Activation parameters and location of the transition state in the retro-Diels-Alder reaction of a 7-oxabicylo[2.2.1]hept-5-ene derivative

Abstract

l-Chloro-2-(JV-chIoro-p-toluenesulfonamido)acenaphthene. To a well-stirred cold (0-2 °C) solution of 2.01 g of acenaphthylene in 15 mL of CH2C12 was added dropwise (10 min) a solution of 3.2 g of Cl2NTs in 15 mL of CH2C12. Workup as described above followed except that CC14 at -30 °C was used in place of ether at 0-2 °C to triturate the crude solid. The insoluble portion (0.9 g, mp 149-152 °C) was identified as 1chloro-2-p-toluenesulfonamidoacenaphthene (see below). The CC14 filtrate was evaporated and the residue was triturated with 15 mL of ether. Cooling to -30 °C (dry ice-acetone bath) gave a light-yellow solid, which was washed with two 3-mL portions of cold (-20 °C) ether to give 2.1 g (59.2%) of the N-chloro compound, mp 115-117 °C. The analytical sample had the following: mp 117-119 °C (ether); IR (CHC13) 1340, 1160 cm-1 (S02);

Thermal Breakdown by the Retro Diels–Alder Reaction of Crosslinking in Poly[styrene‐co‐(furfuryl methacrylate)]

“…A plot of ln k versus 1/ T according to the Arrhenius equation (Figure 3) yielded 21 kJ · mol −1 as the activation energy ( E a ). Values ranging from 41 to 161 kJ · mol −1 for E a have been reported for retro D‐A processes in which pairs of diene/dienophile molecules different from those in our system are involved 6,8,9,12,19,20. However, no values of E a have been found for the retro D‐A reaction taking place within a crosslinked polymer system.…”

The Effect of Pressure on Organic Reactions

“…This surprising result could be confirmed by three independent studies. In the two earlier studies G. Jenner et al and N. S. Isaacs et al found the ratio ∆V ≠ /∆V in the Diels-Alder reaction of furan with acrylonitrile [23] and that of N-benzoylpyrrole with N-phenylmaleic imide [24] to be larger than unity (Φ = 1.06 and 1.37, respectively). The cycloadducts isolated from both reactions Table 1 Molar volumes, V, van der Waals Volumes, V W , and packing coefficients, η, calculated for acyclic and cyclic ground and transition structures needed for the explanation of the pressure effect on the Diels-Alder reaction of 1,3-butadiene with ethene.…”

High-Pressure Influence on the Rate of Diels-Alder Cycloaddition Reactions of Maleic Anhydride with Some Dienes

“…Very large variations of the ratio V = / V r-n (from 1.0 to 1.69) were observed in the reaction of 1 with trans-1-methoxybutadiene in different solvents [29]. There is a direct experimental validation of the acceleration of some retro-Diels-Alder reactions under elevated pressure [2][3][4][5].…”