Infrared and millimeter-wave measurements of the environment: Status and prospects

Remote-sensing and terrestrial measurements of the environment are reviewed, and some physical phenomena considered. Instrumental requirements are primarily in the microwave to millimeterwave and mid-infrared to optical spectral regions.Invited paper, presented at 14th IRMM Conference, Würzburg, 1989     

Mass spectra of some 1,2,4-triazine 1- and 2-oxides

A study of the fragmentation patterns of a variety of substituted 1,2,4-triazine 1- and 2-oxides has been undertaken. It is shown that the fragmentation patterns of the 1- and 2-oxides are extremely similar with the relative peak intensities varying with the type of substituents present.     

Ethylenimine derivatives of some 1,2,4-triazines

The first 3-ethylenimino-1,2,4-triazines ( 9 ) have been synthesized from the corresponding 3-(β-chloroethyl)amino-1,2,4-triazines ( 8 ). In addition some 2,3-dihydroimidazo[1,2-b]-1,2,4-triazines and imidazo[1,2-b]-1,2,4-triazines were obtained. The stability, properties and potential therapeutic value of these compounds are discussed.     

The synthesis of bisitaconamic acids and isomeric bisimide monomers

Members of a series of N,N′-alkylene bisitaconamic acids were synthesized from the reaction between itaconic anhydride and a homologous group of aliphatic diamines with the general formula H₂N (CH₂)_n NH₂, where n = 4–12. Cyclodehydration of the acids in toluene gave the isomeric imides: bisitaconimide, biscitraconimide, and citra-itaconimide. The isomeric imides were isolated, purified, and characterized for each diaminoalkane studied.     

Determination of titanium dioxide in foods using inductively coupled plasma optical emission spectrometry

Titanium dioxide is a common food additive of increasing interest in dietary intake studies and dietary exclusion studies. Food labelling for titanium dioxide is imprecise so a method was developed for its rapid determination in foods using acid digestion and inductively coupled plasma optical emission spectrometry (ICPOES). Twenty-five foods thought to contain titanium dioxide were obtained. Based on preliminary digestion studies, samples (500 mg) were digested in 18 mol l-1 H2SO4 at 250 degrees C for 1 h and then diluted to 5.9 mol l-1 H2SO4 before determination of titanium by ICPOES at 336.121 nm. Emission intensity was suppressed by H2SO4 so standards were matched for acid concentration. Titanium dioxide embedded in gelatine was used to assess accuracy. A standard reference material of known titanium concentration and six foods of known titanium dioxide content were used as external reference materials. Limits of detection were 2-7.5 ppb, depending on spectral integration times, and the signal was linear up to 5 ppm. Results for all control samples were in good agreement with the expected values. Twelve of the foods contained detectable titanium, ranging from 0.001 to 0.782% by weight, but only eight indicated this on their labels, four being exempt under food labelling regulations. Based on food portion sizes, an individual's daily intake of titanium dioxide could exceed 200 mg from just one of these products. This method may facilitate future studies on titanium dioxide intake, given the present limitations of food labelling.     

Practical asymmetric synthesis of a non-peptidic alphavbeta3 antagonist

The development of a practical and highly convergent synthesis of an alpha(v)beta3 antagonist is described. The two key fragments present in this compound, a tetrahydropyrido[2,3-b]azepine ring system and a chiral 3-aryl-5-oxopentanoic acid, were constructed independently and then coupled at a late stage using a Wittig reaction. The pyridoazepine moiety was prepared from N-Boc 6-chloro-2-aminopyridine via directed ortho-metalation/alkylation followed by in situ cyclization. A Suzuki reaction was then used to attach the propionaldehyde side-chain required for Wittig coupling. The coupling partner was prepared from asymmetric methanolysis of a 3-substituted glutaric anhydride followed by elaboration of the acid moiety to the requisite beta-keto phosphorane. Using this route, kilogram quantities of the desired drug candidate were prepared.