RAPID COMMUNICATIONS IN MASS SPECTROMETRY
·
2018
·Vol. 32
·期 17
·1521-1528
·
IF 1.97
Sheng-Kang Wang,Xian-Yong Wei,Sheng Li,Fang-Jing Liu,Yu-Gao Wang,Zhan-Ku Li,Chong Shi,Zheng Yang,Zhi-Min Zong
Rationale Coal oxidation produces carboxylic acids (CAs), including aliphatic acids, benzoic acids, and benzenepolycarboxylic acids, which are important fine chemicals which could be used to understand the structural features of coals. However, detecting CAs usually presents great challenges due to extremely troublesome pretreatments. Therefore, it is essential to develop an analytical method for the rapid detection of CAs from coal oxidation. Methods A series of model compounds (MCs) of oxidation products and two practical samples were investigated by direct analysis in real time time-of-flight mass spectrometry (DART-TOFMS) under three different analytical conditions (ionizing gas temperature, organic solvent, and MC concentration). Results Ionizing methyl benzoate, dimethyl phthalate, and dimethyl adipate produces typical ions of methyl esters, including [M − OCH 3 ] + , [M + H] + , and [M + NH 4 ] + . In contrast, the characteristic ions generated from CAs are polymer ions, such as [2 M + NH 4 ] + , [3 M + NH 4 ] + , [4 M + NH 4 ] + , and [5 M + NH 4 ] + , indicating the strong intermolecular hydrogen-bond interaction among CAs. Conclusions Results suggest that DART-TOFMS could rapidly analyze CAs or esters in coal oxidation products according to their typical ions to further gain deep insights into the coal structure.
研究领域:
分析化学
·
能源化学
✓ 已验证
DOI
PubMed
高影响因子
Foods
·
2024
·Vol. 13
·期 2
·261
·
IF 4.7
Shanshan Liu,Mingyue Shen,Jianhua Xie,Bohan Liu,Chang Li
2-Monochloropropane-1, 3-diol (2-MCPD) esters and 3-monochloropropane-1,2-diol (3-MCPD) esters, a class of substances potentially harmful to human health, are usually formed during the refining of vegetable oils under high temperature. The effects of endogenous antioxidants in vegetable oils on the formation of 2- and 3-MCPD esters is still unknown. In this study, the effects of endogenous antioxidants (α-tocopherol, stigmasterol and squalene) on the formation of 2- and 3-MCPD esters in model thermal processing of camellia oil were investigated. The possible formation mechanism of 2- and 3-MCPD esters was also studied through the monitoring of acyloxonium ions, the intermediate ions of 2- and 3-MCPD esters formation, and free radicals by employing infrared spectra and electron paramagnetic resonance (EPR), respectively. The results indicated that the addition of α-tocopherol had either promoting or inhibiting effects on the formation of 2- and 3-MCPD esters, depending on the amount added. Stigmasterol inhibited the formation of 3-MCPD ester and 2-MCPD ester at low concentrations, while promoting their formation at high concentrations. Squalene exhibited a promotional effect on the formation of 3-MCPD ester and 2-MCPD ester, with an increased promotion effect as the amount of squalene added increased. The EPR results suggested that CCl3•, Lipid alkoxyl, N3• and SO3• formed during the processing of camellia oil, which may further mediate the formation of chlorpropanol esters. This study also inferred that squalene promotes the participation of the free radical in chlorpropanol ester formation.Keywords:MCPD esters;endogenous antioxidants;camellia oil;mechanism
研究领域:
食品科学
·
生物化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ENERGY & FUELS
·
2020
·
IF 3.421
Yangyang Xin,Yufeng Hu,Mengchen Li,Kebin Chi,Shang Zhang,Fei Gao,Siqi Jiang,Yichuan Wang,Chunxiao Ren,Guohua Li
Alkylation catalyzed by concentrated sulfuric acid (H2SO4) is an important process for industrial production of excellent high octane gasoline blending components. This process has some vital drawbacks such as extensive side reactions and high consumption of H2SO4 due to the presence of the most notorious impurities including H2O, acid soluble oil (ASO), and esters. In this study, isobutane alkylation was studied with H2SO4 (275 mL) in a batch reactor at −10 to 0 °C and 0.45 MPa, with the corresponding stirrer speed, feed rate, acid/hydrocarbon volume ratio, and isobutane/isobutylene volume ratio being 3000 rpm, 5.0 mL/min, 1.2, and 14.3, respectively. The effects of the acid strength and composition of acid on the alkylate quality were investigated. The composition of used acid was analyzed. The results show that used acid is mainly composed of roughly 89% free H2SO4, 6% H2O, 2% esters, and 3% ASO. The compounds existing in the ASO extracted from used acid were identified, and their concentrations were quantitatively determined. The results show that the most abundant ASO molecules are five-membered or six-membered cyclic homoannular conjugated olefins such as cyclopentadiene (15.67%) and cyclohexadiene (14.12%). The effects of acid strength, H2O, ASO, and esters on alkylation depend strongly on the concentrations of H2SO4 and these impurities. Therefore, their optimal concentrations were determined to achieve advantageous effects on the alkylation. The results are about 93–95% for H2SO4, 2–4% for H2O, 1.5–2.5% for ASO, and 0.4–1% for esters, beyond which an adverse effect will appear. Under the optimal concentrations, the value of the research octane number, the trimethylpentane (TMP)/dimethylhexane ratio, and the contents of C8 and TMP remained steady at high levels of about 92–93, 5.8–6.3, 68–70, and 58–60%, respectively.
