Nisbah stereoisomer erythro dan threo struktur β -o-4 serta hubungannya dengan jenis cincin aromatik penyusun makromolekul lignin

Abstract

Reaction woods were obtained from leaning wood stems of several wood species and the relationships between the type of reaction wood and lignin characteristics was observed. As lignin characteristics, stereo structure of β-O-4 linkage (erythro/threo ratio), aromatic ring type (syringyl/guaiacyl ratio), klason lignin yield and acid soluble lignin content were determined. The relationships could be classified as a typical gymnosperms and angiosperms. Gymnosperms species formed compression wood having high lignin content as well as erythro/threo ratio. However, angiosperms species produced tension wood which tend to have lower lignin content but higher erythro/threo and syringyl/guaiacyl ratio. In all types of reaction wood, erythro/threo ratio changed with clear tendency from the opposite wood part to reaction wood part, but the direction of the change was dependent on its type. In Guaiacyl-Syringyl lignin, erythro/threo ratio was highly correlated with syringyl ratio, and in Guaiacyl-lignin, it was correlated with p-hydroxyphenyl content although the range of variation was very small. In addition, syringyl/guaiacyl rasio was also correlated with acid-soluble lignin formation.

Karakteristik kimia lignin beberapa jenis kayu dan hubungannya dengan pembentukan kayu reaksi telah diteliti yang meliputi stereokimia erythro dan threo dari struktur β-O-4 (rasio erythro/threo); jenis cincin aromatik penyusun lignin (rasio siringil/guaiasil), lignin klason, dan lignin terlarut asam. Karakteristik kimia lignin kayu reaksi dapat dibedakan berdasarkan jenis kayu gimpospermae dan angiospermae. Jenis kayu kelompok gimnospermae membentuk kayu reaksi tekan dengan kadar lignin yang lebih tinggi yang diikuti tingginya rasio erythro/threo struktur β-O-4, sedangkan jenis kayu kelompok angiospermae membentuk kayu reaksi tarik yang memiliki kadar lignin lebih rendah dengan rasio erythro/threo dan siringil/guaiasil yang tinggi. Pada semua tipe kayu reaksi, rasio erythro/threo berubah secara bertahap dari bagian kayu oposit ke arah bagian kayu reaksi, akan tetapi perubahannya tergantung dari tipe kayu reaksinya. Pada jenis lignin guaiasilsiringil, rasio erythro/threo berkorelasi dengan rasio siringil/giaiasil, sedangkan pada lignin guaiasil berkorelasi dengan kadar unit p-hidroksiphenil. Rasio siringil/guaiasil juga berkorelasi dengan pembentukan lignin terlarut asam.