High pressure influence on the Diels–Alder reaction volume in the solid phase at pressure up to 7000 bar and in solution

Abstract

© 2019, © 2019 Informa UK Limited, trading as Taylor & Francis Group. The molar volumes of tetracyanoethylene (1), maleic anhydride (2), N-phenylmaleimide (3), anthracene (4), trans, trans-1,4-diphenyl-1,3-butadiene (5), and their Diels–Alder reaction adducts (6 -9) in the solid state (Vcr) and in solutions (VS) were determined. The reaction volume due to the reorganization of the bonds (Δr-n VW) is nearly the same as in solid state (Δr-n Vcr) and both values are only about 30% from the reaction volume in solution (Δr-n VS). The compressibility coefficients of crystals 2 (12.1·10−6) and 4 (12.0·10−6) are the same and larger than that of adduct 7 (9.45·10−6 bar−1). A huge difference is shown in the magnitudes of the reaction volumes in the solid state and in solutions. It was found that after compressing the reagent powders to 5–8 kbar and depressurizing, these crystals have a density very close to the density of single crystals.