研究领域:
化学工程
·
能源科学
✓ 已验证
DOI
高影响因子
CATALYSIS COMMUNICATIONS
·
2014
·
IF 3.32
Qian Han,Xingquan Xiong,Sizhong Li
An efficient, green and scale-up synthesis of amides from esters and amines has been developed using Ru-MACHO as a readily available catalyst. A diverse range of amides were obtained in moderate to excellent yields (55–98%). Furthermore, when the scale of the amidation reaction was increased to 240.0 mmol, the desired amide still could be obtained in high yield (48.2 g of N -benzylbenzamide, 95%).
研究领域:
有机化学
·
催化化学
✓ 已验证
DOI
高影响因子
RSC Advances
·
2020
·Vol. 10
·期 31
·18192-18199
·
IF 3.119
Zihao Yang,Taiheng Yin,Fengfan Zhang,Wei Wu,Meiqin Lin,Zhaoxia Dong,Juan Zhang
To study the microscopic dispersion state of CO2 in different ester solvents, the solubility, volume expansion coefficients and in situ Fourier transform infrared (FTIR) spectra of the CO2–ester system were measured. The results show that the solubility and expansion coefficient of CO2 in ester solvents decreases as the hydrocarbon chain increases. As the pressure increases, the infrared absorption peaks of CO2 and the functional groups characteristic of ester molecules shift, indicating that CO2 molecules interact with ester molecules and that CO2 would destroy the interactions between the ester molecules. The hydrocarbon chain length of the ester molecules has a significant effect on the infrared absorption peak of the CO2–ester system. As the hydrocarbon chain length increases, the CO2 absorption peak shift and peak shift of the carbonyl groups in the ester gradually decrease.
研究领域:
化学工程
·
物理化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Catalysts
·
2016
·Vol. 6
·期 9
·143
·
IF 2.964
Lincai Peng,Ruili Tao,Yu Wu
Levulinate ester has been identified as a promising renewable fuel additive and platform chemical. Here, the use of a wide range of common metal salts as acid catalysts for catalytic upgrading of biomass-derived furfuryl alcohol to butyl levulinate was explored by conventional heating. Both alkali and alkaline earth metal chlorides did not lead effectively to the conversion of furfuryl alcohol, while several transition metal chlorides (CrCl3, FeCl3, and CuCl2) and AlCl3exhibited catalytic activity for the synthesis of butyl levulinate. For their sulfates (Cr(III), Fe(III), Cu(II), and Al(III)), the catalytic activity was low. The reaction performance was correlated with the Brønsted acidity of the reaction system derived from the hydrolysis/alcoholysis of cations, but was more dependent on the Lewis acidity from the metal salts. Among these investigated metal salts, CuCl2was found to be uniquely effective, leading to the conversion of furfuryl alcohol to butyl levulinate with an optimized yield of 95%. Moreover, CuCl2could be recovered efficiently from the resulting reaction mixture and remained with almost unchanged catalytic activity in multiple recycling runs.Keywords:biofuel;furfuryl alcohol;catalytic upgrading;metal salt;levulinate ester
研究领域:
化学工程
·
可再生能源
✓ 已验证
产品关联
DOI
高影响因子
PROCEEDINGS OF THE COMBUSTION INSTITUTE
·
2018
·
IF 5.336
Linlin Yi,Huan Liu,Kangxin Xiao,Geyi Wang,Qiang Zhang,Hongyun Hu,Hong Yao
The fast pyrolysis of biomass with catalysts is a promising route for producing upgraded bio-oil as an alternative energy source . A CaO catalyst prepared from organic calcium compounds (Org-CaO) was first used to upgrade the pyrolysis oil of Jatropha curcas seeds in situ. Calcium d -gluconate monohydrate, calcium citrate tetrahydrate, and calcium acetate hydrate were employed as the organic precursors in this work. The results showed that Org-CaO exhibited better deoxygenation ability to produce more hydrocarbons than conventional CaO derived from Ca(OH) 2 (CH CaO). Acids accounted for 83% of the oxygenated compounds in the raw bio-oil and were almost completely removed via CaO. For bio-oil catalyzed by Org-CaO, the fraction of esters in the oxygenated compounds was only ∼9%, which was 20% less than that in CH CaO bio-oil. The relative content of ketones and alcohols in Org-CaO bio-oil increased by 16% versus that in CH CaO bio-oil. Org-CaO exhibited a remarkably larger pore size and much smaller particle sizes. Thus, Org-CaO entered into the fuel through the pore channels, and this promoted the formation of chemical crosslinking points between CaO and oxygenated groups. In addition, the basicity and the amount of basic sites for Org-CaO increased versus CH CaO. Thus, the adsorption forms of oxygen-containing groups in the bio-oil on the basic sites of CaO changed: the carboxyl groups were removed from the acids and were absorbed in a stable form of unidentate carbonate on oxygen vacancies (O 2− ). The stable form was bidentate carbonate on Ca 2+ –O 2− . In addition, oxygen vacancies on Org-CaO extracted more hydroxyl groups from the acids, resulting in dehydroxylation of acids to form ketones and alcohols.
