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Catalytic Transformation of Triglycerides to Biodiesel with SiO2-SO3H and Quaternary Ammonium Salts in Toluene or DMSO. Molecules 2022; 27:molecules27030953. [PMID: 35164218 PMCID: PMC8840453 DOI: 10.3390/molecules27030953] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Revised: 01/20/2022] [Accepted: 01/21/2022] [Indexed: 12/01/2022] Open
Abstract
SiO2-SO3H, with a surface area of 115 m2·g−1, pore volumes of 0.38 cm3·g−1 and 1.32 mmol H+/g, was used as a transesterification catalyst. Triglycerides of waste cooking oil reacted with methanol in refluxing toluene to yield mixtures of diglycerides, monoglycerides and fatty acid methyl esters (FAMEs) in the presence of 20% (w/w) catalyst/oil using the hydrophilic sulfonated silica (SiO2-SO3H) catalyst alone or with the addition of 10% (w/w) co-catalyst/oil [(Bun4N)(BF4) or Aliquat 336]. The addition of the ammonium salts to the catalyst lead to a decrease in the amounts of diglycerides in the products, but the concentrations of monoglycerides increased. Mixtures of (Bun4N)(BF4)/catalyst were superior to catalyst alone or Aliquat 336/catalyst for promoting the production of mixtures with high concentrations of FAMEs. The same experiments were repeated using DMSO as the solvent. The use of the more polar solvent resulted in excellent conversion of the triglycerides to FAME esters with all three-catalyst media. A simplified mechanism is presented to account for the experimental results.
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2
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Dehydration of D-fructose to 5-hydroxymethyl-2-furfural in DMSO using a hydrophilic sulfonated silica catalyst in a process promoted by microwave irradiation. Sci Rep 2021; 11:1919. [PMID: 33479324 PMCID: PMC7820282 DOI: 10.1038/s41598-020-80285-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Accepted: 12/14/2020] [Indexed: 11/09/2022] Open
Abstract
SiO2-SO3H, with a surface area of 115 m2/g, pore volumes of 0.38 cm3g-1 and 1.32 mmol H+/g, was used as a 10% w/w catalyst for the preparation of 5-hydroxymethyl-2-furfural (HMF) from fructose. A conversion of 100% was achieved in a microwave reactor during 10 min at 150 °C in DMSO, with 100% selectivity for HMF, at a molar ratio of fructose: DMSO equal to 1:56. The catalyst could be re-used three times.
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Synthesis of Phenyl Esters Using SiO₂-SO₃H Catalyst in Conventional Heating and Microwave-Irradiated Esterification Processes. JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY 2019; 19:3663-3668. [PMID: 30744803 DOI: 10.1166/jnn.2019.16104] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
A SiO₂-SO₃H amorphous catalyst containing a small surface area of 115.0 m²g-1 and 1.32 mmol H+/g was prepared from fine construction sand and sodium carbonate and sulfonated with H₂SO₄. In a 10% (w/w) basis, it is very efficient for catalyzing the esterification of carboxylic acids with phenol. The reaction processes were performed using conventional heating and under microwave irradiation. The yields were higher in the microwave-irradiated esterification. The catalyst could be used for three esterification sequences in both processes.
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Oxygenated biofuels: Synthesis of fatty acid solketal esters with a mixture of sulfonated silica and (Bu4N)(BF4) catalyst. CATAL COMMUN 2019. [DOI: 10.1016/j.catcom.2018.12.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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The preparation of benzyl esters using stoichiometric niobium (V) chloride versus niobium grafted SiO 2 catalyst: A comparison study. Heliyon 2018; 4:e00571. [PMID: 29862338 PMCID: PMC5968132 DOI: 10.1016/j.heliyon.2018.e00571] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Revised: 01/30/2018] [Accepted: 03/07/2018] [Indexed: 11/18/2022] Open
Abstract
Two solvent free methods of a one-to-one alcohol/acid mol ratio synthesis of benzyl esters of the formic, acetic, benzoic, salicylic, nicotinic, and oxalic acids are described. The stoichiometric reactions used 1.5 mol ratio solid NbCl5 as the reagent and required from two to three hours for completion at room temperature; for the catalytic processes, NbCl5 was grafted directly, at room temperature, onto a silica gel of specific area of 507 m2g−1, produced from construction sand and sodium carbonate, forming a 5.4% Nb w/w SiO2-Nb gel with a specific area of 412 m2g−1. At 10% w/w catalyst/alcohol ratio, this SiO2-Nb catalyst gave similarly very good yields but required from 6 to 9 hours at the reflux temperature of the slurry. The catalyst could be re-used three times.
