Liquid–liquid–solid mass transfer and phase behavior of heterogeneous etherification of glycerol with isobutene

Previous experiments observed auto‐acceleration in the etherification of glycerol with isobutene. This article engaged to uncover the reason for this phenomenon via investigating the heterogenicity, including liquid–liquid phase equilibrium and liquid–liquid–solid mass transfer, of the reaction system. Phase behavior analysis showed that the reaction mixture separates into two liquid phases during the whole course of the reaction. The produced mono ethers of glycerol thermodynamically promote the homogenization of the two liquid phases. The modeling results of liquid–liquid–solid mass transfer indicated that the resistance of mass transfer is insignificant during the reaction. The bulk compositions of the two liquid phases are very close to their corresponding equilibrium compositions. An increase of isobutene concentration in the reaction phase is believed to lead all reactions speeding up. © 2018 American Institute of Chemical Engineers AIChE J, 64: 2526–2535, 2018     

Formation of Di-isobutene,main by-product of methyl tertiary butyl ethyl ether synthesis catalyzed by ion exchange resin

An experimental set-up is presented for the measurement of steady-state reaction rates in the liquid phase methyl tertiary butyl ether (MTBE) synthesis from isobutene and methanol using ion exchange resin as catalyst. This apparatus was used for a separate investigation of the main side reaction, i.e., the formation of isobutene dimers (DIB), in the temperature range between 60 and 90°C. The reaction catalyzed by Amberlyst 15 (A15) showed no steady-state behaviour, but the catalytic activity declined at a rate dependent on the reaction conditions. Time constants for activity loss were determined in the range from 3.5 to 30 h. The deactivated A15 catalyst could be regenerated through MTBE synthesis experiment. Deactivation is assumed to be caused by blocking of the microparticle gel phase by higher isobutene oligomers. The DIB formation, using 1-butene as solvent, was of 2nd order with respect to isobutene and showed an apparent activation energy of about 40 kJ/mol.     

Gas phase hydration of isobutene to tert-butyl alcohol on H4SiW12O40 as the catalyst

Catalytic hydration of isobutene in gas phase on solid dodecatungstophosphoric acid has been studied at 313–353 K in a constant flow microreactor. Besides the main product tert-butyl alcohol (TBA) the isobutene dimer was detected in the gas phase the concentration of which increased with the space time and decreased with temperature. Selectivity to TBA was 40–80% depending on the conditions. The rate of isobutene conversion reached maximum at 328 K. Separate sorption experiments have shown that water vapour is rapidly sorbed by the whole volume of the catalyst while there is no such sorption of isobutene, which is adsorbed only on the surface. Based on these results qualitative model of the reaction pattern was proposed including the formation of carbenium ions on the surface. Subsequently they would react with water molecules supplied from the bulk of the catalyst. The latter is also the source of protons bonded by isobutene molecules.     

A New One‐Pot Synthesis of Polysubstituted Indoles from Pyrroles and β‐Nitroacrylates

The reaction of β‐nitroacrylates with pyrroles, under solvent‐ and catalyst‐free conditions, allows the formation of Friedel–Crafts adducts which, after in situ treatment with Amberlyst 15 in isopropyl alcohol under reflux, provide polysubstituted indoles, via a benzannulation reaction, in a one‐pot process.     

Methyl tert-butyl ether decomposition over heteropoly acid catalyst in a cellulose acetate membrane reactor

In this study the methyl tert-butyl ether (MTBE) decomposition over H₃PW₁₂O₄₀ was carried out in a cellulose acetate membrane reactor. The permeability of methanol through the cellulose acetate membrane was about 30 and 300 times higher than that of either isobutene or MTBE, respectively. The isobutene selectivity in the fixed bed reactor was only slightly higher than the methanol selectivity due to the side reaction. In the cellulose acetate membrane reactor, however, the isobutene selectivity in the rejected stream was 68% and the methanol selectivity in the permeated stream was up to 97%. The MTBE conversion in the membrane reactor was about 7% higher than that in the membrane-free fixed bed reactor under the same reaction conditions. The enhanced performance of the membrane reactor in this reversible reaction was mainly due to the selective permeation of methanol which resulted in a methanol-deficient condition suppressing MTBE synthesis reaction.     