研究领域:
能源植物学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING COMMUNICATIONS
·
2023
·
IF 2.5
Yanxiao Chen,Huifen Zhang,Xian Luo,Shiyun Jiao,Baocai Li,Mi Zhang
Crude montan wax (CMW) is a natural wax extracted directly from lignite by organic solvents that can be prepared into deresined montan wax (DMW) by the deresination process and then bleached into refined montan wax (RMW) by an oxidation process. Based on the different requirements for the DMW properties in different applications, a study on effects of the different factors on the deresination rate in CMW and the residual montan resin (MR) content on basic properties of DMW was carried out in this work. It was found that ethyl acetate displays an improved deresination effect, and that time and temperature are the two key factors that affect the CMW deresination rate (ǀ r ǀ > 0.9). With the increase in the residual MR contents in DMWs, the melting point of DMW decreased while its melting range widened, and its friability, acidity and saponification values increased. Gas chromatography-mass spectrometry analysis revealed that DMWs are rich in fatty esters and acids. It is concluded that the differences in their properties are related to the changes in the amount and content of the acids and esters.
研究领域:
化学工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MOLECULAR LIQUIDS
·
2024
·
IF 5.3
Xiaogang Shang,Songwei Zhang,Huimin Yang,Songbo Li,Litian Hu
In this study, four types of ionic liquids (ILs) were synthesized and their high-temperature tribological and extreme pressure properties in pentaerythritol ester (PE) oil were systematically evaluated. Compared with commercial additive zinc dialkyl dithiophosphates (ZDDP), ILs markedly improve the load-bearing capacity and high-temperature lubrication performance of PE oil. In particular, 2-n-undecylimidazolium O,O-dioctyl dithiophosphate ([C 11 -IM][C 8 -DDP]) showed the best lubricating effect at high temperature. The tribo-film of worn surface was analyzed by SEM, EDS, XPS and FIB-TEM, and the lubrication mechanism of ILs was systematically studied. Results proved that the tribochemical reactions occurred between ILs and the worn surface, resulting in the formation of a tribo-film consisting of Fe 2 O 3 , FePO 4 , FeS, Fe x (SO 4 ) y and nitrogenous organic compounds.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF CHROMATOGRAPHY A
·
2025
·
IF 4
Yuxin Liu,Chenjie Ma,Mantang Chen,Jufang Hao,Wei Liu,Jingjing Yu
Pyrethroid insecticides (PYs) overuse poses ecological and health risks, leading to tightened restrictions on maximum residue limits (MRLs) by regulatory bodies like the European Union and China's National Food Safety Standards. It is important to develop multi-residue analytical methods for PYs residues. In present work, oleic acid-coated Fe 3 O 4 nanoparticles (Fe 3 O 4 -OA) were dispersed in hydrophobic deep eutectic solvents (HDES) to prepare ferrofluids (FFs), with the HDES synthesized from coumarin and thymol at a 1:2 molar ratio. And the HDES-FF was subsequently utilized as a vortex-assisted liquid-phase microextraction sorbent for the enrichment of 16 PYs, combined with GC–MS/MS analysis. HDES-FF could effectively enrich PYs within merely 3.5 min according to π-π stacking interactions and hydrophobic effects, while Fe 3 O 4 -OA nanoparticles were responsible for magnetic separation. It could successfully solve the problem of separation difficulty after liquid-liquid microextraction based on DES. Simultaneously, thermogravimetric analysis confirmed that the HDES could decompose at injection port of GC–MS/MS instrument, and mass spectrometry signals of the decomposed HDES could not be collected by adjusting the solvent delay time. Thus, it could effectively protect the ion source from contamination, making DES compatible with GC–MS methods. The detection limit (LOD) of the proposed method is 0.41–7.91 ng/mL, with the recoveries of 83.33–106.02 %. The intra-day and inter-day relative standard deviations (RSDs) are less than 4.20 % and 6.94 %, respectively. The method successfully detected 16 PYs in various real fruit and vegetable samples.