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Effects of alternate day feeding of dried distiller's grains plus solubles in forage-fed steers on intake, ruminal fermentation and passage rates, and serum nonesterified fatty acid. J Anim Sci 2016; 93:3959-68. [PMID: 26440176 DOI: 10.2527/jas.2015-9070] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Four ruminally and duodenally cannulated Holstein steers (BW = 449 ± 7.3 kg) were used to examine the effects of feeding either dried distiller's grains plus solubles (DG) or grass hay on alternate days (every other day) on intake, ruminal fermentation and passage rates, and serum NEFA in forage-fed steers. Steers were assigned to 1 of 4 dietary treatments in a 4 × 4 Latin square: 1) only hay (CON), 2) hay and 0.4% of BW as DG DM daily (DG7), 3) hay daily and 0.8% BW DG every other day (DG2), and 4) alternate day feeding of hay and 0.8% of BW as DG (DGA). Treatment periods consisted of 13 d of adaptation and 8 d of collecting digesta and blood. Over the entire collection period, DMI was decreased ( = 0.004) for DGA compared with other treatments (13.0 ± 0.8, 12.7 ± 0.8, 13.3 ± 0.8, and 10.9 ± 0.8 kg/d for CON, DG7, DG2, and DGA, respectively). Immediately after feeding on days supplement was fed to DG2 and DGA (supplemented days [SUP]), ruminal pH of DGA was less than other treatments but by the end of the day was greater than other treatments (treatment × time, < 0.001). At feeding time on nonsupplemented days (NSUP), ruminal pH of DGA steers was greater than other treatments but was similar (treatment × time, < 0.001) to DG2 and CON by 5 h after feeding. Total concentrations of VFA were similar ( = 0.09) among treatments on SUP; however, on NSUP, total VFA concentrations were least in DGA from feeding until 4 h after feeding (treatment × time, = 0.02). No differences ( ≥ 0.06) were observed among treatments for apparent ruminal, total intestinal, and total tract DM, OM, or CP digestibility. There were no differences ( = 0.36) in serum NEFA among treatments on SUP; however, on NSUP, steers fed DGA (209.5 ± 12.7 m) had greater ( < 0.01) NEFA compared with other treatments (84.4 ± 12.7, 88.0 ± 12.7, and 77.7 ± 12.7 m for CON, DG7, and DG2, respectively). The DGA feeding strategy influenced DMI and ruminal kinetics and circulating NEFA without impacting total tract digestibility.
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Superiority of enoxaparin over heparin in combination with a GPIIb/IIIa receptor antagonist during coronary thrombolysis in dogs. Thromb Res 2001; 102:261-71. [PMID: 11369420 DOI: 10.1016/s0049-3848(01)00242-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
It is known that a low-molecular-weight heparin (LMWH) is more effective than unfractionated heparin in unstable angina/non-Q-wave myocardial infarction (UA/NQMI) and the platelet GPIIb/IIIa receptors play an important role in acute myocardial infarction (AMI). Therefore, enoxaparin might have a similar advantage over heparin when used with a GPIIb/IIIa antagonist (RPR109891) in coronary thrombolysis. After induction of coronary thrombosis in anesthetized dogs, infusion of saline, enoxaparin, heparin, RPR109891, enoxaparin+RPR109891, or heparin+RPR109891 was initiated followed 15 min later by recombinant tissue plasminogen activator (rt-PA). The incidence of reperfusion in the enoxaparin+RPR109891- and the heparin+RPR109891-treated groups was similar, but time to reperfusion tended to be shorter for enoxaparin versus heparin. Only 43% of the vessels reoccluded in the enoxaparin+RPR109891 group, compared to 100% vessels in the heparin+RPR109891 group. Enoxaparin+RPR109891 maintained flow for a significantly longer time compared to saline, enoxaparin, heparin, and heparin+RPR109891. Enoxaparin+RPR109891 and heparin+RPR109891 increased the template bleeding time by 2- and 3-fold and activated partial thromboplastin time (APTT) by 1.3- and 3-fold, respectively. These data suggest that enoxaparin is more effective and potentially safer than heparin when combined with a GPIIb/IIIa receptor antagonist during rt-PA-induced coronary thrombolysis.