Reactivity,chemical structure,and molecular mobility of urea–formaldehyde adhesives synthesized under different conditions using FTIR and solid‐state 13C CP/MAS NMR spectroscopy

This study was conducted to investigate the effects of reaction pH condition and hardener type on the reactivity, chemical structure, and molecular mobility of urea–formaldehyde (UF) resins. Three different reaction pH conditions, such as alkaline (7.5), weak acid (4.5), and strong acid (1.0), were used to synthesize UF resins, which were cured by adding four different hardeners (ammonium chloride, ammonium sulfate, ammonium citrate, and zinc nitrate) to measure gel time as the reactivity. FTIR and ¹³C‐NMR spectroscopies were used to study the chemical structure of the resin prepared under three different reaction pH conditions. The gel time of UF resins decreased with an increase in the amount of ammonium chloride, ammonium sulfate, and ammonium citrate added in the resins, whereas the gel time increased when zinc nitrate was added. Both FTIR and ¹³C‐NMR spectroscopies showed that the strong reaction pH condition produced uronic structures in UF resin, whereas both alkaline and weak‐acid conditions produced quite similar chemical species in the resins. The proton rotating‐frame spin–lattice relaxation time (T_1ρH) decreased with a decrease in the reaction pH of UF resin. This result indicates that the molecular mobility of UF resin increases with a decrease in the reaction pH used during its synthesis. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2677–2687, 2003     

Chiral Thiourea‐Phosphine Organocatalysts in the Asymmetric Aza‐Morita–Baylis–Hillman Reaction

A new kind of bifunctional (thio)urea‐phosphine catalyst was synthesized and applied to the aza‐Morita–Baylis–Hillman reaction of N‐sulfonated imines with methyl vinyl ketone, phenyl vinyl ketone, ethyl vinyl ketone or acrolein. Moderate to excellent ee and yields of the products were obtained under mild reaction conditions.     

Robust Optimal Design of an Glycerol Etherification Process

Glycerol ethers are valuable fuel additives produced by reaction of glycerol with isobutene. The processes presented in the literature use high‐purity isobutene and are designed assuming accurate knowledge of reaction kinetics and physical properties. The optimal design of a plant processing 2.25 kmol h^–1 glycerol, using isobutene of 90 % purity, is addressed considering the uncertainty of the design data. Plants with small reactors have the lowest total annual cost, but the recycle flow rates greatly increase when uncertain variables affect the process, constraining the operation feasibility. The optimal design, fulfilling the constraints despite uncertainty, is found by constructive nonlinear dynamics. The robustness of the optimal design is proved by dynamic simulation.     

Postcrosslinking of macroporous styrene–divinylbenzene copolymers via pendant vinyl groups: Effect of the starting copolymers on the pore structure of the postcrosslinked products

In the presence of anhydrous ferric chloride as a Friedel–Crafts catalyst, the postcrosslinking reaction of macroporous styrene–divinylbenzene (St–DVB) copolymers synthesized under different conditions was carried out with 1,2‐dichloroethane as a solvent. Without an externally added crosslinking agent, the specific surface area and pore volume, for copolymers with different DVB isomers or different DVB contents after reaction, in most cases increased significantly, and the increase was found to be heavily dependent upon the amount of the pendant vinyl groups in the starting copolymers. These results further confirm the role of the pendant vinyl groups in creating new crosslinking bonds in addition to those created by a free‐radical crosslinking reaction in the starting copolymers, and an alkylation reaction of the vinyl groups with neighboring aromatic rings is believed to dominate the course of the postcrosslinking at a relatively high level of the vinyl group contents. The synthesis conditions, including the n‐heptane content in a mixed diluent and the amount of the diluent, under which the starting copolymers were synthesized, play an important role in the increase of the surface area and pore volume of the copolymers after postcrosslinking. The effect of these conditions is attributed mainly to the swelling ability of the starting copolymers thus obtained in the solvent used for reaction. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1668–1677, 2002     

