scholarly journals Revealing Structural Modifications of Lignin in Acidic γ-Valerolactone-H2O Pretreatment

Polymers ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 116
Author(s):  
Suxiang Li ◽  
Chengke Zhao ◽  
Fengxia Yue ◽  
Fachuang Lu
Keyword(s):  
Structural Changes ◽  
Solvent System ◽  
Side Chain ◽  
Solvent Mixtures ◽  
Aryl Ether ◽  
Structural Modifications ◽  
System A ◽  
Nmr Characterization ◽  
Lignin Model

γ-valerolactone (GVL)/H2O/acid solvent mixtures has been used in chemical pretreatment of lignocellulosic biomass, it was claimed that GVL lignins were structurally close to proto (native) lignins, or having low molecular weight with narrow polydispersity, however, the structural changes of GVL lignins have not been investigated. In this study, β-O-4 (β-aryl ether, GG), β-5 (phenylcoumaran), and β-β (resinol) lignin model compounds were treated by an acidic GVL-H2O solvent system, a promising pretreatment of lignocellulose for biomass utilization, to investigate the structural changes possibly related to the lignin involved. NMR characterization of the products isolated from the treated GG indicated that a phenyl dihydrobenzofuran, having typical C-H correlations at δC/δH 50.74/4.50 and 93.49/4.60 ppm in its HSQC spectrum, was produced from GG. In the pretreatment, the released formaldehyde from GG reacted fast with GG to form a novel 1,3-dioxane intermediate whose characteristic HSQC signals were: δC/δH 94.15–94.48/4.81–5.18 ppm and 80.82–83.34/4.50–4.94 ppm. The β-5 model, dihydrodehydrodiconiferyl alcohol, was converted into phenylcoumarone and stilbene having benzaldehyde that resulted from the allyl alcohol side chain. The β-β model, syringaresinol, was isomerized to form a mixture of syringaresinol, epi-, and dia-syringaresinol although being degraded slightly.

scholarly journals Structure-Activity Relationships of Sandalwood Odorants: Synthesis of a New Campholene Derivative

2010 ◽  
Vol 5 (9) ◽  
pp. 1934578X1000500
Author(s):  
Iris Stappen ◽  
Joris Höfinghoff ◽  
Gerhard Buchbauer ◽  
Peter Wolschann
Keyword(s):  
Structural Changes ◽  
Great Influence ◽  
Complete Loss ◽  
Side Chain ◽  
Side Chains ◽  
Quaternary Carbon ◽  
Structural Modifications ◽  
Structure Activity ◽  
Highly Sensitive ◽  
Sandalwood Odorants

Structural modifications of natural (-)-( Z)-β-santalol have shown that the sandalwood odor impression is highly sensitive, even to small structural changes. Particularly, the substitution of the quaternary carbon is of great influence on the scent. Epi-compounds with side chains in the endo-position possess sandalwood odor in only a few derivatives, whereas modifications at this side chain, as well as modification at the bicyclic ring systems mostly lead to a complete loss of sandalwood fragrance.

scholarly journals Preliminary Physico-Chemical Profile of Yashtimadhu Ghrita

2021 ◽  
Vol 12 (3) ◽  
pp. 2184-2189
Author(s):  
Swathy Vijayakumar ◽  
Mahadevan Subramaniam ◽  
Vandana Rani Madhavan ◽  
Anusree Dileep ◽  
Ramesh Narve Venkatesha ◽  
...  
Keyword(s):  
Acid Value ◽  
Solvent System ◽  
Organoleptic Evaluation ◽  
Cross Sectional ◽  
System A ◽  
Saponification Value ◽  
Physico Chemical ◽  
Acute Wound ◽  
Test Result

Yashtimadhu ghrita is a single-herbal ghee formulation mentioned in the classical texts of Ayurveda and is indicated in sadya kshatavrana (an acute inflammatory condition or an acute wound associated with trauma). It also minimizes the pain related to the wound. The present study is intended to create a finger print profile of Yastimadhu ghrita through its pharmacognostical identification and the physico-chemical analysis.  The genuineness of the dry specimen of Yashtimadhu (Glycyrrhiza glabra Linn.) was confirmed through organoleptic evaluation and cross-sectional microscopy. Yashtimadhu ghrita was prepared  as per the Sneha paka (preparation of unctuous formulations using ghee, oil etc.) procedure mentioned in Sarngadhara Samhita Madhyama khanda and the standard operative procedures specified in Ayurvedic pharmacopoeia of India. The test result of the finished product shows Acid value 6.7, saponification value 213.4, and Refractive index value1.455 at room temperature, Iodine value 38.7, LOD 0.64. TLC and HPTLC were carried out for the characterization of the plant material in an appropriate solvent system. A total of nine spots were distinguished in 254 nm and five spots in 366 nm during the HPTLC scanning. The Rf value pertaining to the spots were identical in the methanolic extract which indicates the presence of definite constituents in Yashtimadhu ghrita.

