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Microbial Bioconversion of Agro-Waste Biomass into Useful Phenolic Compounds
Published in Prakash K. Sarangi, Latika Bhatia, Biotechnology for Waste Biomass Utilization, 2023
Bhabjit Pattnaik, Prakash Kumar Sarangi, Padan Kumar Jena, Hara Prasad Sahoo
The vanilla extract comprises more than 200 components in its flavor profile. Out of these, the characteristic vanilla fragrance is primarily due to vanillin which occurs as the peak abundant organic compound. The concentration of vanillin ranges from 1.0–2.0% w/w of dry weight in treated Vanilla pods where it is gathered mainly in coupled form, predominantly as the β-D-glucoside. The vanilla beans do not display any trace of vanilla flavor at six to eight months following pollination when the green beans are yielded (Walton et al., 2003). Fermentation of vanilla pods is popularly called “curing.” It causes the hydrolysis of glucovanillin, glucoside of vanillin, as well as related β-D-glucosides by the action of the enzyme β-D-glucosidase. This results in the release of free vanillin and associated substances (particularly 4-hydroxybenzaldehyde) thus producing a pleasant aroma (Odoux et al., 2003).
Genetic Regulation of Principal Microorganisms (Yeast, Zymomonas mobilis, and Clostridium thermocellum) Producing Bioethanol/Biofuel
Published in Ayerim Y. Hernández Almanza, Nagamani Balagurusamy, Héctor Ruiz Leza, Cristóbal N. Aguilar, Bioethanol, 2023
Dania Sandoval-Nuñez, Teresa Romero-Gutiérrez, Melchor Arellano-Plaza, Anne Gschaedler, Lorena Amaya-Delgado
Chemical inhibitors are commonly present during Z. mobilis fermentation because these products may be present in LCB residues or may be derived from the fermentation itself [80]. The study of the expression profile of Z. mobilis with diverse inhibitors helps to characterize the metabolic pathways involved in cell detoxification processes. Changes in the cell growth and ethanol yield of Z. mobilis ZM4 in the presence of inhibitors such as phenolic aldehydes, furfural, and ethanol have been evaluated. Phenolic aldehydes are formed in the pretreatment of LCB used as raw material for the production of biofuels and have been reported as toxic agents that can affect cell growth and fermentation [81]. Yi et al. evaluated the genomic response of Z. mobilis ZM4 in the presence of the inhibitors 4-hydroxybenzaldehyde, syringaldehyde, and vanillin, identifying overexpressed genes from the respiratory chain and transporter genes (Table 4.3) that help reduce inhibitors to their corresponding phenolic alcohols and maintain ethanol production [82].
Phenolic Resin Adhesives
Published in A. Pizzi, K. L. Mittal, Handbook of Adhesive Technology, 2017
Phenolic resins based on the reaction of phenol with aldehydes to obtain phenolic resins not dependent on formaldehyde have also been developed, especially with biobased aldehydes. Recently, a method was developed to transform lignin-based aromatic aldehyde precursors, that is, 4-hydroxybenzaldehyde and vanillin, into reactive and difunctional biobased aromatic aldehydes. These were used to prepare formaldehyde-free partially biobased phenolic resins with thermal properties competitive with those of PF resins [59]. Other researchers have concentrated on using 5-hydroxymethylfurfural (HMF) produced in situ from glucose reacted with phenol to form resins to bind glass fiber composites. This resin is reported to be heat curable using cross-linking agents such as tetraethylammonium chloride [60,61].
Symmetrical and asymmetrical liquid crystal dimers: synthesis, characterisation and mesomorphic behaviour
Published in Liquid Crystals, 2019
Uhood Jabbar Al-Hamdani, Hanna S. Abbo, Ebtahal Hamid Shaheeb, Salam J. J. Titinchi
4-alkoxy benzaldehyde was synthesised according to the literature procedure [34] by adding a solution of 1mmol of 4-hydroxybenzaldehyde in ethanol to 1mmol potassium carbonate and 1mmol of the appropriate bromoalkane. The reaction mixture was refluxed with stirring for 24 hr. The reaction mixture was hot filtered the mother liquors were evaporated to dryness to afford a yellowish oily residue.
Thermal, spectroscopic and structural characterization of isostructural phase transition in 4-hydroxybenzaldehyde
Published in Phase Transitions, 2018
Packing (structural) polymorphism is very common in organic compounds arising due to more than one packing motif of the same compound. Thus in packing polymorphism, the same solid shows different crystal packing. An example of an organic polymorph is glycine, which is able to form monoclinic and hexagonal crystals. Studying polymorphs in organic solids is of importance as polymorphs may differ significantly in many important thermodynamic properties such as solubility and melting point, and kinetic properties such as dissolution rate and stability, as well as mechanical properties crucial in pharmaceutical industry [1,2]. 4-hydroxybenzaldehyde(4-HOBAL) an aromatic aldehyde is used in synthesis of various compounds like aldehyde methacrylates, benzopyrans, liquid crystalline compounds, etc. Aldehyde methacrylate has application in manufacturing dental materials as it can form strong and durable bonds with dentin [3]. Benzopyrans have wide applications in the perfume, cosmetic and pharmaceutical industry [4,5]. Two crystal structures of 4-HOBAL, recrystallized from ethylacetate (CCDC no. 676 161) and water (CCDC no. 1232287), respectively have been reported [6,7]. The crystal structure of 4-HOBAL crystallized from ethylacetate is monoclinic, P21/c, a = 6.6992 (8) Ȧ, b = 13.5550 (12) Ȧ, c = 7.1441 (11) Ȧ β = 112.871 (16)o. V = 597.74 (15) Ȧ3, Z = 4 [6]. While the crystal structure of 4-HOBAL crystallized from water is monoclinic, P21/c, a = 6.453 (5) Ȧ, b = 13.810 (8) Ȧ, c = 7.044 (6) Ȧ β = 107.94 (9)o. V = 597.2 Ȧ3, Z = 4 [7]. In both cases, the crystal structure is monoclinic, P21/c, and the crystal packing is stabilized by intermolecular hydrogen bonding (O-H···O) interactions between the hydroxyl and aldlehyde groups. However, noticeable differences are seen in their cell parameters. This communication reports temperature-induced polymorphism (polymorph I to polymorph II) seen in 4-HOBAL using differential scanning calorimeter (DSC). These polymorphs were further characterized using X-ray powder diffraction (XRPD) patterns and Raman spectra.