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Abstract
Involved in the coagulation cascade, factor Xa (FXa) is a serine protease which has received great interest as a potential target for the development of new antithrombotics. Although there is a great wealth of structural data on thrombin complexes, few structures of ligand/FXa complexes have been reported, presumably because of the difficulty in growing crystals. Reproducible crystallization conditions for human des-Gla1-45 coagulation FXa have been found. This has led to an improvement in the diffraction quality of the crystals (about 2.1 A) when compared to the previously reported forms (2.3-2.8 A) thus providing a suitable platform for a structure-based drug design approach. A series of crystal structures of noncovalent inhibitors complexed with FXa have been determined, three of which are presented herein. These include compounds containing the benzamidine moiety and surrogates of the basic group. The benzamidine-containing compound binds in a canonical fashion typical of synthetic serine protease inhibitors. On the contrary, molecules that contain surrogates of the benzamidine group do not make direct hydrogen-bonding interactions with the carboxylate of Asp189 at the bottom of the S1 pocket. The structural data provide a likely explanation for the specificity of these inhibitors and a great aid in the design of bioavailable potent FXa inhibitors.
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Efeitos estéricos e eletrônicos de substituintes alquilas em catalisadores titanocênicos solúveis na polimerização sindioespecífica de estireno. POLIMEROS 1999. [DOI: 10.1590/s0104-14281999000400019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Titanocenos são catalisadores solúveis conhecidos para a polimerisação estereoespecífica de olefinas pró-quirais como o estireno. Nesse trabalho descrevemos as relações entre as características do poliestireno e a estrutura do precursor do catalisador, de fato aqueles da família (RCp)2TiCl2 (R = H, etila, iso-propila, n-propila, sec-butila, n-butila, iso-amila e ciclohexila). Todos os catalisadores são ativos para a produção de poliestireno acima de zero graus centígrados. A sindiotaticidade dos polímeros são dependentes da cadeia lateral dos anéis aromáticos do titanoceno e da temperatura da polimerização. A relação entre os fatores estéricos e eletrônicos do precursor do catalisador e os produtos de polimerização são apresentados e discutidos.
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Growth and differentiation of bone marrow hematopoietic cells in mice bearing Ehrlich ascite tumor and treated with Dicyclopentadienildichlorotitanium (IV). INTERNATIONAL JOURNAL OF IMMUNOPHARMACOLOGY 1998; 20:573-81. [PMID: 9839661 DOI: 10.1016/s0192-0561(98)00058-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
In this work we have investigated the growth and differentiation of bone marrow stem cells in mice bearing Ehrlich ascites tumor and treated with three dose-regimens of Dicyclopentadienyldichlorotitanium (IV) (DDCT). We also studied the presence of colony stimulating factors in the serum of DDCT-treated animals, as well as the effects of the drug on the survival of the tumor-bearing mice. The results demonstrated that the myelosuppression developed in the tumor-bearing animals is prevented by the administration of 1, 2 or 3 doses of 15 mg/kg DDCT. In the treatment with three doses, however, 23% of the animals died. Moreover, DDCT treatment in normal animals resulted in increased numbers of CFU-GM. We observed the presence of stimulating factors in the serum of drug-treated animals which induced the growth and differentiation of bone marrow progenitor cells from normal animals in vitro. On the other hand, in vitro addition of the drug to these cultures had no effect. Thus, we conclude that the drug protects against the myelosuppression induced by the tumor and that this protection may be related to an indirect action of the drug.
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Abstract
The integrin receptor recognition sequence Arg-Gly-Asp was successfully used as a template from which to develop a series of potent, selective, orally active, peptide-based fibrinogen receptor antagonists with a long duration of action. Simple modifications centered on the Arg and Gly residues quickly led to a modified peptide (1) with significantly enhanced ability to inhibit in vitro platelet aggregation. Substitution of the guanidino group in 1 by piperidine provided 3, which showed not only a further increase in potency but also a modest degree of oral efficacy. Finally, exploration of the nature of the C-terminal amino acid, with respect to its side-chain functionality and the carboxy terminus, yielded a group of molecules that showed excellent in vitro potency for inhibiting platelet aggregation, excellent integrin selectivity, a high level of oral efficacy, and an extended duration of action.
