27890-67-1Relevant articles and documents
Photocondensation of o-Hydroxybenzyl Alcohol in an Alkaline Medium: Synthesis of Phenol-Formaldehyde Resins
Wan, Peter,Hennig, Darren
, p. 939 - 941 (1987)
A new method for the synthesis of phenol-formaldehyde (Bakelite) resins via a new photochemical reaction, the photocondensation of o-hydroxybenzyl alcohol (saligenin) in an alkaline medium, is reported.
o-Quinone methide as a common intermediate in the pyrolysis of o-hydroxybenzyl alcohol, chroman and 1,4-benzodioxin
Dorrestijn, Edwin,Epema, Onno J.,Van Scheppingen, Wibo B.,Mulder, Peter
, p. 1173 - 1178 (1998)
The product composition in the very low pressure pyrolysis (550-1210 K) of o-hydroxybenzyl alcohol (HBA), 3,4-dihydro-2H-1-benzopyran (chroman), and 1,4-benzodioxin (BD) indicates that o-quinone methide (o-QM) is the common intermediate in each case. At complete conversion of HBA, o-QM was observed as the only product and the mass spectrum of o-QM could be obtained. At higher temperatures (>950 K), o-QM is subsequently converted into benzene and CO. The thermolysis process for chroman starts with cleavage of the phenoxy-carbon bond and proceeds with ethene elimination, yielding o-QM. The high pressure rate parameters for unimolecular decay have been determined to obey kchroman/s-1 = 1015.3 exp (-269/RT). For BD only the cleavage of the phenyl-vinoxy bond has been observed, and after rearrangement and CO elimination o-QM is formed. The Arrhenius equation for the overall rate of disappearance has been found as kBD/s-1 = 1015.6 exp (-310/RT). Ultimately (1100 K) the thermolysis of BD leads to 1 mole of benzene and 2 moles of CO.
Contrasting Photolytic and Thermal Decomposition of Phenyl Azidoformate: The Curtius Rearrangement Versus Intramolecular C-H Amination
Wan, Huabin,Xu, Jian,Liu, Qian,Li, Hongmin,Lu, Yan,Abe, Manabu,Zeng, Xiaoqing
, p. 8604 - 8613 (2017/11/24)
The decomposition of phenyl azidoformate, PhOC(O)N3, was studied by combining matrix isolation spectroscopy and quantum chemical calculations. Upon UV laser photolysis (193 and 266 nm), the azide isolated in cryogenic noble gas matrices (Ne and Ar, 2.8 K) decomposes into N2 and a novel oxycarbonylnitrene PhOC(O)N, which was identified by matrix-isolation IR spectroscopy (with 15N labeling) and EPR spectroscopy (|D/hc| = 1.620 cm-1 and |E/hc| = 0.024 cm-1). Subsequent visible-light irradiation (532 nm) causes rearrangement of the nitrene into phenoxy isocyanate PhONCO with complex secondary fragmentation (PhO· + ·NCO) and radical recombination species in matrices. The observation of PhONCO provides solid evidence for the Curtius rearrangement of phenyl azidoformate. In sharp contrast, flash vacuum pyrolysis (FVP) of PhOC(O)N3 at 550 K yields N2 and exclusively the intramolecular C-H amination product 3H-benzooxazol-2-one. FVP at higher temperature (700 K) leads to further dissociation into CO2, HNCO, and ring-contraction products. To account for the very different photolytic and thermal decomposition products, the underlying mechanisms for the Curtius rearrangement (concerted and stepwise) of PhOC(O)N3 and the intramolecular C-H amination of the nitrene in both singlet and triplet states are discussed with the aid of quantum chemical calculations using the B3LYP, CBS-QB3, and CASPT2 methods.
Generation and application of o-Quinone methides bearing various substituents on the benzene ring
Sugimoto, Hiromichi,Nakamura, Satoshi,Ohwada, Tomohiko
, p. 669 - 679 (2008/02/09)
o-Quinone methides (o-QMs) are highly reactive, short-lived intermediates, which have potential synthetic applicability. However, few studies on the generation of o-QMs bearing an electron-withdrawing group have been reported. Herein we present a general method for the generation of o-QMs, particularly those substituted with an 0lectrophilic substituent, from new precursors, 4H-1,2-benzoxazines 2. We have also studied systematically the Diels-Alder reactions of o-QMs with various dienophiles, such as vinyl ethers, enamines and imines. The reactions provide a versatile route to substituted chromans, phenols and 3,4-dihydro-2H-benzo[e]-[1,3]oxazines (3,4-dihydro-1,3-benzoxazines). Furthermore, we applied the new method to the derivatization of some natural products.