Effect of glass transition temperature on heat‐responsive gas bubbles formation from polymers containing tert‐butoxycarbonyl moiety

Various types of polymers containing tert‐butoxycarbonyl (BOC) moiety as the typical protecting group of functional moieties have been used for the design of stimuli‐responsive polymer materials. In this study, we investigated the heat‐responsive deprotection behavior of BOC‐containing polymers obtained by radical polymerization of 4‐(tert‐butoxycarbonyloxy)styrene (BSt) and copolymerizations of BSt with styrene and methyl acrylate. The deprotection of BOC groups accompanying the evolution of isobutene and carbon dioxide as gaseous products was monitored by thermogravimetric analyses at different temperature circumstances; that is, on heating at a rate of 10 °C/min and under isothermal conditions at various temperatures. The deprotection resulted in a significant decrease in the transmittance of visible light due to the formation of a large number of gas bubbles, that is, foaming, in the polymer films when a heating temperature was close to the glass transition temperature of the used polymer. The potential of BOC‐containing polymers was also evaluated as the heat‐responsive adhesive polymers for dismantlable adhesion. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46252.     

Gold‐Catalyzed Intermolecular Reactions of (Z)‐Enynols with Indoles for the Construction of Dihydrocyclohepta[b]indole Skeletons through a Cascade Friedel–Crafts/Hydroarylation Sequence

An efficient domino approach for the synthesis of indole‐fused carbocycles and their analogues from the reactions of suitably substituted (Z)‐enynols with indoles or pyrroles under mild reaction conditions was developed. This methodology is realized by a tandem reaction using Au/Ag catalysts, which could catalyze both of the Friedel–Crafts and the hydroarylation reaction in the same vessel.     

N‐Methylprolinol Catalysed Asymmetric Baylis−Hillman Reaction

N‐methylprolinol is used as a chiral base catalyst for the Baylis–Hillman reaction to obtain the adducts in good yields with moderate to good enantioselectivities in 1,4‐dioxane:water (1 : 1, v/v) under ambient conditions.     

阳离子交换树脂催化合成乙基叔丁基醚

采用卤化和磺化处理制备了阳离子交换树脂LH,并将其用于乙醇与异丁烯催化醚化合成乙基叔丁基醚。利用单因素实验考察醇烯物质的量比、反应温度、空速和反应压力对催化剂性能的影响。结果表明,在醇烯物质的量比1.198、反应温度65℃、空速3 h-1和反应压力1.50 MPa条件下,乙基叔丁基醚收率达85.5%。     

Optimisation study of large‐scale enzymatic synthesis of oleyl oleate,a liquid wax ester,by response surface methodology

An optimisation study of the large‐scale enzymatic synthesis of a liquid wax ester from oleic acid and oleyl alcohol using Novozym 435 was carried out. Investigations were performed in batch mode with a stirred tank reactor (STR) with one multi‐bladed impeller. Response surface methodology (RSM) based on a five‐level, three‐variable central composite rotatable design (CCRD) was used to evaluate the interactive effects of various parameters. The parameters are amount of enzyme (A) (90–120 g), impeller speed (B) (100–400 rpm) and temperature (C) (40–60 °C). The optimum conditions derived via RSM at a fixed reaction time of 1 h were successfully optimised as A = 104 g, B = 388.0 rpm and C = 49.7 °C. The actual experimental yield was 96.7% under the optimum conditions, which compared well with the maximum predicted value of 97.6%. Copyright © 2005 Society of Chemical Industry     

Homogeneous synthesis and characterization of polyacrylamide‐grafted cationic cellulose flocculants