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Identification and initial structure-activity relationships of a novel class of nonpeptide inhibitors of blood coagulation factor Xa. J Med Chem 1998; 41:437-50. [PMID: 9484495 DOI: 10.1021/jm970482y] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The discovery and some of the basic structure-activity relationships of a series of novel nonpeptide inhibitors of blood coagulation Factor Xa is described. These inhibitors are functionalized beta-alanines, exemplified by 2a. Docking experiments placing 2a in the active site of Factor Xa implied that the most expeditious route to enhancing in vitro potency was to modify the group occupying the S3 site of the enzyme. Increasing the hydrophobic contacts between the inhibitor and the enzyme in this region led to 8, which has served as the prototype for this series. In addition, an enantioselective synthesis of these substituted beta-alanines was also developed.
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Conformationally flexible platelet aggregation inhibitors based on the tetrapeptide Arg-Gly-Asp-Arg. Eur J Med Chem 1997. [DOI: 10.1016/s0223-5234(99)80069-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Abstract
RG13965, a pseudotetrapeptide analogue of Arg-Gly-Asp (RGD), inhibited collagen-induced dog, monkey, human, hamster, mouse, and pig platelet aggregation in vitro with IC50 values of 3.7, 4.6, 6.3, 126, 136 and 1600 microM, respectively. RG13965 (3, 10, and 30 mg/kg, i.v.) decreased the incidence of collagen/epinephrine-induced thrombosis in mice from 90% in untreated animals to 63, 37, and 0%, respectively. In hamsters, RG13965 (10 and 30 mg/kg, i.v.) prolonged the time required for formation of a hemostatic plug in severed mesenteric arteries by 1.6- and 3.6-fold, respectively. In a canine model of repetitive platelet thrombus formation in the coronary artery, RG13965 (0.1, 0.3, and 1 mg/kg, i.v.) reversibly inhibited cyclic flow reductions (CFRs) and inhibited ADP-induced ex vivo platelet aggregation by 29, 57, and 77%, respectively. RG13965 (1 mg/kg) completely inhibited CFRs for at least 40 min. Platelet count was not altered at any dose and template bleeding time was prolonged modestly (1.8-fold) at only the highest dose. RG13965 dose-dependently and reversibly inhibited thrombus formation at doses which did not completely inhibit ex vivo platelet aggregation and only modestly prolonged template bleeding time.
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Synthesis and solid-state structural characterization of di-μ-azido-bis[{azido(N, N-diethylethylenediamine)}copper(II)]. TRANSIT METAL CHEM 1989. [DOI: 10.1007/bf01129758] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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18
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Time differential perturbed angular correlation (TDPAC) study of some hafnium glycolate complexes. Polyhedron 1988. [DOI: 10.1016/s0277-5387(00)81797-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Bilateral anomalous anterior cerebral artery and infraoptic aneurysm. AJNR Am J Neuroradiol 1987; 8:1142-3. [PMID: 3120543 PMCID: PMC8332359] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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Ready formation of phosphonate complexes of rhodium and iridium from [M(P(OMe3)5]Cl compounds (M = Rh, Ir). Differences between reactions of dihydrogen with [Mp(O)(OMe)2(P(OMe)3)4] complexes (M = Co, Rh, Ir), including facile hydrogenolysis of a rhodiumphosphorus bond. J Organomet Chem 1986. [DOI: 10.1016/0022-328x(86)80155-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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22
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Synthesis and variable temperature 31P NMR spectra of the cobalt, rhodium and iridium complexes [M(P(O)(OMe)2)(P(OMe)3)4] (M = Co, Rh, Ir). J Organomet Chem 1986. [DOI: 10.1016/0022-328x(86)80064-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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23
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Syntheses of η1- and η2-phospha-alkene-transition metal complexes and the first examples of complexes containing only ligated phospha-alkenes and phospha-alkynes. ACTA ACUST UNITED AC 1983. [DOI: 10.1039/c39830000930] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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