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首页> 外文期刊>RSC Advances >Selective production of bio-based aromatics by aerobic oxidation of native soft wood lignin in tetrabutylammonium hydroxide
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Selective production of bio-based aromatics by aerobic oxidation of native soft wood lignin in tetrabutylammonium hydroxide

机译：用四丁基氢氧化铵在氢氧化铵的天然软木木质素的有氧氧化选择性生产生物氧化剂

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Aerobic oxidation of native soft wood lignin in an aqueous solution of Bu _(4) NOH facilitates efficient production of vanillin (4-hydroxy-3-methoxybenzaldehyde), which is one of the platform chemicals in industry. Oxidation of Japanese cedar ( Cryptomeria japonica ) wood flour at 120 °C for 4 h under O _(2) in Bu _(4) NOH-based aqueous solutions produced vanillin in 23.2 wt% yield based on the Klason lignin content of the starting material. This yield was comparable to that in alkaline nitrobenzene oxidation of the same material (27.2%), which indicated that our aerobic oxidation exploited the full potential of the wood flour for vanillin production. Further mechanical investigation with lignin model compounds suggested that the vanillin formation occurred mainly through following successive reactions: alkaline-catalyzed degradation of β-ether linkages in middle units of lignin polymer to form a glycerol end group, oxidation of the glycerol end group by O _(2) to a HC _(α) O moiety, and release of vanillin from the HC _(α) O end. One of the reasons for the high performance of Bu _(4) NOH for the vanillin production was explained by the general understanding in organic chemistry that Bu _(4) OH is a stronger base than simple alkali, e.g. NaOH. The other more fundamental mechanical aspect was that Bu _(4) N ~(+) suppressed disproportionation of the vanillin precursor (the C _(α) HO end group) probably due to strong interaction between the cation and the HC _(α) O end group.
机译：Bu _（4）NOH水溶液中天然软木木质素的有氧氧化促进了Vanillin（4-羟基-3-甲氧基苯甲醛）的有效生产，这是工业的平台化学品之一。日本雪松（Cryptomeria japonica）木粉在120℃下在Bu _（2）的40℃下的木粉在Bu _（4）NOH基水溶液中产生的香草蛋白，其基于启动的Klason木质素含量为23.2wt％产率。材料。该产率与相同材料的碱性硝基苯氧化（27.2％）相当，这表明我们的好氧氧化利用木粉用于香草醛生产的全部潜力。与木质素模型化合物的进一步机械调查表明，Vanillin形成主要通过连续反应来发生：碱性催化在木质素聚合物中间单元中β-醚键的降解，形成甘油终基，甘油末端组的氧化通过O _ （2）至HC _（α）O部分，从HC _（α）O结束的香草素释放。通过在有机化学中的一般性理解中解释了Vanillin生产的高性能的原因之一，即Bu _（4）oh是比简单的碱的较强的基础，例如碱基。 naoh。另一个基本的机械方面是Bu _（4）n〜（+）抑制了香草蛋白前体的歧化（C _（α）Ho端组）可能是由于阳离子和HC _（α）之间的强相互作用o结束组。

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