جستجوی مقالات مرتبط با کلیدواژه « Alcohol » در نشریات گروه « شیمی »
تکرار جستجوی کلیدواژه «Alcohol» در نشریات گروه «علوم پایه»-
Employment of the magnetic nano-catalyst Fe3O4@SiO2@CS@ PO(OH)2/Cu(II) for the amination of alcoholsIn this research study, the Fe3O4@SiO2@CS@ PO(OH)2/Cu(II) core-shell nanoparticle serves as a highly effective magnetic catalyst. Its purpose is to efficiently convert a variety of alcohols, whether they contain electron-donating or electron-withdrawing groups, into their corresponding amine derivatives. Benzylamine and ammonia were employed as the amination agents. The optimization process studied various factors, including the presence and kind of a base, reaction temperature, time of reaction, type of transition metal, and amount of catalyst to identify the most favorable parameters. The optimal conditions were observed when using 0.3 mmol of catalyst liganded to Cu(II) under reflux conditions for a duration of 5-24 h corresponding to the substrate in the presence of K2CO3. The results of the study revealed that electron-donating groups have a positive impact on the reaction rate, whereas electron-withdrawing groups, such as nitro, negatively influence the overall yield. Additionally, this reaction process displayed remarkable efficiency. It offers exceptional practicality in organic chemistry and industrial applications, primarily due to the ease of separating the catalyst using an external magnetic field, its stability, and its ability to be reused multiple times.Keywords: AMINATION, Magnetic nanocatalyst, Core-shell nanoparticle, Catalyst optimization, Alcohol}
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فعالیت کاتالیستی CuPF6 برای اکسایش گزینشی الکل های بنزیلی به آلدهیدها مربوطه با استفاده از پراستر ترشیوبوتیل 4 نیتروپربنزوات به عنوان عامل اکساینده بررسی شد و اکسایش الکل های بنزیلی به آلدهیدهای متناظر با انتخاب گری بالا انجام شد. تبدیل کامل همه الکل های بنزیلی به آلدهیدهای مربوطه در یک دوره واکنش کوتاه در 40 درجه سلسیوس به دست آمد. عملکرد اکسایش کاتالیستی وابسته به اثرهای الکترونی و فضایی استخلاف ها قرار گرفته بر روی حلقه فنیل می باشد. استخلاف های الکترون دهنده در موقعیت پارا و متا سبب افزایش بازده و کاهش زمان واکنش می شود (اثرهای الکترونی). هم چنین گروه ها اعم از الکترون دهنده و کشنده در موقعیت اورتو سبب کاهش بازده و افزایش زمان واکنش می شود (اثرهای فضایی). اکسایش الکل های بنزیلی نوع دوم 1 فنیل اتانول و 1 ایندانول به کتون ه ای مربوطه با استفاده از پراستر در مجاورت کاتالیست CuPF6 طی 5 ساعت به ترتیب با بازده 15 و 23 درصد صورت گرفت. الکل های غیر بنزیلی و آلیلی نوع اول و دوم در سامانه اکسایشی معرفی شده اکسید نمی شوند. بنابراین سامانه اکسایشی پراستر در مجاورت کاتالیست CuPF6 هم از نظر نوع ماده اولیه الکل های بنزیلی برای اکسایش و هم از نظر نوع فراورده به دست آمده آلدهیدی گزینشی عمل می نماید.کلید واژگان: اکسایش گزینشی, الکل, آلدهید, پراستر, CuPF6}The catalytic activity of CuPF6 has been studied for the selective oxidation of benzylic alcohols to the corresponding aldehydes using tert-butyl p-nitrobenzoperoxoate an oxidizing agent. This system showed excellent catalytic activity for the oxidation of benzylic alcohols to the corresponding aldehydes with high selectivity. The complete conversion of the benzylic alcohols to the corresponding aldehydes is achieved within a short reaction period at 40 °C. The catalytic performance is obtained to be dependent on the electronic and steric effects of the substituents present on the phenyl ring. Electron donating groups on the para and meta position of phenyl ring increase the efficiency and reduce the reaction time (electronic effects). Also, different types of groups, such as donor and withdraw, on the ortho position of phenyl ring reduce the reaction efficiency and increase reaction