Photogenerated o-Azaxylylenes: Mechanistic Studies and Synthetic Applications

This research sets out to build upon excited state o-azaxylylene cycloaddition. The mechanism behind the excitation and cycloaddition process of photogenerated o-azaxylylenes was determined experimentally. Time-correlated single-photon counting, steady-state spectroscopy, triplet quenching experiments, and quantum yield studies provided evidence suggesting that excited state intramolecular proton transfer is followed by intersystem crossing and stepwise addition to the tethered unsaturated pendant. In keeping with the principles of diversity oriented synthesis, a modular approach was taken to gain access to a diverse array of N,O,S-Polyheterocycles which were modified postphotochemically via Suzuki coupling to yield fused biaryls. Cycloaddition products, outfitted with halogens in the aromatic ring of the o-azaxylylene, proved to be reactive with a variety of boronic acids resulting in a rapid growth in structural complexity. A novel procedure was developed that utilized multiple o-azaxylylene cores in a photochemical cascade transformation yielding complex scaffolds of unprecedented topology. The photoprecursors were produced in a one-pot two-step sequence from commercially available starting materials, and upon irradiation yield structures containing up to five fused hetrocyclic rings, and showed complete diastereoselectivity.

Desiccant capability of organic xerogels: Surface chemistry vs porous texture

Resorcinol-Formaldehyde xerogels are organic polymers that can be easily tailored to have specific properties. These materials are composed of carbon, hydrogen and oxygen, and have a surface that is very rich in oxygen functionalities, and is therefore very hydrophilic. Their most interesting feature is that they may have the same chemical composition but a different porous texture. Consequently, the influence of porous characteristics, such as pore volume, surface area or pore size can be easily assessed. In this work, a commonly used desiccant, silica gel, is compared with organic xerogels to determine their rate and capacity of water adsorption, and to evaluate the role of surface chemistry versus porous texture. It was found that organic xerogels showed a higher rate of moisture adsorption than silica gel. Pore structure also seems to play an important role in water adsorption capacity. The OX-10 sample, whose porosity was mainly composed of micro-mesoporosity displayed a water adsorption capacity two times greater than that of the silica gel, and three times higher than that of the totally macroporous xerogel OX-2100. The presence of feeder pores (mesopores) that facilitate the access to the hydrophilic surface was observed to be the key factor for a good desiccant behaviour. Neither the total pore volume nor the high surface area (i.e. high microporosity) of the desiccant sample, is as important as the mesopore structure.

Medicinal chemistry : chemistry, biochemistry, therapeutic and pharmacological action of natural and synthetic drugs.

Errata slip inserted in v. 1.

Chemistry : inorganic and organic with experiments /

Includes index.

Chemistry, inorganic and organic, with experiments.

Mode of access: Internet.

Trace organic analysis : a new frontier in analytical chemistry : proceedings of the 9th Materials Research Symposium held at the National Bureau of Standards, Gaithersburg, Maryland, April 10-13, 1978 /

Includes bibliographical references and indexes.

Lecture-notes on chemistry for dental students; including dental chemistry of alloys, amalgams, etc., such portions of organic and physiological chemistry as have practical bearing on the subject of dentistry, an inorganic qualitative analysis with specially adapted blowpipe and microscopical tests, and the chemical examination of urine and saliva,

Mode of access: Internet.

The chemistry of synthetic dyes

Mode of access: Internet.

Chemistry, inorganic and organic, with experiments /

Mode of access: Internet.

Organic and food chemistry,

"List of books consulted": p. 207-208.

Technology of cellulose ethers; a theoretical and practical treatise on the origin, history, chemistry, manufacture, technical application and analysis of the etherified celluloses and carbohydrate carboxylate ehters (esterified cellulose ethers, etherified organic cellulose esters) ...

Paged continuously.

Principles of chemistry; an introductory textbook of inorganic, organic, and physiological chemistry for nurses and students of home economics and applied chemistry, with laboratory experiments,

Mode of access: Internet.

The chemistry and physics of organic pigments.

Bibliography: p. 319-323.