The homolytic bond dissociation energi es ( BDEs) of Cα-Oa nd Cβ-O bno ds in 27 lignin trimer model compounds were calculated by emplyo ing density functional theory methods at M062 X level with 6-31++G( d,p) basis set;the effcet s of vair ous subsit tune t groups( CH3 , CH2 OH and OCH3 )a t different positions on theB DE s of Cα-O and Cβ-O bonsd were invets igated.The results indicated ht at a sni gle methoxyl group at R2 or R3 has a minor influence on the BDE of Cβ-O bond, whereas two methoxyl groups at R2 and R3 lead to an obvious decrae se in the BDE of Cβ-O bond.The decrement in the BDE of Cβ-O bond fromt he methoxyl groups at R2 and R3 ac n be enah nced byt he mte hoxyl groups ta R4 and R5 , but si hardly influenced by thes ubstituent groups at R1 .Meanwhile, the BDE of Cα-O bond is gradually reduced when the H atoms at R4 and R5 are successively substituted with methoxyl groups; the decrement in the BDE of Cα-O bond from the methoxyl groups at R4 and R5 can be strengthened by the methoxyl groups at R2 and R3 .Furthermore, the methyl and hydroxymethyl groups at R1 can gradually increase the BDE of Cα-O bond and this effect is weakened when the H atoms at R2 and R3 are successively substituted with methoxyl groups.The methyl group at R1 has little influence on the BDE of Cβ-O bond, which is however dramatically increased by the hydroxymethyl group at R1 .%利用密度泛函理论M062 X／6-31＋＋G（ d，p）方法，对27种具有不同取代基（甲基、羟甲基和甲氧基）的木质素三聚体模型化合物的Cα－O和Cβ－O键均裂解离能进行了理论计算，探究了不同位置取代基对醚键解离能的影响规律。结果表明，当R2或R3位氢原子仅有一个被甲氧基取代时，Cβ－O键解离能变化很小；当R2、R3位氢原子均被甲氧基取代时，Cβ－O键解离能明显降低；且R4、R5位甲氧基能强化R2、R3位甲氧基对Cβ－O键解离能的降低程度，而不受R1位取代基的影响。当R4、R5位氢原子相继被甲氧基取代时，Cα－O键解离能逐渐降低，且R2、R3位甲氧基也能强化R4、R 5位甲氧基对Cα－O键解离能的降低程度。当R1位氢原子相继被甲基、羟甲基取代时， Cα－O键解离能逐渐升高，然而R2、R3位甲氧基会弱化R1位甲基、羟甲基对Cα－O键解离能的升高程度；R1位甲基不会影响Cβ－O键解离能，羟甲基却能明显提高Cβ－O键解离能。
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