[Athiril]

Given that KMnO4 oxidises primary alcohols to aldehydes and secondary alcohols to ketones, and that in a mixture secondary alcohols will oxidise first (correct?).

What's the order of preference of primary alcohols that will most readily oxidise first.

The highest molecular weight first?

The lowest molecular weight first? (If so would that be methyl alcohol or ethyl alcohol, since methyl alcohol doesn't fit the general classification of primaries?)

Or is it arbitrary?

Is there a difference in preference in acidic vs basic conditions?

Is there any reference for this? Or further reading?

[orgstudy]

* KMnO4 converts primary alcohol to acid (if with H+) and to aldehyde (if neutral)

Well i'm not sure about the neutral case!!!!!

[AndersHoveland]

Permanganate will oxidize alcohols to aldehydes or ketones, and then rapidly oxidizes the aldehydes to carboxylic acids. The reaction rate for the oxidation of aldehyde is apparently much faster than oxidation of the original alcohol.
Using dilute solutions of permanganate with excess alcohol can result in low yields of aldehydes (I think typically only around 10% yield relative to the carboxylic acids formed).

[fauq]

Use PCC (pyridinium chlorochromate) for oxidizing primary alchols to aldehydes without further oxidation.

[AndersHoveland]

Yes, PCC is an interesting regent. Mild oxidixing agents, such as pyridinium chlorochromate, can oxidize the 3-hydroxyl azetidine to the ketone,
azetidine-3-one, leaving the ring intact. (This is one of the steps for one of the synthesis routes for TNAZ)

Of course, the pyridinium cation has nothing to do with the actual reaction, it only makes the chlorochromate soluble (actually a suspension) in organic solvents.