No abstract

The kinetics of the Diels-Alder condensation of maleic anhydride with 1,3-butadiene has been measured in seven solvents at 25.00"C using a vapour-pressure technique. The rate constants are used in conjunction with activity coefficient data to find the relative activity in solution of the transition state from the Brransted-Bjerrum equation. These results show that the transition state resembles electronically the reactants rather than the product, and permit comment on the reaction mechanism and on the prediction of solvent effects for Diels-Alder reactions.Transition state theory provides a powerful tool for visualizing the molecular details of a chemical reaction in terms of thermodynamic functions. For example, the rate constant k (relative to its value in an ideal solution ko) for a bimolecular reaction of A and B, through a transition state M, is given in terms of thermodynamic activity coefficientsIn (klko) = In (YAYBlYM).(1) Although the properties of the transition state are not directly available experimentally, they can be obtained from the application of eqn (1). Such information can then prove useful for many purposes, such as for the interpretation of reaction mechanisms or for solvent Arnett and McKelvey have applied the transition state theory in a detailed study of the activation parameters for some solvolysis reactions in aqueous mixtures.In this work is reported the kinetics of the simple, bimolecular Diels-Alder condensation of maleic anhydride (A) and 1,3-butadiene (B) to form the product (P), cis-4-cyclohexene-1 ,Zdicarboxylic anhydride.This reaction has been carried out in seven solvents at 25°C using a vapour-pressure technique. The results are compared with measurements of activity of A, B and P in solutions as obtained from vapour pressure, solubility, and differential boiling point *Then the information about the solvent-solute interactions of the transition state as found from eqn (1) permits examination of the reaction mechanism as well as indicating an approach for solvent design for Diels-Alder react ions.

was used without further purification, since it had a melting point of 2.5°± 0.1°C ., which was in good agreement with the literature value of 2.55°C. (5).A known excess of salt was added to a selected mixture of water and formamide in a 100-ml. volumetric flask. Each flask was attached to the arm of a mechanical shaker and immersed in a water bath which was maintained at 25°C.

No abstract

New values of the dipole moments of maleic anhydride and three of its Diels-Alder adducts have been determined using the technique of Guggenheim. The results are compared with the dipole moments of several other cyclic anhydrides.