Saturated Carboxylate Research Articles

Prolonged corrosion protection via application of 4-ferrocenylbutyl saturated carboxylate ester derivatives with superior inhibition performance for mild steel

A series of 4-ferrcenylbutyl carboxylate esters with different alkyl chain length (C2-C4) of carboxylic acids were synthesized using Fe3O4@SiO2@(CH2)3-Im-bisEthylFc[I] nanoparticles as catalyst and have been characterized with FT-IR, 1H NMR, and 13C NMR. Ferrocenyl-based esters were used as corrosion inhibitors of mild steel in the 1M HCl solution as corrosive media. The corrosion inhibition efficiency of the synthesized ferrocenyl-based esters has been assessed by electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), atomic force microscopy (AFM), and scanning electron microscopy (SEM). The 4-ferrocenylbutyl propionate showed a more effective corrosion inhibition behavior among the studied esters with 96% efficiency after immersion in the corrosive media for 2 weeks. The corrosion inhibition mechanism is dominated by formation of passive layer of inhibitor on the surface of the mild steel by adsorption. Moreover, the adsorption characteristics of 4-butylferrcenyl carboxylate esters on mild steel were thoroughly explored using density functional theory calculations. It was found that the Fe atoms located around the C impurity in the mild steel are the most efficient and active sites to adsorb 4-butylferrcenyl carboxylate esters.

Mechanisms for the structural dependent transformation of 6:2 and 8:2 polyfluoroalkyl phosphate diesters in wheat (Triticum aestivum L.)

Polyfluoroalkyl phosphate esters (PAPs) are widely used and detected in various environmental media and organisms, but little is known about their behaviors in plants. In this study, the uptake, translocation and transformation of 6:2 and 8:2 diPAP in wheat using hydroponic experiments were investigated. 6:2 diPAP was more easily taken up by roots and translocated to shoots than 8:2 diPAP. Their phase I metabolites were fluorotelomer saturated carboxylates (FTCAs), fluorotelomer unsaturated carboxylates (FTUCAs) and perfluoroalkyl carboxylic acids (PFCAs). PFCAs with even-numbered chain length were the primary phase I terminal metabolites suggesting that they were mainly generated through β-oxidation. Cysteine and sulfate conjugates were the primary phase II transformation metabolites. The higher levels and ratios of phase II metabolites in the 6:2 diPAP exposure group indicated that the phase I metabolites of 6:2 diPAP were more susceptible to phase II transformation than that of 8:2 diPAP, which was confirmed by density functional theory calculation. Enzyme activity analyses and in vitro experiments demonstrated that cytochrome P450 and alcohol dehydrogenase actively participated in the phase Ⅰ transformation of diPAPs. Gene expression analyses showed that glutathione S-transferase (GST) was involved in the phase Ⅱ transformation, and the subfamily GSTU2 played a dominant role.

Iron-Mediated Coupling of Carbon Dioxide and Ethylene: Macrocyclic Metallalactones Enable Access to Various Carboxylates.

Treatment of (iPrPDI)Fe(N2)2 (iPrPDI, 2,6-(2,6-iPr2C6H3N═CMe)2C5H3N) with CO2 and ethylene resulted in the formation of a homologous series of saturated and unsaturated iron carboxylate products, (iPrPDI)Fe(O2CR), the distribution of which depends on the ratio of the reagents. The solid-state and electronic structures of a saturated product, (iPrPDI)Fe(O2CC2H5), were elucidated. Product distributions, deuterium labeling studies, and stoichiometric experiments support initial formation of a five-membered metallalactone intermediate, which undergoes subsequent ethylene insertions to generate macrocyclic metallalactones. Competitive β-hydride elimination, CO2 insertion, or reaction with H2 determines the fate of the metallalactone, the latter accounting for formation of iron complexes with saturated carboxylates. Similar reactivity was observed upon addition of propiolactone and ethylene to (iPrPDI)Fe(N2)2, supporting C-O oxidative addition and C-C bond formation through metallacycle intermediates.

