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

ABSTRACT

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 (V_cr) and in solutions (V_S) were determined. The reaction volume due to the reorganization of the bonds (Δ_r-n V_W) is nearly the same as in solid state (Δ_r-n V_cr) and both values are only about 30% from the reaction volume in solution (Δ_r-n V_S). 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.

KEYWORDS:

• High pressure
• Diels–Alder reaction
• reaction volume
• compressibility coefficient

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Russian Science Foundation(Project No. 19-73-10131), the Ministry of Education and Science of Russian Federation (Project No. 4.6223.2017/9.10), and the research grant of Kazan Federal University.