Significant Lability of Guaiacylglycerol β-Phenacyl Ether under Alkaline Conditions
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- 作者：Aiko Imai ; Tomoya Yokoyama ; Yuji Matsumoto ; Gyosuke Meshitsuka
- 刊名：Journal of Agricultural and Food Chemistry
- 出版年：2007
- 出版时间：October 31, 2007
- 年：2007
- 卷：55
- 期：22
- 页码：9043 - 9046
- 全文大小：132K
- 年卷期：v.55,no.22(October 31, 2007)
- ISSN：1520-5118
文摘
It was observed that the β-O-4 bond cleavage of a dimeric phenolic lignin model compound with an α-carbonyl group at the B-ring, 2-(2-ethoxy-4-formylphenoxy)-1-(4-hydroxy-3-methoxyphenyl)propane-1,3-diol (I), is extremely fast in a mild anaerobic alkaline treatment (0.45 mol/L NaOH, 95 °C, 0.8 MPa of N2). This phenomenon significantly contrasts with the case of a common dimeric phenolic lignin model compound without any specific functional group, 1-(4-hydroxy-3-methoxyphenyl)-2-(2-methoxyphenoxy)propane-1,3-diol (II). The most plausible mechanism is the migration of the B-ring from the β- to the α-position following the SNAr mechanism. Because this migration affords the alkaline labile phenolic α-O-4-type compound (XI), the formation of the quinone methide as well as the cleavage of the originally alkaline very stable alkyl-aryl ether bond is promoted. This promotion of the quinone methide formation explains why a relatively large amount of 4-hydroxy-3-methoxybenzaldehyde (IV) is produced from I in an oxygen–alkali treatment.