A polarographic study of mesityl oxide and its determination in diacetone alcohol by fast-scan, phase-sensitive, A.C. polatography
✍ Scribed by B. Fleet; R.D. Jee; C.J. Little
- Book ID
- 104149448
- Publisher
- Elsevier Science
- Year
- 1973
- Weight
- 594 KB
- Volume
- 43
- Category
- Article
- ISSN
- 0022-0728
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✦ Synopsis
Diacetone alcohol (1) is a widely used solvent in the formulation of pesticides. It is decomposed to mesityl oxide (II) according to the following reaction:
(CH 3)2COH • CH 2COCH 3 --* (CH3)2C : CHCOCH 3 I II Consequently its analysis is important in formulation and quality control analysis. The most obvious technique to try is that of gas liquid chromatography (G.L.C.). Unfortunately, unless low temperatures and carefully prepared columns are used, the major response obtained is due to mesityl oxide, complete decomposition having occurred on the column. Therefore, the polarographic technique was investigated as an alternative. This technique is ideally suited since diacetone alcohol itself is electro-inactive, while mesityl oxide, under suitable conditions, gives well defined polarograms. Furthermore, as polarography is a trace technique, it is suited to the type of analysis required.
A brief study ~ of the determination of mesityl oxide in diacetone alcohol and acetone has been published and is based on the conditions established by Pasternak 2. The present re-investigation has shown that the conditions employed in this study are far from ideal. Most of the published work on this problem has been concerned with electrochemical syntheses and problems such as the effect of methylic substitution on half wave potentials of unsaturated carbonyl compounds 3, and hydrodimerisation reactions ~-6, and has made little contribution to either the analytical problem or the mechanism of the electrode reaction.
The present work examines the polarographic behaviour of mesityl oxide and suggests an overall mechanism of the electrode process. A wide range of techniques have been used including normal and fast sweeps in the d.c. and a.c. mode, culminating in the use of phase-sensitive detection of the a.c. signal. It is shown that for reasons of greater speed and sensitivity, the latter technique is the method of choice for analytical purposes and possesses the additional advantage of the inherently more precise measurement of peak height rather than wave height 7. This becomes a critical point at very low levels of mesityl oxide. EXPERIMENTAL Apparatus D.c. polarograms were recorded on a Radelkis type OH-102 polarograph. A