Andrew E. Graham

Diels–Alder reactions between maleic anhydride and furan derivatives in supercritical CO2

A comparative analysis of the reactions between maleic anhydride and furan derivatives is presented in near and supercritical carbon dioxide and traditional organic solvents. Reaction kinetics were monitored by UV-vis absorbance spectroscopy in conjunction with an optimization technique which greatly simplified the experimental approach. In all of the reactions studied, supercritical carbon dioxide proved to facilitate a rate enhancement over conventional organic solvents. The reaction between maleic anhydride and furfuryl alcohol at 69 bar and 35 °C was found to proceed 10 times faster in CO2 compared to reactions carried out in diethyl ether. All kinetic results were obtained from reactions undertaken in true homogeneous one phase fluid systems. The results achieved further indicate the potential of using carbon dioxide as a medium to carry out such chemical transformations through more environmentally acceptable processes.

Rapid ring-opening reactions of epoxides using microwave irradiation

Abstract Copper tetrafluoroborate catalyzes the ring‐opening of epoxides with primary, secondary, and tertiary alcohols in short reaction times under microwave irradiation to give β‐alkoxyalcohol products in excellent yields.

Desymmetrization of diols by a tandem oxidation/Wittig olefination reaction.

Diols are desymmetrized by a tandem oxidation/Wittig olefination to give alpha,beta-unsaturated hydroxy esters without the requirement for protecting group strategies; the alpha,beta-unsaturated hydroxy esters are transformed into dienyl diesters using a second oxidation/Wittig olefination sequence using PCC.

Accurate mass measurement by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry. I. Measurement of positive radical ions using porphyrin standard reference materials: Accurate mass MALDI of positive radical ions using porphyrins

A method for the accurate mass measurement of positive radical ions by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOFMS) is described. Initial use of a conjugated oligomeric calibration material was rejected in favour of a series of meso-tetraalkyl/tetraalkylaryl-functionalised porphyrins, from which the two calibrants required for a particular accurate mass measurement were chosen. While all measurements of monoisotopic species were within +/-5 ppm, and the method was rigorously validated using chemometrics, mean values of five measurements were used for extra confidence in the generation of potential elemental formulae. Potential difficulties encountered when measuring compounds containing multi-isotopic elements are discussed, where the monoisotopic peak is no longer the lowest mass peak, and a simple mass-correction solution can be applied. The method requires no significant expertise to implement, but care and attention is required to obtain valid measurements. The method is operationally simple and will prove useful to the analytical chemistry community.