Domenico Spinelli

Ring–Ring Interconversions of Nitrosoimidazoles. The Effect of some Condensed Six-Membered Rings on the Reactivity

Abstract The study of the effect of a condensed ring on the reactivity of nitrosoimidazoles with hydrochloric acid has been extended to some six-membered rings: thus, the reactivity of 2-(4-chlorophenyl)-3-nitrosoimidazo[1,2-a]pyridine (6), 6-chloro-2-(4-chlorophenyl)-3-nitrosoimidazo[1,2-b]pyridazine (7), 2-(4-chlorophenyl)-3-nitrosoimidazo[1,2-a]pyrimidine (8a) and 2-(4-chlorophenyl)-3-nitrosoimidazo[1,2-a]pyrazine (9) has been examined. The striking differences observed in the reactivity of compounds 6–9 (denitrosation, ring-opening with ammonia elimination, ring–ring interconversion with the unexpected loss of a C3 fragment and decomposition, respectively) have been discussed.

Formation of micelles and liposomes from carnitine amphiphiles

Esterification of the carboxy and/or the hydroxy groups of (R)-carnitine (3-hydroxy-4-trimethylammonium butanoate) produces interesting classes of (cationic or zwitterionic) surfactants whose CMC values are in general predictable from their molecular structure. In fact similar relationships between CMC and the number of carbon atoms, Cn, have been found for three classes of such surfactants. However the sensitivity of CMC to Cn for the diesters is considerably lower than that calculated from literature values for the monoesters (either in their cationic or zwitterionic forms). The CMC values for the diesters have been determined by tensiometric, conductimetric and spectrophotometric methods, both in pure water and in 0.154 M NaCl solutions, at 25 degrees C. In particular the tensiometric results provide evidence that double-chain diesters undergo self assembly into structures more complex than simple micelles if the two chains are of comparable length. EPR and electron microscopy experiments show that the aggregates spontaneously formed by these surfactants are a mixture of multilamellar vescicles.

Kinetics of anilinodechlorination of 3-bromo- and 3-methoxy-2-thenoyl chlorides in benzene

The susceptibility constants measured for the reaction of 3-bromo-(Ia) and 3-methoxy-2-thenoyl (Ic) chlorides with some meta- and para-substituted anilines in benzene at 25°C have confirmed the occurrence of two different mechanisms for the anilinodechlorination of 3-substituted 2-thenoyl chlorides: (i) the classical AE mechanism and (ii) the IP mechanism (unusual for reactions with anilines in nonpolar aprotic solvents) which can operate when electron-releasing substituents are present in the thiophen ring.

Meisenheimer-type adducts from thiophene derivatives. Part 6. A kinetic and thermodynamic study of substituent effects on the formation of some non-gem adducts

The rate and equilibrium constants for the formation of the Meisenheimer-type adducts [(6) and (8)] from some 4-nitro-2-X-(5) or some 2-nitro-4-X-thiophenes (7) and sodium methoxide have been measured at 25 °C in methanol or methanol–dimethyl suiphoxide mixtures. The observed stability and reactivity patterns have been interpreted in the light of the hyper-ortho relation in the thiophene ring and the special ability of the nitro group to stabilize effectively the adducts from a para-like position also.