Of 4-methylpentane-2-one

Lead caprate. Prepare a standard stock solution by dissolving 0.1323 g of the solid in 2 mL of naphthenic acid with warming. Add 20 mL of 4-methylpentan-2-one (methyl isobutyl ketone), cool and then make up to the mark in a 100 mL graduated flask with more of the ketone. 

Transfer the solution to a 250 mL separatory funnel, rinsing out the beaker with a little water. Add 5 mL of the 2 per cent NaDDC reagent and allow to stand for one minute, and then add a lOmL portion of 4-methylpentan-2-one (methyl isobutyl ketone), shake for one minute and then separate and collect the organic layer. Return the aqueous phase to the funnel, extract with a further lOmL portion of methyl isobutyl ketone, separate and combine the organic layer with that already collected. Finally, rinse the funnel with a little fresh ketone and add this rinse liquid to the organic extract. In these operations the lead is converted into a chelate which is extracted into the organic solvent. 

Ketones. Normal acyclic ketones can be recognised by a strong band at 1720 cm -1 (e.g. see the spectrum of 4-methylpentan-2-one, Fig. 3.28). Branching at the a-carbon atoms results in an increase in the C—CO—C bond angle and this results in a decrease in frequency of absorption from the normal value of 1720 cm -1 to, for example, 1697 cm -1 as in di-t-butylketone. Conversely as the C—CO—C bond angle is decreased the absorption frequency rises, thus cyclo-pentanone and cyclobutanone absorb at 1750 cm-1 and 1775 cm-1 respectively. 

Thus the spectrum of 4-methylpentan-2-one (Fig. 3.84) shows a strong peak at m/z due to the odd-electron ion (CH3C(OH)=CH2) resulting from the McLafferty rearrangement. 

Ambrose, D., Ghiassee, N.B., Tuckerman, R. (1988) Vapom pressure and critical temperature and critical pressure of 4-methylpentan-2-one. J. Chem. Thermodyn. 20, 767-768. 

The influence of naphthalene on the photoreaction of 4-methylpentan-2-one in solution has been evaluated. 

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