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Tannins as Precursors of Supercapacitor Electrodes
Published in Eduardo Rincón-Mejía, Alejandro de las Heras, Sustainable Energy Technologies, 2017
Vanessa Fierro, Angela Sánchez-Sánchez, Alain Celzard
The terms “hydrolysable” and “condensed” tannins are used to distinguish between the two important classes of vegetable tannins, namely, gallic acid-derived and flavan-3, 4-diol-derived tannins, respectively. This chapter will deal only with condensed tannins, which are characterized by aromatic rings bearing hydroxyl groups. Due to such polyphenolic structure, tannins are able to undergo the same kinds of chemical reactions as those known for resorcinol or phenol, two synthetic molecules of petrochemical origin used to prepare commercial resins. There are four types of poly-flavonoids composing condensed tannins: (1) prorobinetinidin, (2) prodelphinidin, (3) profisetinidin, and (4) procyanidin as shown in Figure 13.1. The concentration of these polyflavonoids in tannin depends on the plant species, and the number and the position of –OH functionalities change their reactivity. Thus, for mimosa tannin, resorcinol A-ring and pyrogallol B-ring (constituting a robinetinidin flavonoid unit) are the main patterns at about 90% of the phenolic content of the tannin itself (Pizzi and Mittal, 2003). For quebracho tannin, resorcinol A-ring and catechol B-ring (constituting a profisetinidin flavonoid unit) are the main patterns constituting more than 80% of the phenolic content of the tannin itself (Pizzi and Mittal, 2003). Pine tannins are based on a phloroglucinol A-ring and a catechol B-ring (giving a procyanidin-type tannin) or on a phloroglucinol A-ring and a pyrogallol B-ring (leading to a prodelphinidin-type tannin), see again Figure 13.1. Consequently, the A-rings of these condensed tannins are about 6–7 times more reactive than the A-rings of mimosa and quebracho-type tannins (Pizzi and Mittal, 2003).
Anaerobic Metabolism of Aromatic Compounds
Published in Donald L. Wise, Bioprocessing and Biotreatment of Coal, 2017
John D. Haddock, James G. Ferry
Field and Lettinga [117] investigated the toxicity of gallotannic acid to methanogenesis during the anaerobic digestion of volatile fatty acids by granulated sludge. Gallotannic acid, a polyester of gallic acid, severely decreased rates of methane production relative to unamended controls and those with additions of gallic acid and pyrogallol. However, gallotannic acid as well as gallic acid and pyrogallol were rapidly degraded by the sludge.
Oragnic Chemicals in the Environment
Published in Richard A. Larson, Eric J. Weber, Reaction Mechanisms in Environmental Organic Chemistry, 2018
Richard A. Larson, Eric J. Weber
Another type of uniformist model is that of Flaig (1950, Figure 1.23) which considered humic materials to be polyphenol ethers. This sort of structure appears to be inspired by the indisputable fact that solutions of polyphenols such as pyrogallol and hydroquinone turn brown on standing, especially in the presence of alkali.
Insights on sustainable fuels: a new benzimidazole derivative with potential as a diesel-biodiesel blend additive
Published in Biofuels, 2023
Vitor S. Duarte, Raquel F. Naves, Adailton J. Bortoluzzi, Eduardo C. M. Faria, Aline M. da Silva, Vânia Mori, Christian G. Alonso, Guilherme R. Oliveira, Hamilton B. Napolitano
The Rancimat tests were performed in triplicate, and the average of the results showed that after 140 days the fuel had oxidative stability of 26.3 h (Table 4). In Brazil there is still no legislation in force that establishes the minimum oxidation stability limit at 110 °C for diesel-biodiesel blend; however, according to Brazilian Resolution ANP 798/2019 [174], the minimum oxidation stability limit for biodiesel to be sold is 12 h for 60 days. According to the European Committee of Standardization, the minimum biodiesel oxidation stability required is 6 h at 110 °C (EN 14214) [175], but, since 2018, there has been a movement by groups of vehicle manufacturers, additive manufacturers, distributors, and vehicle components industries aiming to establish a minimum limit of 20 h in the Rancimat test. This means that fuel must meet this requirement when it is delivered to the final consumer. However, there is still no official regulation defining a limit for this property. Currently, the additives most used for fuels and biofuels are Butylated Hydroxytoluene (BHT), Butylated Hydroxyanisole (BHA), Tertiary Butyl Hydroquinone (TBHQ), Ditert-butylhydroquinone (DTBHQ), Propyl Gallate (PG), Pyrogallol (PY), α-Tocopherol (α-T), 2-Ethylhexyl Nitrate (EHN) and Gallic Acid (GA). Due to the great variety of diesel-biodiesel mixtures (additives and concentrations used), the values of oxidative stability can be diverse – however, results above 20 or near 30 h are acceptable. Table 4 shows values of the effects of antioxidants on biofuels and the effect of the BZD molecule on a B20.
Proton affinity and gas-phase basicity of pyrogallol and phloroglucinol: a computational study
Published in Journal of Coordination Chemistry, 2021
Collin M. Mayhan, Harshita Kumari, Julia M. Maddalena, Gabriel N. Borgmeyer, Carol A. Deakyne
Comparing the three neutral trihydroxybenzenes, from most favorable to least favorable, the stability order is (in kJ mol−1): pyrogallol (0.0) > hydroxyquinone (7.7) ≥ phloroglucinol (9.2 [36]). The trend changes to pyrogallol (0.0) > phloroglucinol (6.3) ≥ hydroxyquinone (8.8 [36]) for ΔE [42] and ΔH. The ΔH values are given in parentheses; the ΔE values agree within ±2 kJ mol−1. That pyrogallol is the most favorable base can be attributed to the cooperative H-bonding exhibited by that base. However, the relative stability of the remaining two bases is determined by entropic effects and not by the presence of intramolecular H-bonds. Mammino and Kabanda [42] have attributed the trends in energy among the polyphenols to an interplay of three factors: intramolecular H-bonding, symmetry, and directional uniformity of the hydroxyl hydrogen atoms. For the benzene triols, they have suggested that the latter two factors outweigh the former. Overall, however, although the same thermochemical trends have been observed at a variety of calculational levels, phloroglucinol and hydroxyquinol are so nearly equal in stability that small changes among the contributing factors can alter the trends between them.
Layered Double Hydroxide for Carbon dioxide mitigation from Bitumen and formation of Carbonic acid: A Step toward Achieving Greener Pavements
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2021
Priyam Nath Bhowmik, Anmol Singh, Pranjit Barman, Mokaddes Ali Ahmed
Viscosity grade 20 bitumen (Numaligarh Refinery Limited, Assam) was utilized for the research purpose. Ammonium hydroxide (Sigma Aldrich), Cuprous chloride (Sigma Aldrich), alkaline pyrogallol solution (Sigma Aldrich), and Potassium hydroxide (Fisher Scientific) were used for the evaluation of the GHGs. Aluminum nitrate nonahydrate [Al(NO3)3.9H2O] (Sigma Aldrich), Calcium nitrate tetrahydrate [Ca(NO3)2.4H2O] (Sigma Aldrich), and Sodium hydroxide (NaOH) (Sigma Aldrich) were used for the synthesis of LDH. All chemicals were diagnostic grade and utilized with no further cleansing. De-carbonated water was acquired through boiling deionized water and utilized throughout all procedures.