研究领域:
食品安全检测
·
农药残留分析
·
食品化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF FOOD SCIENCE
·
2024
·Vol. 89
·期 3
·1485-1497
·
IF 3.2
Xiaoying Li,Chunsheng Liu,Junkai Wu,Xiao Xiao,Libin Zhang,Caixia Chen,Annette S. Wilson,Fuhang Song
To recognize the key ester-related volatile compounds, 5 types of peaches including 54 late-ripening peach materials were examined by headspace solid-phase microextraction coupled with gas chromatography–mass spectrometry and E-nose. Here, a large number of esters were identified to be released by ripe peach fruits and were mainly characterized by fruity, green, and fatty notes. The variety and content of esters had greatly changed within or between cultivars, indicating that the fruit volatiles were highly differentiated depending on the specific genotypes and cultivation conditions. The ester types showed that fatty acid-derived C6 alcohols and methyl-/ethyl- short-chain alcohol were the main ester precursors, which were more likely to be utilized and well selected by alcohol acyltransferases, whereas the preference of acyl donors was not observed. The common peach type, which exhibited a unique volatile profile, displayed broader diversity and more abundant characteristics in ester-related volatiles than the other four types. A total of 19 key esters were identified as the main components and the content of most esters showed no significant difference among different peach types. Some key esters had even been enriched in nectarines. Moreover, the multiple discriminant analysis revealed a possible relationship between peach types and the domestication of the peach evolution. This study investigated ester-related volatiles released by different types of peach fruits and can be further used to evaluate the peach qualities, providing an important reference for peach breeding and processing.
研究领域:
植物学
·
食品科学
·
园艺学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF FOOD SCIENCE
·
2024
·
IF 3.2
Yueqi An,Wenrong Li,Shuo Shen,Ku Li,Jiangyong Guo,Shanbai Xiong
Warmed-over flavor (WOF) is an off-flavor in surimi gels. Yeast extract (YE) could improve the aroma properties of food. However, the effect of YE on the WOF in surimi gels and its mechanism was still unclear. In this study, aroma profiles, the composition of aroma compounds and aroma precursors, concentrations of WOF compounds, and thiobarbituric acid reactive substances (TBARS) of surimi gels with different amounts of YE were investigated by molecular sensory science and chromatographic techniques. Moreover, the effect of pyrazines and esters introduced by YE on WOF was also tested by sensory analysis. The addition of no less than 1% YE to surimi gels significantly weakened WOF. However, YE did not decrease the concentrations of WOF compounds and did not change the fatty acid composition and TBARS in surimi gels. Conversely, the addition of YE significantly increased the contents of free amino acids, N-containing compounds, and esters in surimi gels. The contents of total free amino acids, 2,6-dimethylpyrazine, and ethyl acetate in surimi gels with 2.5% YE were 1.5, 21, and 2.1 times higher than those in the control, respectively. Additionally, the sensory results of the spiked aroma models containing WOF compounds, 2,6-dimethylpyrazine, and esters showed that more than 9.4 µg/kg of 2,6-dimethylpyrazine with a baked-potato note and more than 6.1 µg/kg of ethyl acetate and 11.2 µg/kg of butyl acetate with a fruity note could significantly mask WOF. In conclusion, WOF in surimi gels could be masked by YE due to the high concentrations of pyrazines and esters. Practical Application : Yeast extracts could decrease the warmed-over flavor (WOF) due to the high concentrations of pyrazines (baked-potato note) and esters (fruity note). This finding extends the application of yeast extracts in the food industry. On the other hand, this study presents a reasonable solution for the reduction of WOF in surimi products.
研究领域:
食品科学
·
分子感官科学
·
风味化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）