A DFT Study of N-Heterocyclic Carbene Catalyzed [4+2] Annulation between Saturated Carboxylate withortho-Quinone Methide: Possible Mechanisms and Origin of Enantioselectivity

The possible mechanisms of N-heterocyclic carbene (NHC) catalyzed [4+2] annulation between saturated carboxylate and ortho-quinone methide have been investigated for the first time using density functional theory. The calculated results indicate that the entire catalytic cycle contains four reaction steps: (1) the nucleophilic attack on carbonyl carbon of saturated carboxylate by NHC, which is coupled with the dissociation of triazole-oxide anion, (2) the α-C(sp3)-H deprotonation by Bronsted base, (3) the [4+2] cycloaddition affording the SR/RS/SS/RR-configurational intermediates, and (4) the dissociation of NHC and products. The [4+2] cycloaddition step is stereoselectivity-determining, and the RS-configurational pathway is the most energy favorable path, which is consistent with the experimental observations. Frontier molecular orbital (FMO) analysis indicates that NHC can lower the energy barrier of [4+2] cycloaddition by reducing the energy gap of two reactant parters, which is further confirmed by the additional calculations of the uncatalyzed [4+2] cycloaddition pathway. In addition, non-covalent interaction and distortion energy analyses were performed for exploring the origin of the stereoselectivity. Moreover, the natural bond orbital (NBO) charge population and global reactivity index (GRI) analyses were also carried out to disclose the role of NHC.

Covalent attachment of alkene and alkyne groups on carbon surfaces by electrochemical oxidation of unsaturated aliphatic carboxylates

The covalent modification of glassy carbon electrodes by oxidation of unsaturated aliphatic carboxylates is reported in this work. It is shown that the presence of π-bonds on the hydrocarbon structure is essential to develop the grafting process, which does not occurs with totally saturated carboxylates. In this way, the glassy carbon surface modification with aliphatic chains containing alkene and alkyne groups was performed and the presence of such groups was demonstrated through a Heck and a Click reaction, allowing respectively a further functionalization with nitrobenzene and ferrocene groups.

Elucidating the Pathways of Poly- and Perfluorinated Acid Formation in Rainbow Trout

Several studies have shown that fluorotelomer-based compounds can be metabolized to poly- and perfluorinated carboxylates, such as perfluorooctanoate (PFOA). Research has predominately focused on the 8:2 fluorotelomer alcohol (8:2 FTOH), however, the biotransformation pathway is not well understood. Specifically, there is uncertainty regarding the biological fate of the 8:2 fluorotelomer unsaturated carboxylate (FTUCA) and 7:3 fluorotelomer saturated carboxylate (FTCA). The objective of this study was to further elucidate the pathway for 8:2 FTOH biotransformation through dosing rainbow trout with three 8:2 FTOH metabolism intermediates: the 7:3 FTCA (CF(3)(CF(2))(6)CH(2)CH(2)COO(-)), 8:2 FTCA (CF(3)(CF(2))(7)CH(2)COO(-)), and 8:2 FTUCA (CF(3)(CF(2))(6)CF horizontal lineCHCOO(-)). This study represents the first investigation of these three labile intermediate metabolites in an in vivo system. The parent compounds were dosed via the diet and the parent compounds and intermediates were monitored in the blood and liver during the 7-day uptake phase and 10-day elimination phase. Exposure to the 7:3 FTCA did not result in the formation and accumulation of PFOA, but resulted in low levels of the 7:3 FTUCA and perfluoroheptanoate, a novel finding. PFOA was formed in the 8:2 FTCA and 8:2 FTUCA dosing. In addition, the 7:3 FTCA was formed during exposure to both the 8:2 FTCA and 8:2 FTUCA. Elimination half-lives were 5.1 d (95% confidence interval: 3.1-14 d) for 7:3 FTCA, 1.2 d (1.1-1.3 d) for 8:2 FTCA, and 0.39 d (0.31-0.53 d) for 8:2 FTUCA. The observed differences in the elimination half-life may be the result of differences in either the depuration or metabolism rate. Based on the findings of this study, and reported analogous literature pathways, we proposed a "beta-like-oxidation" pathway for PFOA formation proceeding from the 8:2 FTUCA > 7:3 beta-keto acid > 7:2 ketone > PFOA. Alternatively PFOA could be formed directly through the beta-oxidation of the 7:3 beta-keto acid.

Determination of the Solubility Products in Water at 20 °C of 32 Metallic Carboxylates

The solubility products of 32 metallic carboxylates resulting from the precipitation of seven cations (Cd, Co, Cu, Mn, Ni, Pb, and Zn) with six linear saturated carboxylates (heptanoate, octanoate, nonanoate, decanoate, dodecanoate, and octadecanoate) are reported. Solubility measurements were performed using the analytical method with freshly precipitated metallic carboxylates. From the measured metal concentration and equilibrium pH value, solubility products, Ksp, were determined. The results indicate a linear relationship between the negative logarithm of the solubility product and the carbon number in the aliphatic chain that is valid from 7 to 12 carbons. The determination of the pKsp value of copper octadecanoate shows the limit of the linear model. Indeed, the experimental value obtained demonstrates that pKsp tends to a limiting value and becomes independent of the chain length.

