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41.
The binding of a homologous series of n-alkyltrimethyl ammonium bromides with Jack bean urease (JBU) have been studied previously. It has been suggested that both electrostatic and hydrophobic interactions are involved in the formation of surfactant-protein complexes, but there is not any quantities analyzing method for resolution of their contributions in the process. In the present study, at first, the intrinsic Gibbs free energy of binding, ΔGb,ν, has been calculated for these systems and the trend of variation for both binding sets have been interpreted on basis of cooperativity and hydrophobicity of surfactants. Subsequently, a novel approach has been introduced for estimation of electrostatic and hydrophobic interactions in ΔGb,ν, by considering of this fact that ΔGb,ν is the summation of electrostatic, ΔGb,ν(ele), and hydrophobic, ΔGb,ν(hyd), parts and considering this fact that just ΔGb,ν(hyd) is a function of hydrocarbon tail length of surfactant (Cn). The results represents the higher positive rule of electrostatic interactions in binding affinity of first set and inhibiting rule of this interaction in the second binding set. The predominate driving force in the second binding set is entropy statistical effect, which arises from numerous number of binding sites in this set. A binding mechanism on basis of structural changes in JBU due to its interaction with cationic surfactants has also been proposed. 相似文献
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Navabeh Nami Masoumeh Hosseinzadeh Nasrin Nami Mina Haghdadi 《Phosphorus, sulfur, and silicon and the related elements》2013,188(11):2846-2855
Refluxing dimethyl acetylenedicarboxylate (DMAD) or 1,2-dibenzoylacetylene with isatin-3-thiosemicarbazone or isatin-3-thiocarbohydrazone in methanol produced 3-substituted oxindoles in good yields. Reaction of equimolecular amounts of 5,6-diamino-urasil-solfate, trans-(1R,2R)-diaminocyclohexane, and 3,4-diamino-1,2,4-triazol-5-methyl hydrochlorid with isatin in ethanol (85%) afforded tetracyclic ring systems and ring-opened products in mild reaction conditions. 相似文献
44.
Polypyrrole/Fe3O4/CNT as a recyclable and highly efficient catalyst for one‐pot three‐component synthesis of pyran derivatives
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Polypyrrole (PPY)/Fe3O4/CNT has been synthesized and characterized by FT‐IR, TEM and SEM techniques and its catalytic activity has been evaluated in the synthesis of several series of pyran derivatives. Tetrahydrobenzo[b]pyranes, 4H‐pyran‐3‐carboxylates, 4H,5H‐pyrano[3,2‐c]chromenes and dihydropyrano[2,3‐c]pyrazoles have been successfully prepared from one‐pot three‐component condensation of aldehyde, malononitrile and active methylene‐containing compounds (dimedone /ethyl acetoacetate/4‐hydroxycoumarin/3‐methyl‐2‐pyrazoline‐5‐one) using PPY/Fe3O4/CNT as a new and reusable heterogeneous catalyst. The present method offer several advantages such as; high yields of products, short reaction times, easy work‐up procedure and easy separation of the catalyst from the reaction mixture due to its magnetic character. Furthermore, chemoselective synthesis of bis‐benzo[b]pyran from terephthalaldehyde can be achieved by this method. 相似文献
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Farhad Gharagheizi Mohammad Hossein Keshavarz Poorandokht Ilani-Kashkouli Nasrin Farahani Kaniki Tumba 《Journal of Thermal Analysis and Calorimetry》2013,114(3):1363-1382
Glass-transition temperature (T g) of ionic liquids (ILs) plays a key role in assessment of their potential for electrolyte application purposes. In this communication, a new group contribution model is presented for the prediction of the T g of 1,3-dialkylimidazolium, a class of ILs, which has great potentialities to serve as electrolyte. To develop this model, the contribution of ILs’ anions and cations is separately considered. This simple model shows a low average relative deviation of 1.94 % for a data set including 109 experimental glass-transition temperature. 相似文献
46.
Alcohols and Phenols are protected efficiently with dihydropyran(DHP) in the presence of catalytic amounts of zirconium tetrachloride in dichloromethane. Deprotection of THP-ethers is also afforded in a methanolic solution at room temperature. 相似文献
47.
Akhundi Anise Naseri Amene Abdollahi Nasrin Samadi Morasae Moshfegh Alireza 《Research on Chemical Intermediates》2022,48(5):1793-1811
Research on Chemical Intermediates - Worldwide energy and environmental issues are forcing researchers to develop a green approach to produce a clean energy. However, traditional methods in... 相似文献
48.
An efficient and versatile procedure for the acetylation of alcohols and phenols using acetic anhydride in the presence of a catalytic amount of polyvinylpolypyrrolidoniume tribromide has been successfully developed.Primary,secondary,and tertiary alcohols,as well as a selection of the phenolic compounds,have been successfully acetylated according to this procedure,with good to high yields being achieved over short reaction times. 相似文献
49.
A facile and efficient synthesis of 1,5‐benzodiazepines with an arylsulfonamido substituent at C(3) is described. 1,5‐Benzodiazepine, derived from the condensation of benzene‐1,2‐diamine and diketene, reacts with an arylsulfonyl isocyanate via an enamine intermediate to produce the title compounds of potential synthetic and pharmacological interest in good yields (Scheme 1). In addition, reaction of benzene‐1,2‐diamine and diketene in the presence of benzoyl isothiocyanate leads to N‐[2‐(3‐benzoylthioureido)aryl]‐3‐oxobutanamide derivatives (Scheme 2). This reaction proceeds via an imine intermediate and ring opening of diazepine. The structures were corroborated spectroscopically (IR, 1H‐ and 13C‐NMR, and EI‐MS) and by elemental analyses. A plausible mechanism for this type of cyclization is proposed (Scheme 3). 相似文献
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Optimization Letters - In the original publication of the article, the name of the corresponding author was incorrectly published as “Amir Ahamdi”. 相似文献