14617-92-6Relevant articles and documents
Aerobic oxidative esterification and thioesterification of aldehydes using dibromoisocyanuric acid under mild conditions: No metal catalysts required
Kwon, Young-Do,La, Minh Thanh,Kim, Hee-Kwon
, p. 10833 - 10841 (2018/07/05)
A practical direct method for the direct preparation of esters and thioesters from aldehydes is described. Esters and thioesters were synthesized by oxidative esterification and thioesterification via in situ generated acyl bromide intermediates, which were used to react with various alcohols and thiols. The esterification and thioesterification were readily performed in the presence of dibromoisocyanuric acid in dichloromethane, without any metal catalysts and under mild conditions. By using this reaction protocol, various esters and thioesters were prepared in high yields. This effective method offers a promising approach for the facile esterification and thioesterification of aldehydes.
The insertion of arynes into the O-H bond of aliphatic carboxylic acids
Wen, Chunxiao,Chen, Qian,He, Zhenwen,Yan, Xinxing,Zhang, Changyuan,Du, Zhiyun,Zhang, Kun
supporting information, p. 5470 - 5473 (2015/09/15)
The insertion of arynes into the O-H bond of aliphatic carboxylic acids promoted by sodium carboxylates is described. The reactions led to the formation of aryl carboxylates in good yields with good chemoselectivities under mild conditions.
Active and deactive modes of modified montmorillonite in p-cresol acylation
Venkatesha,Chandrashekara,Jai Prakash,Bhat
, p. 181 - 187 (2014/06/24)
para-Toluene sulphonic acid (p-TSA)-treated montmorillonite clay used as heterogeneous catalyst in acylation of para-cresol (PC) with aliphatic carboxylic acids. Reactions were studied under microwave and conventional modes of heating and reaction conditions were optimized by varying mole ratio, temperature, amount of catalyst and reaction time. Under optimized conditions the reaction was carried out involving p-cresol and decanoic acid. The reaction involved two steps, O-acylation involving ester formation followed by the Fries rearrangement involving C-acylation resulting in ketone product. Microwave heating mode showed higher conversion and the catalytic activity almost retained in repeated use. On the other hand the catalytic activity dropped by more than 50% in the case of conventional heating indicating rapid deactivation. A change in the color of the used catalyst was more intense in the case of conventional than in the microwave heating. Used catalysts were characterized for surface area and pore volume by BET technique, acidity by FTIR spectroscopy and amount of coke by TGA. Further investigations on the catalyst used in conventional heating revealed that the deactivation occurred during the O-acylation and not in the subsequent Fries rearrangement. However, the catalyst in the microwave irradiated reaction, exhibited a retarded rate of formation of coke precursors on the surface during O-acylation, thus preventing any decrease in catalytic activity. Present study indicates that the technique chosen for heating the reaction medium plays an important role in suppressing deactivation.
Efficient and catalyst-free condensation of acid chlorides and alcohols using continuous flow
Van Waes, Frederik E. A.,Cukalovic, A.,Stevens, Christian V.,Drabowicz, J.
, p. 2776 - 2779,4 (2020/09/14)
An efficient, catalyst-free continuous flow procedure for the condensation of acid chlorides and alcohols was developed. Different esters could be obtained using this protocol with excellent conversions starting from the corresponding acid chlorides and alcohols in very short reaction times (5-7 min). The reaction was performed solventless for liquid reagents but requires a solvent for solid reagents in order to prevent clogging of the microreactor. Since no catalyst is needed, the purification of the reaction mixture is very straightforward. Scale-up of the reaction to a microreactor with an internal volume of 13.8 ml makes it possible to produce 2.2 g min-1 of ester with an isolated yield of 98% and recuperation of the formed HCl.
Microwave-induced deactivation-free catalytic activity of BEA zeolite in acylation reactions
Chandra Shekara,Jai Prakash,Bhat
scheme or table, p. 101 - 107 (2012/07/14)
Solventless liquid-phase acylation of p-cresol with different aliphatic carboxylic acids like acetic, propionic, butyric, hexanoic, octanoic, and decanoic acids was investigated over BEA zeolite under conventional as well as microwave heating. An unanticipated huge difference in activity was observed between two modes of heating. Under conventional heating, conversion of all the acids was less than 20%, while under microwave heating, the conversion was in the range of 50-80%. Ester formed through O-acylation and ortho-hydroxyketone formed through Fries rearrangement of the ester were the only products. Conversion of carboxylic acid increased with chain length up to hexanoic acid and then it showed a decrease in the trend. With all the acids, O-acylation occurred rapidly followed by slow conversion to ortho-hydroxyketone. The ketone/ester ratio increased with catalyst amount, temperature, and reaction time. Used catalyst samples were characterized by TGA, XRD, and IR studies to understand lower activity and deactivation behavior under conventional heating. The results showed absence of coke precursor/coke on the catalyst used in microwave-irradiated reactions in contrast to catalyst used in conventionally heated ones. Higher yield in the case of microwave-assisted reactions is attributed to the prevention of coke precursor/coke on the active sites by microwaves.
Ytterbium triflate catalysed Friedel-Crafts reaction using carboxylic acids as acylating reagents under solvent-free conditions
Jin, Can,Li, Jie,Su, Weike
experimental part, p. 607 - 611 (2011/02/26)
The Friedel-Crafts acylation of 1-naphthol and phenol derivatives with carboxylic acids were investigated by using a catalytic amount of metal-triflate, in particular Yb(OTf)3, under solvent-free conditions. Both aliphatic and aromatic carboxylic acids reacted easily to afford the corresponding hydroxyaryl ketones.
Direct esterification of carboxylic acids with p-cresol catalysed by acid activated Indian bentonite
Vijayakumar,Iyengar, Pushpa,Nagendrappa, Gopalpur,Prakash, B.S. Jai
, p. 1950 - 1953 (2007/10/03)
Acid activated Indian bentonite (AAIB) catalyst is used for the first time to esterify various carboxylic acids with p-cresol in average to excellent yields. Optimisation studies have been carried out for p-cresyl stearate synthesis. The catalyst is recoverable and recyclable.
Lipase catalyzed esterification of cresols
Suresh Babu,Karanth,Divakar
, p. 1068 - 1071 (2007/10/03)
Esters of m- and p-cresols with organic acids having carbon chain lengths C2-C18 have been prepared by using lipases from porcine pancreas and Rhizomucor miehei. Gram level conversions are carried out under non-solvent conditions in case of shake flask experiments and continuous removal of water at bench-scale levels. Addition of 0.1 mL of 0.1M phosphate buffer at pH 7.0 to the reaction mixture shows better conversions. Optimization studies have been carried out for p-cresyl laurate synthesis using Rhizomucor miehei lipase which show a maximum conversion of 74.4 %. Better conversions are obtained with larger amounts of enzyme. Porcine pancreas lipase catalyzed synthesis of m- and p-cresyl esters show that under identical reaction conditions acids with lower carbon chain lengths (C2-C4) give ester yields above 30%, while those with longer carbon chain lengths give ester yields 30%.