Propargylation of arabinogalactan with propargyl halides¡ªa facile route to new functionalized biopolymers

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• 作者：Lyudmila A. Grischenko ; Lidiya N. Parshina ; Lyudmila V. Kanitskaya ; Lyudmila I. Larina ; Lyubov N. Novikova ; Boris A. Trofimov
• 关键词：Arabinogalactan functionalization ; Biopolymers ; Propargyl ethers ; Phase transfer catalysis
• 刊名：Carbohydrate Research
• 出版年：2013
• 出版时间：19 July, 2013
• 年：2013
• 卷：376
• 期：Complete
• 页码：7-14
• 全文大小：891 K

文摘

New arabinogalactan propargyl ethers with degree of substitution (DS) up to 2.8 have been obtained by propargylation of arabino-3,6-galactan (AG) with propargyl bromide (PB) in the two-phase system 30-60 % §¬§°§¯ aqueous solution/toluene in the presence of triethylbenzylammonium chloride (TEBA§³) or without catalyst (ambient temperature, 1-24 h) in 20-87 % yields. The highest yields have been reached using TEBA§³ as phase-transfer catalyst, though the non-catalytic version proves to be also efficient (DS 2.8, 70 % yield). The propargylation of AG is less effective in the systems M§°§¯ (M = Na, K)/DMSO. DS of propargyl AG reaches 1.8 (70 % yield) when propargyl chloride is used as propargylating agent, while with PB under the same conditions DS value does not exceed 0.4-0.6, the yields being 44-65 % . Under the action of t-BuOK/DMSO system, the AG propargyl ethers have been isomerized to the corresponding unstable allenyl ethers. AG propargyl ethers with DS 2.0 have been almost exhaustively metallated with Ag₂O/NH₃ system to give AG-Ag acetylides derivatives with Ag/CC ratio equaling 0.95.