J. Szammer

A new method for the preparation of carboxyl-labelled aliphatic carboxylic acids

Abstract The exchange reaction of carboxyl groups with labelled carbon dioxide has been investigated and shown to provide an excellent method for the preparation of labelled aliphatic carboxylic acids.

Kinetics and mechanism of the oxidation of ketones with permanganate ions

The kinetics and mechanism of the oxidation of ketones with permanganate ions were studied in aqueous acidic and alkaline media for acetone, hydroxyacetone, butan-2-one and butane-2,3-dione. Acid catalysed nucleophilic addition of the permanganate to the carbonyl C-atom is suggested. In alkaline media, parallel with electron abstraction from the enolate, a concerted mechanism is proposed. Intermediates and end products were determined. Comparisons between halogenation and oxidation have been made.

Study on the production of formaldehyde-14C by direct reduction of14CO2 with LiAlH4

A vial technique was developed for the synthesis of formaldehyde-14C from14CO2 in an ether solution of lithium aluminium hydride. The yield of formaldehyde (40–50%) was achieved by optimization of the reaction parameters.

The mechanism of hydrogen atom abstraction from phenols involved in hydrogen bonding with ester carbonyl groups

Rate constants have been determined in different solvents for hydrogen atom abstraction from alkyl-substituted phenols and deuteriated analogues by polyvinyl acetate radical (R˙). The following solvents were used: ethyl acetate, ethyl [2H3]acetate, ethyl pivalate, ethyl trifluoroacetate, acetone, [2H6]acetone, dimethyl sulphoxide. The reactivity of the phenols and the primary kinetic deuterium isotope effect (p.k.i.e.) demonstrate a strong solvent dependence exhibiting the highest values in ethyl trifluoroacetate (p.k.i.e. 57 ± 23 for 2,4,6-trimethylphenol at 50 °C). Incorporation of CH314COOCH2CH3 and (CH3)3C14COOCH2CH3 into polyvinyl acetate increases in the presence of phenols. These facts conclusively prove that hydrogen atom abstraction proceeds within the hydrogen bond to the radical formed by addition of R˙ to the ester carbonyl hydrogen bonded to phenol.

Synthesis of Deramciclane labelled with radiocarbon in various positions

[U- 14 C]Bromobenzene, prepared from [ 14 C]barium carbonate according to literature procedures, was transformed (Li / diethylether) into [ 14 C]phenyllithium which was condensed with camphor giving rise to [U- 14 C-phenyl]borneol: 2 . The latter, after conversion into its sodium salt, was reacted with dimethylaminoethyl chloride to give [ 14 C-Ar]Deramciclane, which was isolated as the fumarate salt. This 8 step synthesis from [ 14 C]BaCO 3 gave an overall yield of 12 %. [1- 14 C]Sodium acetate, through a standard 5 step literature procedure, was converted to N,N-dimethylaminoethyl-1- 14 C chloride 5 which was condensed with the sodium derivative of 2-phenylborneol giving rise to [1- 14 C-side chain]Deramciclane, again isolated as the fumarate. This 6 step synthesis from [ 14 C]BaCO 3 gave an overall yield of 8 %. The specific radioactivities from the two syntheses were respectively 40 mCi/mmol and 21 mCi/mmol; chemical and radiochemical purities were better than 98 %.

Catalysis of thermal exchange reactions between carboxyl groups and14CO2

The rate of thermal exchange reactions between carboxyl groups and14CO2 increases in the presence of catalytic amounts of alkali malonates. This catalytic effect can be utilized for preparative purposes also in the synthesis of11C-labelled aliphatic carboxylic acids from11CO2.