𝔖 Bobbio Scriptorium
✦   LIBER   ✦

Bimolecular Formation of Radicals by Hydrogen Transfer, 12. – Transfer hydrogenation ofp-Substituted α-Methylstyrenes and of 9-Methylenefluorene as a Criterion of Mechanism

✍ Scribed by Friebolin, Heike ;Roers, Rolf ;Ebenhoch, Jochen ;Gerst, Matthias ;Rüchardt, Christoph

Publisher
John Wiley and Sons
Year
1997
Tongue
English
Weight
513 KB
Volume
1997
Category
Article
ISSN
0947-3440

No coin nor oath required. For personal study only.

✦ Synopsis

Abstract

The uncatalyzed transfer hydrogenation of substituted α‐methylstyrenes with 9,10‐dihydroanthracene (DHA), xanthene (XAN), or 9,10‐dihydroacridine (DHAC) was studied mechanistically. The three hydrogen donors react at very similar rates and with similar activation parameters and with little discrimination between the various substituted styrenes. The kinetic isotope effects are also similar and the solvent effect is small. A hydrogen atom transfer mechanism (retrodisproportionation) is, therefore, preferred to a hydride transfer mechanism. This is supported by the very similar reactivity of the hydrogen transfer reaction of DHA and XAN with 9‐methylenefluorene. The product yields in all reactions investigated in this project were >90%.

📜 SIMILAR VOLUMES

Bimolecular formation of radicals by hyd
Bimolecular formation of radicals by hydrogen transfer, 9. Uncatalyzed transfer hydrogenation of α-methylstyrene by 9,10-dihydroacridine andN-methyl-9,10-dihydroacridine
✍ Friebolin, Heike ;Rüchardt, Christoph 📂 Article 📅 1995 🏛 John Wiley and Sons 🌐 English ⚖ 305 KB

## Abstract Hydrogen is transferred from acridane (1c) and __N__‐methylacridane (1d) to α‐methyl‐styrene (2) in a bimolecular uncatalyzed reaction at 260–300°C. On the basis of the activation parameters (for 1c: Δ__H__^≠^ = 29.0 kcal/mol, Δ__S__^≠^ = −23.5 e.u. in triglyme) the kinetic isotope effe