₄ forms 2-methylhexane-3,4-dione.

(e) Treating cyclodecyne with dilute, neutral KMnO₄ forms cyclo-1,2-dione.

Product formed when alkyne is treated with warm basic KMnO4 , then dilute acid

Alkyne when react with warm basic then dilute acid forms carboxylic acid while the terminal alkyne form carboxylic acid and carbon dioxide are released out.

(a) Treating hex-1-yne with warm basic KMnO₄ then dilute acid forms pentanoic acid and carbon dioxide is released out.

(b)Treating hex-2-yne with warm basic KMnO₄ then dilute acid forms acetic acid and butyric acid.

(c) Treating hex-3-yne with warm basic KMnO₄ then dilute acid forms two equivalent propionic acids.

(d) Treating 2-methylhex-3-yne with warm basic KMnO₄ then dilute acid forms isobutyric acid and propionic acid.

Formation of isobutyric acid and propionic acid

(e) Treating cyclodecyne with warm basic KMnO₄ then dilute acid forms decanedioic acid.

Formation of decanedioic acid