در هنگام جستجو کلمه در قسمت عنوان میتوانید کلمات مورد جستجو را با کاراکتر (-) جدا کنید.
کاربرد نوع شرط:
- جایگاه : پژوهشی
- مجله: Chemical Methodologies
- نوع مقاله: Journal Article
- کلمات کلیدی: Ultrasonic and microwave irradiation,Benzamide/ SO2Cl2,Rate accelerations
- چکیده:
- چکیده انگلیسی: Benzamide/ Sulfuryl Chloride (SO2Cl2) reagent has been developed as a Vilsmeier- Haack(VH) reagent for benzoylation of aromatic compounds by using the conventional and ultrasonic sonication (US), and microwave (MW) conditions. Benzoylation is much more competent and faster than the analogous VH ((Benzamide/ POCl3) or (Benzamide/ SOCl2)) reagents and afforded benzoyl derivatives in good yields. Reaction times are moderately less than those observed with [Benzamide/ POCl3] and (Benzamide/ SOCl2) reagents. Reaction times are far less in microwave assisted (MWAR) reactions than ultrasonically assisted (USAS) reactions , which in turn are less than the conventional method with a decreasing trend: MWAR (seconds) << Sonication (minutes) << conventional (hrs). The highly remarkable rate accelerations in MW assisted reactions are attributed to the bulk activation of the molecules; while US assisted reactions could be accounted for cavitation effects.
- انتشار مقاله: 10-06-1396
- نویسندگان: Marri Venkateswarlu,Mukka Satish Kumar,Chinna Rajanna Kamatala,Purugula Venkanna,Pondichery Kuppuswamy Saiprakash
- مشاهده
- جایگاه : پژوهشی
- مجله: Asian Journal of Green Chemistry
- نوع مقاله: Journal Article
- کلمات کلیدی: DMF/trichloroisocyanuric acid DMF/trichlorotriazine Green Vilsmeier,Haack reagents Rate enhancements Microwave assisted reactions
- چکیده:
- چکیده انگلیسی: In the present study, we have accomplished N,N’-dimethyl formamide (DMF)/trichloroisocyanuric acid and DMF/trichlorotriazine as efficient catalysts for the synthesis of 3,4-dihydropyrimidinones/thiones from one-pot multi-component reaction of β-ketoester, aromatic aldehydes, and urea under reflux condition. The reaction operates also under solvent free microwave condition. The results obtained from this study were compared with those obtained from classical Vilsmeier-Haack adducts (DMF/POCl3 and DMF/SOCl2) as catalysts. Reaction times and product yields observed in this study indicated shorter reaction times and better product yields with modified VH reagents (TCCA/DMF and TCTA/DMF) over classical VH reagents (POCl3/DMF and SOCl2/DMF). The catalytic activity of (TCTA/DMF)>(TCCA/DMF)>(POCl3/DMF>SOCl2/DMF).
- انتشار مقاله: 18-05-1398
- نویسندگان: Govardhan Duguta,Satish Kumar Mukka,Hemanth Sriram Yelike,Chinna Rajanna Kamatala,Sai Sudhakar Mukka
- مشاهده
- جایگاه : پژوهشی
- مجله: Asian Journal of Green Chemistry
- نوع مقاله: Journal Article
- کلمات کلیدی: Quinolinium chlorochromate,Quinolinium dichromate,NaNO2/KHSO4,Nitration,NH4SCN/KHSO4
- چکیده:
- چکیده انگلیسی: Quinolinium dichromate (QDC) and quinolinium chlorochromate (QCC) were studied as efficient reagents for electrophilic aromatic nitration using sodium nitrite and thiocyanation by using ammonium thiocyanate under conventional, ultrasonic and solvent-free microwave assisted conditions. The microwave-assisted protocols exhibited remarkable rate acceleration and offered selective thiocyanation of the aromatic and heteroaromatic compounds with good yields. Addition of anionic (SDS) micelle to the reaction medium afforded considerable rate enhancements, while cationic (CTAB) and nonionic (Tx-100) micelles did not affect the rate noticeably. These protocols have were extended to regioselective thiocyanation of various aromatic compounds. Results were are completely similar to the nitration protocols. However, the reactions revealed comparatively shorter reaction times, and better yields in nitration reactions than in thiocyanation protocols. Catalytic effect of the SDS was attributed to the electrostatic stabilization of the cationic electrophile (NO2+ in nitration, and SCN+ in thiocyanation).
- انتشار مقاله: 27-07-1396
- نویسندگان: Satish Babu Kodali,Narendar Reddy Jakku,Chinna Rajanna Kamatala,Rajeshwar Rao Yerraguntla,Ivon Chakravarthi Elisha
- مشاهده
- جایگاه : پژوهشی
- مجله: Asian Journal of Green Chemistry
- نوع مقاله: Journal Article
- کلمات کلیدی: Si-supported BrØnsted acids,Green reuasble catalysts,NaHSO3,Sulfonation,aromatic compounds
- چکیده:
- چکیده انگلیسی: A green protocol is described for sulfonation of aromatic compounds that has been accomplished using sodium bisulfite (NaHSO3) in the presence of reusable green heterogeneous SiO2/HClO4 and SiO2/KHSO4 (Silica-supported HClO4 and KHSO4 catalysts) under conventional and solvent-free microwave irradiation. The reactions afforded very good yields of products within 3 to 5 hour under conventional conditions. However, the reaction times in microwave-assisted protocol are drastically reduced to 3 to 5 minutes (from 3 to 5 hour under conventional conditions) followed by increasing product yields. Moreover, the developed silica-supported catalysts could be recycled for at least three to four times.
- انتشار مقاله: 25-05-1396
- نویسندگان: Touheeth Fatima,Yeike Hemanth Sriram,Mukka Satish Kumar,Marri Venkateswarlu,Chinna Rajanna Kamatala
- مشاهده