time (steric effects). The oxidation of 1-phenylethanol and 1-indanol to the corresponding ketones was performed using a tert-butyl p-nitrobenzoperoxoate in the presence of CuPF6 for 5 hours, with a yield of 15% and 23% respectively. Oxidation of non-benzylic alcohols could not be oxidized to the corresponding aldehydes or ketones even after 24 h. Thus, tert-butyl p-nitrobenzoperoxoate was found to act as a highly chemoselective oxidant for the oxidation of primary and secondary benzylic alcohols in the presence of CuPF6 as a catalyst.Keywords: Selective oxidation, Alcohol, Aldehyde, Perster, CuPF6}
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In this study, the nanoporous γ-alumina catalysts were prepared by the sol-gel method using hydrolysis of aluminum isopropoxide in the presence of TX-100 or gelatin/TX-100 mixture. Catalysts were characterized by XRD, FT-IR, TEM, BET-BJH and N2 adsorption-desorption isotherms. To investigate reactivity and selectivity of the synthesized catalysts, dehydration reaction of 2-octanol was carried out in a plug flow vertical reactor at 200 °C. The main products of elimination reaction were 1-octene, 3-octene, cis- and trans-2-octene, which were identified by GC-MS. The reaction conversion and yield of the products were determined using GC. The prepared catalysts had nanometer-sized pores, high surface area and large pore volume. Their catalytic activity for dehydration of 2-octanol was higher than non-porous γ-alumina catalysts. These compounds could be used as effective catalysts for dehydration of alcohols.Keywords: γ-Alumina, Nanoporous, Triton X-100, Gelatin, Dehydration, Alcohol, Alkene}
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The influence of NaNO2, HNO3 and H2SO4 on the structure and morphology of gamma-alumina was investigated by XRD, BET, SEM and FT-IR spectroscopy. Selected amounts of NaNO2, HNO3 and H2SO4 were added to a solution of aluminum isopropoxide (as a precursor for the boehmite synthesis). The boehmite samples were calcined at 350 and 600 ℃ to form the semi-crystalline high surface area gamma-Al2O3. The reactivity and selectivity of the modified gamma-alumina catalysts were examined using dehydration reaction of 2-octanol. There was a good correlation between reactivity, selectivity and the amounts (and type) of the modification. The dominant product was cis-2-octene for all of the catalysts. Low conversion and high selectivity were obtained for dehydration of 2-octanol over alumina modified with NaNO2. High conversion, low selectivity and excessive isomerization were found for gamma-alumina catalyst modified with H2SO4.
Keywords: Alumina, Dehydration, Alcohol, reactivity, Selectivity} -
In this article, the catalytic activity of bis[2-(p-tolyliminomethyl)phenolato] copper(II) complex was studied, for the first time, in the oxidation of various primary and secondary alcohols to the corresponding aldehydes or ketones. The effect of different solvent was studied in the oxidation of benzyl alcohol and methanol was chosen as the reaction medium. Also the effect of different oxidants such as H2O2, urea-H2O2 (UHP), NaOCl, tert- BuOOH (TBHP) and NaIO4 was studied in the oxidation of benzyl alcohol and H2O2 was selected as oxygen donor. In this catalytic system, oxidation of benzyl alcohol required 4 mol% of catalyst for completion and with increasing the reaction temperature to 60 °C, the highest oxidation yield was observed. Results showed that this homogeneous catalyst, exhibited good catalytic activity in the selective oxidation of various alcohols with hydrogen peroxide and gave the corresponding aldehyde without further oxidation to carboxylic acids in good to excellent yields (56-95%).