NMR Characterization of Side Chain Flexibility and Backbone Structure in the Type I Antifreeze Protein at Near Freezing Temperatures†

Biochemistry ◽  
1996 ◽  
Vol 35 (51) ◽  
pp. 16698-16704 ◽  
Author(s):  
Wolfram Gronwald ◽  
Heman Chao ◽  
D. Venkat Reddy ◽  
Peter L. Davies ◽  
Brian D. Sykes ◽  
...  
Keyword(s):  
Antifreeze Protein ◽  
Side Chain ◽  
Type I ◽  
Chain Flexibility ◽  
Nmr Characterization ◽  
Backbone Structure ◽  
Freezing Temperatures

Synthesis and NMR characterization of a series of linear monodisperse poly(aryl ether ketone) and poly(aryl ether sulfone) oligomers

1994 ◽  
Vol 195 (8) ◽  
pp. 2779-2789 ◽  
Author(s):  
Paolo Finocchiaro ◽  
Giorgio Montaudo ◽  
Patrizia Mertoli ◽  
Filippo Samperi
Keyword(s):  
Aryl Ether ◽  
Nmr Characterization ◽  
Aryl Ether Ketone ◽  
Ether Ketone

An Increase in Side Chain Entropy Facilitates Effector Binding:  NMR Characterization of the Side Chain Methyl Group Dynamics in Cdc42Hs†

Biochemistry ◽  
2001 ◽  
Vol 40 (15) ◽  
pp. 4590-4600 ◽  
Author(s):  
Adrienne P. Loh ◽  
Norma Pawley ◽  
Linda K. Nicholson ◽  
Robert E. Oswald
Keyword(s):  
Group Dynamics ◽  
Side Chain ◽  
Methyl Group ◽  
Nmr Characterization ◽  
Methyl Group Dynamics ◽  
Effector Binding

Solid state NMR characterization of zeolite beta based drug formulations containing Ag and sulfadiazine

RSC Advances ◽  
2015 ◽  
Vol 5 (100) ◽  
pp. 81957-81964 ◽  
Author(s):  
Pavletta Shestakova ◽  
Charlotte Martineau ◽  
Vesselina Mavrodinova ◽  
Margarita Popova
Keyword(s):  
Solid State Nmr ◽  
Structural Changes ◽  
Antibacterial Properties ◽  
Drug Formulations ◽  
Zeolite Framework ◽  
Drug Molecules ◽  
Nmr Characterization ◽  
Matrix Interactions ◽  
Dual Drug

The paper presents an investigation of structural changes of zeolite carrier, drug–matrix interactions and localization of drug molecules within the zeolite framework in dual drug formulations with antibacterial properties.

scholarly journals Chemical Characterization of Kraft Lignin Prepared from Mixed Hardwoods

Molecules ◽  
2021 ◽  
Vol 26 (16) ◽  
pp. 4861
Author(s):  
Ji-Sun Mun ◽  
Justin-Alfred Pe Pe III ◽  
Sung-Phil Mun
Keyword(s):  
Carbon Content ◽  
Structural Changes ◽  
Chemical Characterization ◽  
Structural Features ◽  
Kraft Lignin ◽  
Kraft Pulping ◽  
Nucleophilic Attack ◽  
Low Oxygen ◽  
Structural Modifications

Chemical characterization of kraft lignin (KL) from mixed hardwoods (Acacia spp. from Vietnam and mixed hardwoods (mainly Quercus spp.) from Korea) was conducted for its future applications. To compare the structural changes that occurred in KL, two milled wood lignins (MWLs) were prepared from the same hardwood samples used in the production of KL. Elemental analysis showed that the MWL from acacia (MWL-aca) and mixed hardwood (MWL-mhw) had almost similar carbon content, methoxyl content, and C9 formula. KL had high carbon content but low oxygen and methoxyl contents compared to MWLs. The C9 formula of KL was determined to be C9H7.29O2.26N0.07S0.12(OCH3)1.24. The Mw of KL and MWLs was about 3000 Da and 12,000–13,000 Da, respectively. The structural features of KL and MWLs were investigated by Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance spectrometry (1H, 13C NMR). The analyses indicated that KL underwent severe structural modifications, such as γ-carbon cleavage, demethylation, and polycondensation reactions during kraft pulping, which resulted in increased aromatic content and decreased aliphatic content. The main linkages in lignin, β-O-4 moieties, were hardly detected in the analysis as these linkages were extensively cleaved by nucleophilic attack of SH- and OH- during pulping.

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