Cross-dimerization of α-methylstyrene with isoamylene and aldol condensation of cyclohexanone using a cation-exchange resin and acid-treated clay catalysts

1,4-Dithianes: attractive C2-building blocks for the synthesis of complex molecular architectures

This review covers the synthetic applications of 1,4-dithianes, as well as derivatives thereof at various oxidation states. The selected examples show how the specific heterocyclic reactivity can be harnessed for the controlled synthesis of carbon-carbon bonds. The reactivity is compared to and put into context with more common synthetic building blocks, such as 1,3-dithianes and (hetero)aromatic building blocks. 1,4-Dithianes have as yet not been investigated to the same extent as their well-known 1,3-dithiane counterparts, but they do offer attractive transformations that can find good use in the assembly of a wide array of complex molecular architectures, ranging from lipids and carbohydrates to various carbocyclic scaffolds. This versatility arises from the possibility to chemoselectively cleave or reduce the sulfur-heterocycle to reveal a versatile C2-synthon.

Esterification of fatty acid over Tunisian acid activated clay: kinetic study

Tunisian acid activated clay was investigated as catalyst in the esterification of stearic acid with ethyl alcohol, carried out in a semi-continuous reactor. Kinetic study shows that the reaction is first order with respect to acid concentration. The activation energy found was 21 kJ/mol. This result suggests that the reaction process was controlled by a diffusional step. A kinetic model, giving the apparent constant rate as a function of temperature and catalyst concentration, has been established. This equation has been then successfully applied for a complex mixture of fatty acid.