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Biocatalyzed Synthesis of Antidiabetic Drugs
Published in Peter Grunwald, Pharmaceutical Biocatalysis, 2019
The thioester rac-4 was resolved with Pseudomonas cepacia lipase in the presence of a tert-amine base, trioctylamine. The desired acid (S)-5 is stable, and residual (R)-thioester was racemized by deprotonation and reprotonation catalyzed by the organic base, which cannot make a similar undesired racemization step of (S)-5, because the α protons of the carboxylate product are not acidic enough to be deprotonated by tert-amine bases. Although this process was scaled to grams, AZD 4619 was discontinued because of hepatotoxicity problems detected in Phase I (Thulin et al., 2008). Similarly, the resolution of the racemic α-chloro thioester intermediate 6 has been described using the same strategy, shown in Fig. 11.10 (Dow et al., 2012) to furnish acid (S)-7. Remarkably, the use of a protease instead of a lipase allowed the synthesis of the antipode (R)-7, although with a lower ee (90% with Savinase vs. 98% with lipase). DKR process to synthesize a precursor of AZD 46919.
Solution-Grown n-Type ZnO Nanostructures Synthesis, Microstructure, and Doping
Published in Zhe Chuan Feng, Handbook of Zinc Oxide and Related Materials, 2012
Rodrigo Noriega, Saahil Mehra, Alberto Salleo
Trioctylamine, a tertiary amine with three branched alkyl chains, exhibits a strong coordinating power and enables growth of high aspect ratio structures. This effect is analogous to that observed when the high aspect ratio nanowires are grown in aqueous environments under the presence of methenamine. It has been argued that trioctylamine could act as a ligand during the synthesis as well, strongly coordinating to (11–20) planes and inhibiting radial growth [21]. To further explore the effects of the solvent alkyl chain length on the aspect ratio of the ZnO nanostructures obtained, O’Brien and coworkers synthesized ZnO nanostructures using tertiary amine solvents with three different alkyl chain lengths. They observed the highest aspect ratio structures (aspect ratio: 20–38) with the shortest alkyl chain length solvent, trihexylamine, and lowest aspect ratio structures with tridodecylamine. The tertiary amine is proposed to stabilize the polar surfaces and quench radial growth, and the lower aspect ratios observed with tridodecylamine was attributed to steric hindrance from the longer alkyl chains attached to the amine [22].
A Comparison Between Trioctylamine (TOA) and Tris(2-Ethylhexyl) Amine (TEHA) in Solvent Extraction of Sulfuric Acid*
Published in Solvent Extraction and Ion Exchange, 2023
Aidin Heidari, Shahryar Shahini, Davoud Haghshenas Fatmehsari, Eskandar Keshavarz Alamdari
This study investigates the extraction of sulfuric acid using two organic amine extractants, namely trioctylamine (TOA)[62] and tris(2-Ethylhexyl)amine (TEHA). The results show that sulfuric acid extraction behavior by the two amine extractants is different. Specifically, when using TOA as the extractant, the percentage of sulfuric acid extraction decreases as the initial sulfuric acid concentration increases. Conversely, when TEHA is used, a higher percentage of acid extraction is obtained with an increase in the initial concentration of the acid. This suggests that TOA has a higher affinity for sulfuric acid absorption compared to TEHA, especially at lower acid concentrations. Therefore, TOA may be more favorable when increasing the pH in an acidic aqueous solution for precipitation or extraction of other metals is the goal. On the other hand, TEHA has a higher capacity for sulfuric acid extraction, making it more suitable for extracting sulfuric acid at higher concentrations (more than 150 g/L) as it will decrease the number of mixer settlers at the extraction stage. In conclusion, the study suggests that the choice of extractant should be based on the specific requirements of the extraction process and economic issues. (In terms of pricing, TOA and TEHA are in similar price ranges, with TEHA being priced at about 1.14 times that of TOA.) Additional conclusions are as follows:
Insights into the microbiomes for medium-chain carboxylic acids production from biowastes through chain elongation
Published in Critical Reviews in Environmental Science and Technology, 2022
Xingdong Shi, Lan Wu, Wei Wei, Bing-Jie Ni
The material of the membrane is a crucial factor governing the extraction efficiency of target products. Polytetrafluoroethylene (Qin & Sheth, 2003), polyvinyl alcohol (Kusumocahyo et al., 2000), and poly (dimethyl siloxane) (Li et al., 2004) have been utilized for separating the carboxylic acids from water. However, some membranes may also allow the diffusion of water vapor and ammonia, thereby, decreasing the selectivity of the target molecules (Qin & Sheth, 2003; Thongsukmak & Sirkar, 2007). The long-chain aliphatic amine extractants or organophosphorus extractants (e.g. trioctylphosphine oxide, tributylphosphate, tridodecylamine, and trioctylamine) can form strong acid–amine interaction with carboxylic acids (Kertes & King, 1986; Thongsukmak & Sirkar, 2007). This interaction would then improve the combination between extractant and MCCAs, thereby decreasing the diffusion of water vapor and ammonia. Hence, these molecules with high selectivity to carboxylic acids might be the potential extracts in perstraction system. According to recent research, Aliquat 336 and TOPO have the best performance on recovering C2-C6 carboxylates from synthetic solutions compared with other extractants (Kaur et al., 2020). However, current studies only applied TOPO as the extraction agent for the recovery of MCCAs (Table S6). Further studies on various extraction agents are therefore suggested in order to establish more cost-effective extraction method to separate MCCAs.
Parametric optimization of green synergistic reactive extraction of lactic acid using trioctylamine, Aliquat336, and butan-2-ol in sunflower oil by response surface methodology
Published in Chemical Engineering Communications, 2019
In conventional LA solvent extraction, number of extractants and solvents such as butanol, ethyl acetate, decanol, octanol, chloroform, hexane, and tertiary amines were explored (Kyuchoukov et al., 2001). The most commonly used extractants in solvent extraction of carboxylic acids are phosphorous bonded oxygen-bearing, oxygen-bearing and hydrocarbon, and high molecular weight aliphatic amines (Gorden et al., 2015). But the amine-based complex solvent system, especially tertiary (trioctylamine [TOA] and Alamine336) and quaternary amines (Aliquat336) has been considered as the most efficient and effective extractant system. The amine-based extractants provide high extraction yield (>90%) and are less costly w.r.t. phosphorus-based extractants (such as tri-n-octylphosphine oxide (TOPO) and tributyl phosphate (TBP)) (Wasewar, 2005). Generally, these extractants are solid (e.g. TOPO) and viscous (e.g. Aliquat336) in nature. Therefore, these should be used along with the organic solvents (such as 1-decanol, n-heptane, and oleyl alcohol) which will further help in controlling density, interfacial tension, and viscosity of the extractants (Keshav and Wasewar, 2009). The most commonly used organic solvents are organic polar protic solvent (butanol, octanol, decanol, and oleyl alcohol) as these provide good solvation power for the acid-extractant complex, high distribution coefficient, and also help in preventing the formation of the third phase which is responsible for affecting the extraction power of these extractants (Wasewar, 2005).