Reductions of 2-enals, dehydrogenation of saturated aldehydes and their racemisation.

Enoate reductase or clostridia containing this enzyme (Clostridium tyrobutyricum or C. kluyveri) catalyse the reduction of alpha,beta-unsaturated aldehydes (enals). The enantiomeric purity of the saturated aldehydes obtained from alpha-substituted enals is usually rather low and depends heavily on the reaction conditions. The reduction of the corresponding allyl alcohols to the saturated alcohols leads to much higher enantiomeric purities, though the reduction of the enal corresponding to the allyl alcohol to the saturated aldehyde is an intermediary step in the reaction sequence allyl alcohol----saturated alcohol. The explanation seems to be the racemisation of saturated aldehydes caused by enoate reductase. This is illustrated by the reduction of (E)-2-methylcinnamyl aldehyde to (R)-2-methyl-3-phenylpropanal or (R)-2-methyl-3-phenylpropanol under different conditions and measuring the racemisation of the aldehyde as well as the hydrogen-deuterium exchange of 3-phenylpropanal. In contrast to saturated carboxylates saturated aldehydes can be dehydrogenated to alpha,beta-unsaturated aldehydes (enals) by enoate reductase in the presence of electron acceptors such as oxygen or dichlorophenol indophenol. Under these conditions enoate reductase shows in the presence of oxygen a surprisingly high half life (greater than 20 h) as compared to that which is observed when the enzyme was used as a reductase with NADH in the presence of oxygen. In this case the enzyme is inactivated within a few minutes.

ChemInform Abstract: A Facile Synthesis of Optically Pure L‐Armentomycin and Its D‐Isomer. Highly Enantioselective Reduction of the C‐C Double Bond of Methyl (E)‐ and (Z)‐2,4,4‐Trichloro‐2‐butenoate by Using Baker′s Yeast.

AbstractThe trichlorobutenoate E‐(I) is selectively hydrogenated with baker's yeast to produce the saturated carboxylate (R)‐(II) after esterification.

Micelle formation and terminal double bonds in sodium carboxylates

The effect of terminal unsaturation on the CMC values of sodium 11-dodecenoate and sodium 12-tridecenoate have been probed using conductance and 23 Na NMR. The results suggest that addition of a terminal double bond has the same effect on the CMC of the corresponding saturated sodium carboxylate as the removal of 1.1 CH 2 units. Our results confirm that the previous study of the above effect, observed for sodium 10-undecenoate, is probably a general one.

Purification and some properties of a hitherto-unknown enzyme reducing the carbon-carbon double bond of alpha, beta-unsaturated carboxylate anions.

2-Enoate-reductase, a previously unknown soluble enzyme is present in Clostridium kluyveri and another Clostridium species growing on (E)-2-butenoate. From the latter the reductase was purified 88-fold with an overall yield up to 74%. The enzyme was pure as judged by polyacrylamide gel electrophoresis with and without sodium dodecyl sulphate as well as by isoelectric focusing. The purification of the enzyme was performed in the presence of (E)-2-methyl-2-butenoate as substrate to keep the enzyme in the oxidized state and under anaerobic conditions. The purification procedure included an ammonium sulphate precipitation, chromatography on DEAE-Sepharose CL-6B, hydroxylapatite and Sepharose CL-6B. The enzyme reduces different alpha,beta-unsaturated carboxylate anions such as (E)-2-butenoate, (E)-2-methyl-2-butenoate, (E)-cinnamate and probably many others in a NADH-dependent reaction to the saturated carboxylate anions. Fumarate, 3-phenyl-2-propinate, 2-enoyl-methyl and CoA esters proved not to be substrates for the purified reductase. NADPH does not act as an electron donor. The enzyme was shown to have a molecular weight of about 450,000 by gel chromatography. It consists of subunits with a molecular weight of 78,000. Per subunit about 1 FAD, 3.5--3.8 atoms of iron and 4.0 labile sulphur atoms have been found indicating a conjugated iron-sulphur flavo-protein. Copper could not be detected. The isoelectric point was 8.4. As shown by absorption spectroscopy the enzyme can be reduced by NADH and reoxidized with dichloroindophenol, hexacyanoferrate III, oxygen and substrates. Addition of 8 mol p-hydroxymercuribenzoate to 1 mol subunit completely destroyed the activity of the reductase. So far no physiological role of the enzyme is known.