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Salts of 4-hydroxypyrimidine and several 2-substituted 4-hydroxypyrimidines were treated with alkyl halides under a variety of reaction conditions. In cation-solvating media, methylation occurred mainly at N-3. Increased N-l methylation was observed in hydrogen-bonding solvents and solvents of lower dielectric constant. Studies in dimethylf ormamide revealed significant steric influences. When the alkyl halide was varied from methyl to ethyl to isopropyl or when the group on the 2 position was varied from hydrogen to methyl to ethyl, alkylation at oxygen increased at the expense of alkylation at N-3. 2-Trifluoromethyl-4-hydroxypyrimidine in dimethylf ormamide reacted with alkyl halides to give mainly 4-alkoxy-2-trifluoromethylpyrimidines.

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Material balance studies were performed on 85 mm machine-made cigarettes containing 1.5 % unlabelled PMO [3-phenyl-5-methyl-1,2,4-oxadiazole], which were smoked under standard conditions to a 23 mm butt length. Using standard analytical techniques, relative distributions of PMO of approximately 28 % for mainstream, 22 % for sidestream, and 27 % for butt were obtained, with an overall recovery of unchanged PMO of 75-80 %. Radiocarbon labeled PMO [5-14C] cigarettes were prepared manually (70 mm, 2 % PMO) and smoked under standard conditions to a 20 mm butt length. Four smoking runs gave statistically valid data accounting for 95.99 ± 0.58 % of the original label. Measurements of the radioactivity were made by liquid scintillation counting of the various fractions. The mainstream smoke passing through a Cambridge filter pad contained less than one percent of the label as carbon dioxide, and no volatile organic compounds. The PMO undergoing decomposition gave rise to products found almost entirely in the sidestream.