[hermeem83]

What are the two alkenes, which contain only one double bond, that yeild exclusively propanoic acid upon oxidation with hot concentrated KMnO4?

[lemonoman]

To answer this, we need to know:

What effect does KMnO4 have on alkenes?

[Rico]

Alkenes undergoes oxidative cleavage upon treatment with KMnO4 in acid. The two alkenes that yield exclusively propanoic acid must then be 3-hexene and 1-butene.

CH3CH2CH=CHCH2CH3 -> CH3CH2COOH + HOOCCH2CH3
        3-hexene


CH3CH2CH2=CH2 -> CH3CH2COOH + CO2
     1-butene

1-butene yields exclusively propanoic acid since the carbon dioxide bubbles out of the reaction mixture.

[sjb]

CH3CH2CH2=CH2 -> CH3CH2COOH + CO2
     1-butene

1-butene yields exclusively propanoic acid since the carbon dioxide bubbles out of the reaction mixture.

Good spot! I hadn't thought of that argument

Make that 3 alkenes that give propanoic acid then....

[AWK]

There are two isomers of 3-hexene