Keywords: Schiff base, Copper(II) complex, Homogeneous catalyst, alcohol, oxidation, Hydrogen peroxide} -
Application of SiO2@FeSO4 nanocomposite as a new nanocatalyst in reduction area was investigated. Carboxylic acid simple and convenient reduction to alcohol by 0.75 mol of the nanocomposite, 3 mol sodium borohydride (NaBH4) as reduction reagent under a solvent-free condition at 30-65 min. The reaction happens in two stages - first to form an aldehyde and then a primary alcohol. Because sodium aluminum hydride reacts rapidly with aldehydes, it is impossible to stop at the halfway stage. The method does not require an anhydrous solvent, does not involve a hazardous reagent has somewhat different selectivity than techniques in general use, and may sometimes be the method of choice.Keywords: SiO2@FeSO4, Carboxylic acid, Alcohol, NaBH4, Solvent-free}
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An efficient method is described for the mild and rapid tetrahydropyranylation of alcohols and phenols using a catalytic amount of N-chlorosaccharin (1 mol %) and 3, 4-dihydro-2H-pyran under solvent-free condition at room temperature. Benzylic alcohols and phenols containing electron withdrawing or donating groups in various positions of phenyl ring, cinamyl alcohol, primary, secondary, tertiary as well as cyclic alcohols are converted to their corresponding tetrahydropyranyl ethers in short reaction times and in excellent yields via the present method. Primary benzylic alcohols in the presence of secondary ones and also primary or secondary aliphatic alcohols in the presence of tertiary ones can be efficiently tetrahydropyranylated with excellent selectivity via this method.Keywords: Alcohol, Phenol, Tetrahydropyranylation, N, Chlorosaccharin}
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در این مقاله یک روش موثر و کارا برای تهیه کرباماتهای نوع اول از الکلها و فنولها با استفاده از سدیم سیانات و نیز محافظت آمینها بصورت بوتوکسی کربونیل در مجاورت سولفوریک اسید جذب شده روی سیلیکاژل توصیف می شود واکنشها در شرایط بدون حلال انجام شده است. این روش ها ساده، موثر و دوستدار محیط زیست بوده و از مزیت بازده خوب تا عالی برخوردار می باشند.
کلید واژگان: کرباماتهای نوع اول, آمین, محافطت از طریق ترشیو بوتوکسی کربونیل دار کردن, الکل, سدیم سیانات}An efficient and mild method for the preparation of primary carbamate from alcohols and phenols using sodium cyanate and Boc-protection of amine in the presence of H2SO4-Silica was demonstrated. The reactions were carried out under solvent free conditions. These methods are simple، effective and environmentally friendly and have the advantage of good to excellent yields.Keywords: Primary Carbamate, Amine, Boc, protection, Alcohol, Sodium Cyanate} -
In this study, the adsorption behavior of the primary, secondary and tertiary alcohols over nanoscale (1 0 0) surface of defect spinel γ-alumina was investigated with the aid of density functional theory (DFT) at BLYP/DNP level of calculation. The influence of different substituents including alkyl, cycloalkyl, allyl and aryl were analyzed for free and adsorbed alcohols to shed light the adsorption selectivity of these compounds over γ-alumina surface. These results indicate that more branches at a position of alcohol favor the adsorption, while a decrease in adsorption energy is achieved for the alcohols containing the substituents at the β position. The tertiary alcohols are adsorbed over the surface stronger than secondary and primary alcohols. Alcohols with larger alkyl chains have greater adsorption energies. Also the aryl alcohols are adsorbed over the surface better than the alkyl and allyl moieties.Keywords: γ-Alumina, Alcohol, Molecular adsorption, DFT}
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روشی آسان و ساده برای اکسایش الکلها با استفاده از آلومینیوم نیترات نه آبه (Al(NO3)3.9H2O) به عنوان اکسنده، بدون هیچ گونه ماده کمکی دیگر گزارش شده است. واکنشها در شرایط بدون حلال و در دمای C 80 با بازده خوب و یا عالی انجام می پذیرند.
کلید واژگان: الکل, اکسایش, آلومینیوم نیترات نه آبه, شرایط بدون حلال}A simple and easy method has been reported for the oxidation of alcohols using aluminum nitrate nine hydrate (Al(NO3) 3. 9H2O) as an oxidant، without any auxiliary reagent. Reactions were accomplished in solvent-free conditions with excellent or good yields at 80 C.Keywords: Alcohol, Oxidation, Aluminum nitrate nine hydrate, Solvent, free conditions} -
The fact that the properties of a molecule are tightly connected to its structural characteristics is one of the fundamental concepts in chemistry. In this connection, graph theory has been successfully applied in developing some relationships between topological indices and some thermodynamic properties. So , a novel method for computing the new descriptors to construct a quantitative relation between structure and properties is presented. At first, a brief review on the classical graph theories introduced and, then, the link with molecular similarity is drawn. In the applications section, molecular topological indices are calculated. Afterwards, the molecular descriptors, that include the necessary structural information for properly describtion of system are employed to derive a numerical correlation with thermodynamic properties. Finally, some useful topological indices for examination of the structure-property relationship are presented. In addition, the relationship between the Randic, Wiener, Hosoya , Balaban and Schultz indices and Harary numbers and Distance matrix to the enthalpies of formation, heat capacities, (Cp) , enthalpies of combustion, enthalpies of vaporization and normal boiling points for normal alcohols is established.Keywords: thermodynamic properties, Topological indices, Alcohol, Graph theory, QSAR, QSPR}
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