A Selection of Grapes

This undistinguished, productive, drought resistant, vigorous white grape, Airén, from the La Mancha region of Spain, was said to be the most widely planted grape in the world. In part the justification for this claim relies upon the observation that it is planted at a very low density! Except for its use in blending to make other wines “lighter,” it has not found wide accep¬tance. In part, it appears that its lack of popularity is the result of what is reported to be a mild, neutral flavor, and advertising has not pushed wines produced from it to the fore. Although it is now common to attempt to analyze the headspace (or ullage) in bottled wine (as well as the wine itself ) by chromatographic and mass spectrometric techniques it is less common to find that the grapes (skin, must, and seeds) are also subjected to such analysis. Nonetheless, the phenolic composition of V. vinifera var Airén was subjected to just such analysis during ripening from véraison to “technological” maturity (i.e., maturity which might actually be earlier than harvest, the latter being the decision of the viticulturist and vintner). The analysis of the ethyl ether extract of macerated skins, seeds, and accumulated solids (the pomace) was undertaken. Procyanidins and anthocyanins which would (the authors claim) interfere with subsequent analysis would not move into the ether phase. It was also found (using controls) that other highly polar materials (e.g., carboxylic acids) were only poorly extracted from the macerated skins and seeds. The isolated compounds and some information about their sources are provided in Figures 14.1 and 14.2. The analysis of the seeds, skin, and must did lead to the conclusion that “the maximum concentrations of benzoic and cinnamic acids and aldehydes and flavonol aglycones and glycosides at the end of the ripening period did not coincide with the minimum concentrations of the flavan-3-ols and hydroxycinnamic tartaric esters.” Depending upon what was sought, this information might thus affect decisions concerning the harvest date.

Preparation and application of 4′-carboxybenzo-15-crown-5, a drift-type crown ether phase transfer catalyst

A new "drift-type" crown ether phase transfer catalyst, 4′-carboxybenzo-15-crown-5 adsorbed on poly(styrene/divinylbenzene)-NR2 resin, was synthesized and applied to catalyze the oxidation of benzhydrol with NaMNO4 as an oxidant. Before the reaction, the drift-type crown ether catalyst was adsorbed on the resin with ion-pair (resin-NR2H+−O2C-monobenzo-15-crown-5) formation. During the reaction period the crown ether catalyst was released from the resin into the reaction solution as a homogeneous catalyst by adjusting the acidity of the solution to 10−1 M HCl to destroy the ion pair between the catalyst and the resin. After the reaction, the crown ether catalyst could be readsorbed on the resin by adjusting the concentration of HCl to 10−5 M and could be readily recovered by filtration. The catalyst, 4′-carboxybenzo- 15-crown-5, was found to be a more effective catalyst than other crown ethers, such as 15-crown-5, 18-crown-6, monobenzo-15-crown-5, and dibenzo-18-crown-5.