Chemical composition of heartwood and sapwood of Tectona grandis characterized by CG/MS-PY

Pyrolytic evaluation detected 85 compounds within the wooden, 51 within the sapwood and 61 within the heartwood (Desk 1). Acetic acid (10%) was probably the most ample compound within the sapwood adopted by oxiranemethanol (5.88%), phenol, 4-ethenyl-2-methoxy (7.71%), l propanoic acid, 2-oxo (5.51%), levoglucosan (4.47%), 1,2-cyclopentanedione (4.08%) and isoeugenol (4%), the opposite compounds representing lower than 3, 22% of the entire. Within the heartwood, probably the most ample compounds had been levoglucosan (26.65%), acetic acid (6.34%), cyclohexanecarboxaldehyde, 4-methoxy (5.1%), squalene (4 85%) and isoeugenol (3.65%) with lower than 2.97% for the others. Two and 4 sapwood and heartwood compounds, respectively, weren’t recognized. Acetic acid, the primary element of sapwood, can be utilized within the manufacture of inks, dyes, artificial silks, cellulose acetate and medicines.13whereas levoglucosan, the primary element with the heartwood, can be utilized within the manufacture of epoxy resins, pest management and pesticides14. Many compounds discovered are phenolic, these parts are elementary in resistance to assault by xylophagous brokers and can be utilized within the chemical and meals business.3.

Desk 1 Pyrolytic compound peak space (share of complete chromatogram space) of teak sapwood and heartwood.

The variety of compounds recognized within the sapwood and heartwood of 15-year-old teak wooden was decrease than that reported for this plant with a 70-year-old plant, with 127 compounds recognized, i.e. 74 and 71% within the sapwood and heartwood, respectively15. In Quercus spp. wooden, 40 totally different compounds had been discovered, acetic acid, levoglucosan, 3/2-furaldehyde and a pair of,3-dihydro-5-methylfuran-2-one had been the primary merchandise16. This can be attributable to age (15 and 70) and variations in pyrolysis temperature between these works. Compounds with the most important floor space are primarily derived from carbohydrates and are discovered within the preliminary a part of the pyrogram with a shorter retention time, and lignin and derived extracts within the center and on the finish of the pyrogram with a smaller floor space17. The ion-intensive mass spectra of lignin derivatives correspond, typically, to the bottom peak and compounds with carbohydrates are extra simply fragmented into smaller ones (besides levoglucosan) giving, generally, ions of low molecular weight and tough to determine. Some compounds recognized within the chromatogram are much like these obtained from teak wooden between 106 and 7015 years subjected to a thermochemical course of18.19. This similarity of some parts is because of the greater focus of parts (derived from lignin), that are extra steady when subjected to the thermochemical course of19.

The very best depth peak within the sapwood pyrogram (Fig. 1A) corresponds to acetic acid (peak 7), phenol, 4-ethenyl-2-methoxy (peak 43), isoeugenol (peak 50), 3′,5′-dimethoxyacetophenone (peak 54) and squalene (peak 85). Within the heartwood area (Fig. 1B), the best depth peak corresponded to acetic acid (peak 7), cyclohexanecarboxaldehyde, 4-methoxy (peak 26) and squalene (peak 85) . Most of those compounds, akin to acetic acid are derivatives of cellulose and hemicellulose, main parts of wooden, the degradation of lignins generate phenolic compounds, lastly, the extractives aren’t very consultant and are divided into a number of compounds , thus, their derivatives aren’t very consultant within the mass of the compounds evaluated16.

Determine 1
Figure 1

Py–GC/MS chromatogram of sapwood (A) and heartwood (B) of the Tectona grandis wooden.

The very best depth peak equivalent to acetic acid (peak 7), phenol, 4-ethenyl-2-methoxy (peak 43), isoeugenol (peak 50), 3′,5 ‘-dimethoxyacetophenone (peak 54) and squalene (peak 85) from lignin pyrolysis merchandise, that are extra ample and simpler to determine than carbohydrate derivatives15. Mass spectra with extra ample molecular ions are because of the better thermal stability of lignin fragrant compounds throughout pyrolysis and the influence of electrons from the mass spectrometer15. It’s simpler to determine merchandise derived from lignin as a result of its pyrolysis releases a combination of phenolic derivatives preserving the fragrant ring, with the unique methoxyl teams and half or all the propane facet chain20. Moreover, pyrolysis may cause a number of rearrangements in carbohydrates, leading to isomers that lack molecular ions and, subsequently, are tough to interpret.21.

Levoglucosan was the primary pyrolytic product shaped from the heartwood pattern (26.65%).

The formation of levoglucosan is because of the conversion of cellulose, hemicellulose, lignin and biomass extracts into sugar, acids and furans, compounds with bigger floor areasseven. Sugars can be utilized as a carbon supply, in fermentation, to provide compounds of commercial curiosity, akin to citric acid, ethanol, 5-hydroxymethylfurfural, furans, fragrant hydrocarbons and lipids22.23.

The compounds biphenyls (1,1′-biphenyl-3,4,4′-trimethoxy-6′-formyl) and anthraquinone, 2-methyl, of the naphthoatraquinone group had been recognized on the finish of the sapwood and wooden chromatogram of coronary heart (Fig. 1).

Identification of biphenyl (1,1′-biphenyl-3,4,4′-trimethoxy-6′-formyl) and anthraquinone, 2-methylated compounds of the naphthoatraquinone group, on the finish of the chromatogram for sapwood and heartwood are because of the problem of fragmentation into small parts and since they’re derivatives of lignin. This compound, throughout pyrolysis, releases a combination of phenolic derivatives preserving the fragrant ring, with the unique methoxyl teams, and half, and even all, of the propane facet chain.20. These parts, with antifungal and bactericidal properties, shield the plant towards xylophagous organisms, rising the sturdiness of its wooden.24.25. As well as, anthraquinones can change artificial dyes26,27.28.

Syringyl/guaiacyl ratio

The syringyl/guaiacyl (S/G) ratio was 0.51 ± 0.010 and 0.50 ± 0.012 for sapwood and heartwood respectively. 4-vinylsyringol, trans-coniferyl alcohol and coniferaldehyde, 4-vinylguaiacol, 4-methylguaiacol, vanillin and sinapinaldehyde had been the primary compounds derived from lignin.

The S/G ratio of T. grandis heartwood and sapwood was decrease than that of 70-year-old teak wooden from the DBH place, 0.8 for heartwood and sapwood with a complete lignin content material of 35.4% for the sapwood and 37.3% heartwood15 and for 12 yr previous teak with a complete lignin content material of 31% and an S/G ratio of 0.7229 and of Eucalyptus spp. used for the manufacturing of kraft pulp, with an S/G of two.0 to three.230. Variations in S/G ratio values ​​could also be attributable to development stage (age), climatic elements, and publicity to microorganisms, bugs, and pests31. The S/G ratio is essential for the pulp business as a result of alkaline hydrolysis reactions of lignin fragmentation range with the ratio of syringyl models29. The chemical construction of syringyl lignin is much less condensed and extra favorable to delignification by Kraft cooking liquor because of the lack of C5 reactive carbon obtainable for response within the polymerization step of lignin biosynthesis32. As well as, the excessive content material of guaiacyl models signifies a extra condensed lignin (better variety of bonds between C–C models), rising the thermal resistance of the wooden.31. Characterization of lignin by pyrolysis (Py-GC/MS) is an environment friendly, sooner and cheaper technique with greater reagent consumption, evaluation time and accuracy in comparison with conventional strategies12.

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