We have studied in situ the adsorption of a soluble anionic dye polymer onto spread monolayers by means of reflection spectroscopy. We found that the adsorption is governed by the charge neutrality; the ratio of the adsorbed polymer unit and the cationic monolayer molecule is nearly 1:l for the surface density in the range of 50-77 &/monolayer molecule. On the other hand, no adsorption occurs onto an anionic monolayer. We have also investigated the adsorption kinetics of the polymer. The rate of adsorption can be reproduced very well with a simple diffusion simulation.

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In-pore' reactions of 15-hydroxypentadecanoic acid on dealuminated HY zeolite effected intramolecular esterification exclusively to give the monomeric lactone, pentadecanolide.Even if large ring compounds are generally stable, they are often difficult to synthesize from chain compounds; intermolecular reactions are more likely to occur than intramolecular ring closure. Preparation of large ring lactones from the corresponding o-hydroxy acids suffers from this synthetically difficult problem. Several techniques with this specific problem in mind have recently been developed, and these are generally based on high dilution, some form of functional activation through prior derivatisation, and/or template effect of catalytic esterification agents.1Zeolites are structurally unique in having cavities or pores with molecular dimensions. Acidic catalytic sites within such a structure provide the basis of molecular shape-selective catalysis.2.3 A particular type of shape selectivity, product selectivity, arises when, among the multiplicity of products that could be formed, only those with the appropriate shape and size can pass through the channels as products. Increasing attention is being paid to zeolites as catalysts or reagent supports in fine chemical synthesis.4.5 It occurred to us that acid catalysed reaction of o-hydroxy carboxylic acids might be constrained in such a shape-selective environment to effect internal macrocyclic esterification selectively, repressing intermolecular esterification leading to dimeric and polymeric condensation. We now report on a synthetically useful new approach towards the preparation of pentadecanolide (exaltolide) , an important perfume constituent included in angelica

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