02093nas a2200229 4500008004100000022001400041245011100055210006900166260000800235300001400243490000700257520131100264653002001575653001701595653001701612653001801629653001701647100002701664700002101691700002101712856013001733 2020 eng d a2585-729000aSelective monoalkylation of hydroquinone in the presence of SO3H-functionalized ionic liquids as catalysts0 aSelective monoalkylation of hydroquinone in the presence of SO3H cDEC a4461-44710 v743 a

A process aiming atO-alkylation of hydroquinone (HQ), where ionic liquids (ILs) act as catalyst is objectively described. Five SO3H-functionalized ILs having different cations were prepared and characterized by NMR and FTIR techniques. The acidity and thermal stability of ILs were determined by Hammett function and thermogravimetric analysis (TGA), respectively. The catalytic activity of these ILs were tested forO-alkylation of HQ with methanol in 4-methoxyphenol (4MP) in the presence of small amount of benzoquinone (BQ). The effect of reaction parameters such as temperature, time, catalyst loading and substrate concentration on the conversion of HQ and product distribution was examined and optimized to maximize the yield of 4MP using 1,3-disulfonic acid imidazolium hydrogen sulfate (IL2) catalyst. Maximum yield of desired product 4MP 93.79% was obtained at 338 K temperature, 5.45 x 10(-2) mol HQ, 8.33 x 10(-3) mol BQ, and 10.37 mol% catalyst loading in 120 min reaction time. Single-product formation was observed up to 338 K temperature but higher temperature (above 338 K) and longer reaction time resulted in the formation of 2,4-dimethoxyphenol (24DMP) as a by-product. Catalyst recyclability was also established up to the fifth run which showed no declination in its activity.

10a4-Methoxyphenol10aBenzoquinone10aHydroquinone10aionic liquids10aO-alkylation1 aBhongale, Priyanka, V.1 aJoshi, Sunil, S.1 aMali, Nilesh, A. uhttps://library.ncl.res.in/content/selective-monoalkylation-hydroquinone-presence-so3h-functionalized-ionic-liquids-catalysts02248nas a2200241 4500008004100000022001400041245011700055210006900172260000800241300001400249490000800263520142700271653002001698653001701718653001801735653002101753653001701774100002301791700002301814700002101837700002101858856012701879 2022 eng d a0008-403400aKinetic study on alkylation of hydroquinone with methanol over SO3H functionalized Bronsted acidic ionic liquids0 aKinetic study on alkylation of hydroquinone with methanol over S cOCT a2986-29960 v1003 a

O-alkylation of a dihydric phenol (i.e., hydroquinone) with methanol in presence of benzoquinone catalyzed by double SO3H functionalized Bronsted acidic ionic liquids (i.e., 1,3-disulphonic acid imidazolium hydrogen sulphate, 1,3-disulphonic acid benzimidazolium hydrogen sulphate, and sulphuric acid) is studied in a batch reactor. The sensitivity of activity and selectivity with reaction time, temperature, speed of agitation, and catalyst loading was examined. The plausible reaction pathways proposed based on the experimental observations and detailed kinetic investigation are performed by assuming a homogeneous reaction phase. The kinetic parameters, such as pre-exponential factor and activation energy, are estimated for both ionic liquids and sulphuric acid by considering all competitive reactions, and comparative results were presented. An extended form of the Arrhenius equation is used to estimate the kinetic parameters for the reaction which showed curvature in lnk against a 1/T plot. The model prediction with the estimated kinetic parameters is in good agreement with the experimental data, which confirmed the model validity in the experimental operating range. It was found that ionic liquid has a potential application in the synthesis of a selective monoalkylated product of hydroquinone. The kinetic analysis performed is found to be useful in the understanding of process behaviour.

10a4-Methoxyphenol10aHydroquinone10aionic liquids10aKinetic analysis10aO-alkylation1 aBhongale, Priyanka1 aAmonkar, Amogh, A.1 aJoshi, Sunil, S.1 aMali, Nilesh, A. uhttps://library.ncl.res.in/content/kinetic-study-alkylation-hydroquinone-methanol-over-so3h-functionalized-bronsted-acidic02458nas a2200229 4500008004100000022001400041245007800055210006900133260000800202300001200210490000700222520175400229653002301983653001702006653001302023653001702036653001102053100002302064700001702087700001702104856010702121 2023 eng d a0161-494000aComprehensive review on catalytic O-alkylation of phenol and hydroquinone0 aComprehensive review on catalytic Oalkylation of phenol and hydr cAPR a455-5000 v653 a

The alkylation process involves two competitive paths of O- and C-alkylation and achieving better selectivity for desired products is a very challenging problem. The development of new process for synthesis of O-methylated products of phenol and dihydric phenols is a subject of high industrial and academic interest. Alkyl phenyl ethers, especially anisole and 4-methoxyphenol, have captivated significant interest due to their increasing applications in pharmaceutical industries. The main emphasis of the present review is to explore the recent development in two catalytic O-alkylation processes. The first process is O-methylation of phenol into anisole and another is selective mono O-methylation of hydroquinone into 4-methoxyphenol. The present article covers O-alkylation methods with methanol and dimethyl carbonate as alkylating agent over various acidic and basic catalytic systems. The catalyst systems analyzed involves Bronsted and Lewis acidic and basic ionic liquids, conventional acids, metal oxides, solid acid and basic catalysts, hydrotalcites, various zeolites and heteropolyacids. The mechanistic behavior of alkylation reactions in presence of different catalytic system is reviewed critically which is important to design new and/or modified catalyst in order to maximize the yield of desired product. Additionally, an influence of reaction parameters, role of catalyst and their active sites on product distribution is described. The review paper gives useful insight for researchers in the field of catalysis and reaction engineering of alkylation reactions. Understandings of the reaction pathways will help in developing reliable kinetic models necessary for process scale-up to industrial scale reactor system.

10aDimethyl carbonate10aHydroquinone10aMethanol10aO-alkylation10aphenol1 aBhongale, Priyanka1 aJoshi, Sunil1 aMali, Nilesh uhttps://library.ncl.res.in/content/comprehensive-review-catalytic-o-alkylation-phenol-and-hydroquinone