18494-86-5Relevant academic research and scientific papers
A New Green and Efficient Br?nsted: Lewis Acidic DES for Pyrrole Synthesis
Shaibuna,Theresa, Letcy V.,Sreekumar
, p. 2359 - 2372 (2018)
Abstract: Deep eutectic solvents (DESs) are fluids composed of different Lewis or Br?nsted acids and bases, generally acknowledged as new analogues to ionic liquids (ILs), because of their similar characteristics, but with more advantages related to preparation cost, environmental impact etc. Their preparation involve the simple mixing of two components generally with moderate heating that are inexpensive, non-toxic, biodegradable and the resulting mixture is capable to overcome the drawbacks of conventional organic solvents and ILs. Chemical reactions with these materials are significantly less hazardous and they can act as catalysts as well as reaction media. Here, three new DESs based on ZrOCl2·8H2O in combination with urea, ethylene glycol and glycerol are introduced. Physicochemical properties like phase behaviour, Freezing point, density, viscosity, thermal stability and miscibility properties in common solvents are determined. In addition, a new method for the determination of acidity of DESs having both Br?nsted and Lewis sites is also introduced in this work. A convenient synthesis of pyrrole through Paal–Knorr reaction is reported using a variety of amines which are used to establish the importance of this catalyst in organic reactions. The products are analysed by GC–MS, 1H NMR and 13C NMR. By comparing the three DESs, DES 1 (formed from ZrOCl2·8H2O with urea) has the lowest density, viscosity, highest acidity and thermal stability. It was shown to be an excellent green catalyst for Paal–Knorr reaction. Reusability of the catalyst was also achieved up to 4 runs, without significant loss in its catalytic activity. Graphical Abstract: [Figure not available: see fulltext.]
Grinding solvent-free paal-knorr pyrrole synthesis on smectites as recyclable and green catalysts
Marvi, Omid,Nahzomi, Hossein Taherpour
, p. 139 - 147 (2018)
An environmentally benign method for the synthesis of N-substituted pyrroles from one-pot solvent-free condensation reaction of 2,5-hexanedione with various primary amines (Paal-Knorr pyrrole synthesis) on smectite clays as green and reusable heterogeneous Lewis acid catalysts is presented. The use of nontoxic, inexpensive, easily available and reusable catalysts under solvent-free conditions make this protocol practical, environmentally friendly and economically attractive.
Xanthan sulfuric acid as an efficient, green, biodegradable, and recyclable solid acid catalyst for one-pot synthesis of N-substituted pyrroles under solvent-free conditions at room temperature
Rahmatpour, Ali
, p. 491 - 495 (2012)
A new, green, and efficient method for synthesis of a variety of N-substituted pyrroles from condensation reactions of 2,5-hexanedione with amines or diamines using xanthan sulfuric acid as a biosupported and reusable ecofriendly catalyst under solvent-free conditions at room temperature is described. The use of a nontoxic, inexpensive, easily available, and reusable biosupported proton source catalyst under solvent-free conditions makes this protocol practical, environmentally friendly, and economically attractive.
Cobalt(ll) chloride as a novel and efficient catalyst for the synthesis of 1,2,5-trisubstituted pyrroles under solvent-free conditions
De, Surya K.
, p. 592 - 595 (2008)
CoCl2 is used as an efficient catalyst in the Paal-Knorr condensation of 2,5-hexadione with primary amines under solvent-free conditions, leading to the formation of pyrrole derivatives in excellent yield. This method is very easy, rapid, and high yielding reaction for the synthesis N-substituted pyrrole derivatives.
A simple synthesis of pyrroles catalyzed by acidic resin under solvent-free condition
Yuan, Shizhen,Li, Zhen,Xu, Ling
, p. 446 - 448 (2010)
A simple and effective Paal-Knorr condensation of 2, 5-hexanedione with most amines has been carried out at room temperature under solvent-free condition. The pyrroles were obtained in high yields and in short reaction times.
Montmorillonite KSF-mediated facile synthesis of pyrroles
Samajdar, Susanta,Becker, Frederick B.,Banik, Bimal K.
, p. 1019 - 1022 (2001)
A facile synthesis of substituted pyrroles over montmorrilonite KSF clay has been accomplished in excellent yield.
Simple synthesis of pyrroles under solvent-free conditions
De, Surya K.
, p. 2768 - 2774 (2008)
Paal-Knorr condensation of 2,5-hexadione with primary amines in the presence of a catalytic amount of praseodymium(III) trifluoromethanesulfonate under solvent-free conditions has been accomplished with an excellent yield. This method is a very easy, rapid, and high-yielding reaction for the synthesis of N-substituted pyrrole derivatives. Copyright Taylor & Francis Group, LLC.
Sulfamic acid as a novel, efficient, cost-effective, and reusable solid acid catalyst for the synthesis of pyrroles under solvent-free conditions
De, Surya K.
, p. 803 - 809 (2008)
Paal-Knorr condensation of 2,5-hexadione with primary amines in the presence of a catalytic amount of sulfamic acid under solvent-free conditions has been accomplished with an excellent yield. This is a very easy, rapid, and high-yielding reaction for the synthesis N-substituted pyrrole derivatives. Copyright Taylor & Francis Group, LLC.
A convenient synthesis of pyrroles catalyzed by acidic resin under solvent-free condition
Yuan, Shi Zhen,Liu, Jin,Xu, Ling
, p. 664 - 668 (2010)
A convenient and effective Paal-Knorr condensations of 2,5-hexanedione with most amines have been carried out at room temperature under solvent-free condition. Macroporous strongly acidic styrol resin (D001) as a novel, efficient, cost-effective, and reusable solid acid catalyst for the synthesis of pyrroles under the same conditions. The pyrroles were obtained in high yields in short reaction times.
1-Methylimidazolium hydrogen sulfate catalyzed convenient synthesis of 2,5-dimethyl-N-substituted pyrroles under ultrasonic irradiation
Li, Daqing,Zang, Hongjun,Wu, Changchun,Yu, Nianqin
, p. 1144 - 1148 (2013)
Ionic liquid [HMIM]HSO4 was found to be an efficient catalyst for the synthesis of N-substituted pyrroles through the reaction of 2,5-hexanedione with amines under ultrasonic irradiation at room temperature. These reactions proceed with good yields under short reaction time. Furthermore, the green catalytic system can be recycled specific times with no decreases in yields and reaction rates.
