John C. Warner

Concentration of bisphenol A in thermal paper

Abstract Bisphenol A (BPA) is widely used as a color developer in thermal paper. Thermal paper is ubiquitous in daily life due to its use in cash register receipts, so opportunities for human contact abound. For this study, 10 blank cash register receipts were obtained from businesses in suburban Boston. BPA was extracted and analysis of concentration was performed using gas chromatograph/flame ionization detector. In some receipts, BPA was not detected but in others it was as high as 19 mg for a 12-inch long receipt, which is in line with concentrations indicated in patents. This study is intended to highlight the potential for human exposure to BPA as well as the ease with which exposure may be reduced through the use of BPA-free thermal paper.

N-nitrosamines via the phase-transfer mediated nitrosation of secondary amines with sodium nitrite and n-haloamides

Abstract Secondary amines are cleanly and readily converted to the corresponding N-nitrosamines in high yield under phase-transfer conditions by means of soduim nitrite and N-halo-amides; the active nitrosating agent is presumed to be dinitrogen tetroxide.

Enzymatic Reversal of Polymeric Thymine Photocrosslinking with E. coli DNA Photolyase

Polymers containing pendant thymine groups undergo a 2π+2π cycloaddition crosslinking reaction. The enzyme DNA photolyase has been demonstrated to reverse this photocrosslinking in thymine containing styrene derivatives.

Non-Covalent Derivatives: Cocrystals and Eutectics

Non-covalent derivatives (NCDs) are formed by incorporating one (or more) coformer molecule(s) into the matrix of a parent molecule via non-covalent forces. These forces can include ionic forces, Van der Waals forces, hydrogen bonding, lipophilic-lipophilic interactions and pi-pi interactions. NCDs, in both cocrystal and eutectic forms, possess properties that are unique to their supramolecular matrix. These properties include critical product performance factors such as solubility, stability and bioavailability. NCDs have been used to tailor materials for a variety of applications and have the potential to be used in an even broader range of materials and processes. NCDs can be prepared using little or no solvent and none of the reagents typical to synthetic modifications. Thus, NCDs represent a powerfully versatile, environmentally-friendly and cost-effective opportunity.

Environmentally benign synthesis using crystal engineering : Steric accommodation in non-covalent derivatives of hydroquinones

The solid state phase behavior of hydroquinone 1 with bis-(N,N-diethylamino)terephthalamide 2 and with bis-(N,N-dimethylamino)terephthalamide 3 has been investigated. Stoichiometric cocrystals have been prepared of the identified stable complexes. X-ray structure determinations of these cocrystals have been performed. The role of the alkyl side chains in the crystal packing geometry is discussed.

Methylene blue adsorption on thymine based polyvinylphenylsulfonate films

The immobilization of thymine‐containing copolymers of vinylphenylsulfonate (VPS) and vinylbenzylthymine (VBT) on a nonreactive substrate has been investigated. These polymers are environmentally benign, water‐soluble and when irradiated with low levels of UV light undergo a 2π+2π photodimerization reaction of the thymine moieties. These photoinduced dimers form a crosslinked network that renders the polymer significantly less soluble in water. Consequently the irradiated polymer is immobilized on the substrate, allowing removal of unexposed regions by simple aqueous wash. Visualization of the photoresist is done by “toning” the remaining anionic copolymer with the cationic dye methylene blue. By evaluating the color density of the crosslinked, toned films by UV‐Vis spectroscopy, this report describes the impact of copolymer composition and curing conditions on polymer photoreactivity. Mechanistic rationale is proposed.

Diels-Alder Reactions of Bicyclic 1,2,4-Triazines: The Conversion of Pyrimido[4,5-e]-1,2,4-triazines to Pyrido[2,3-d]pyrimidines (5-Deazapteridines)☆☆☆

Abstract Inverse electron-demand cycloaddition of aldehyde enamines with 6-azapterins and 6-azalumazines (pyrimido[4,5- e ]-1,2,4-triazines) leads regiospecifically to 6-substituted 5-deazapterins and 5-deazalumazines (pyrido[2,3- d ]pyrimidines) respectively. 5,6-Fused cyclopenteno and cyclohexeno derivatives are formed with enamines derived from cyclopentanone and cyclohexanone respectively.

Core-shell thymine containing polymeric micelle system: study of controlled release of riboflavin

Abstract A series of bioinspired poly(vinylbenzylthymine)-b-poly(vinylphenylsufonate) was synthesized and its core-shell thymine containing polymeric micelle system was prepared. The study of control release of riboflavin with micelles was examined by photometrical assay and demonstrated that the guest materials could be encapsulated by hydrogen bonding with the attached thymine in the core.

THE SCIENCE OF GREEN CHEMISTRY AND ITS ROLE IN CHEMICALS POLICY AND EDUCATIONAL REFORM

Over the past 10 years, the science of green chemistry has continued to evolve and has been adopted in research labs in industry and academia. At the same time, new innovations in chemicals policy have widened opportunities for legislative action to protect human health and the environment. This article addresses the mechanisms by which the science of green chemistry and chemicals policy can work together to help attain a more sustainable future. It also speaks to the pitfalls of inappropriately merging these two, and explores how such a merger could inhibit the creation of sustainable technologies. Green chemistrys role in educational reform is discussed as a means for training students who are prepared to create truly sustainable technologies.

Core-bound polymeric micellar system based on photocrosslinking of thymine

Bioinspired core-bound polymer micellar aggregates were synthesized by photocrosslinking thymine-functionalized cores using short UV irradiation; H-bonding between thymines in the core is also believed to increase micellar aggregate stability.