In this work, cationic cellulose (CC) with different degrees of substitution (DS) was successfully synthesized by the reaction between cellulose and 3‐chloro‐2‐hydroxypropyl‐trimethylammonium chloride (CHPTAC) in a 7 wt % NaOH and 12 wt % urea aqueous solution. The structure of the CC was characterized by using elemental analysis, ¹H‐NMR, and FTIR. The DS values of CC ranged between 0.18 and 0.50, which could be obtained by adjusting the reaction temperature, reaction time, and molar ratio of CHPTAC to anhydroglucose unit of cellulose. The cationic cellulose–graft–polyacrylamide flocculant (CC‐g‐PAM) based on CC and polyacrylamide (PAM) was also synthesized in a homogeneous aqueous solution. The flocculation characteristics of CC and CC‐g‐PAM were evaluated in a kaolin suspension. The results showed that CC‐g‐PAM was an effective flocculant for the kaolin suspension under acidic or neutral conditions, and the flocculation efficiency was over 90%, while the CC showed better flocculation performance under alkaline conditions. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43106.     

Asymmetric Carbon‐Carbon Bond Forming Reactions Catalysed by Metal(II) Bis(oxazoline) Complexes Immobilized using Supported Ionic Liquids

A series of bis(oxazoline) metal(II) complexes has been supported on silica and carbon supports by non‐covalent immobilisation using an ionic liquid. The catalytic performance of these solids was compared for the enantioselective Diels–Alder reaction between N‐acryloyloxazolidinone and cyclopentadiene and the Mukaiyama‐aldol reaction between methyl pyruvate and 1‐methoxy‐1‐trimethylsilyloxypropene. In both reactions the enantioselectivity was strongly influenced by the choice of support displaying enantioselectivies (ee values) up to 40% higher than those conducted under homogeneous reaction conditions.     

环境友好型叔丁胺制备工艺技术

研究以HZP-II催化剂、异丁烯和液氨为原料,选择了直接胺化制备叔丁胺的工艺路线,考察了空速、氨烯比、压力、温度对反应转化率的影响,并对催化剂使用寿命进行了稳定性评价。实验结果表明,在反应压力5 MPa、反应温度260 ℃、异丁烯空速450 h―1、氨烯比（1.5～3.0）∶1时,反应2000 h以上,异丁烯单程转化率仍能保持10.2%,产物叔丁胺的选择性>99%。     

Herstellung von Glycerin‐tert‐butylethern – Entwicklung vom Labor bis zur Miniplant

Di‐ and tri‐tert‐butyl ethers of glycerol (h‐GTBE) are magnificently miscible with numerous hydrocarbons due to their nonpolar properties. They have excellent combustion characteristics, what makes them especially attractive as additives in fuels. This work deals with the acid‐catalyzed hydroalkoxylation of glycerol and isobutene for the production of h‐GTBE. Preliminary investigations enabled the determination of the reaction parameters and separation of the products. With recovery of the substrates, a continuously operated miniplant was established in a long‐term performance.     

Synthesis of 1-tert-butoxy-2-propanol (PGTBE) from propylene glycol and isobutene in a packed trickle-bed reactor on acid catalysts

1-tert-Butoxy-2-propanol has been synthesized from propylene glycol and isobutene over two solid acid catalysts, montmorillonite and Amberlyst 15, in a packed trickle-bed reactor operating under different experimental conditions, and its antiknock properties as an oxygenate gasoline additive have been evaluated. The reaction on Amberlyst 15 fitted first-order kinetics for isobutene (k′=0.37 h⁻¹) for a molar ratio propylene glycol to isobutene of one.     

Response surface methodology as a tool to study the lipase‐catalyzed synthesis of betulinic acid ester

BACKGROUND: The synthesis of betulinic acid ester using betulinic acid and oleyl alcohol catalyzed by Novozym 435 (immobilized Candida antarctica lipase) was carried out. Response surface methodology (RSM) based on a five‐level, three‐variable, central composite rotatable design (CCRD) was employed to evaluate the interactive effects of various parameters. The parameters were reaction time (8–16 h), temperature (20–60 °C) and enzyme amount (120–160 mg). RESULTS: Simultaneously increasing reaction time, temperature and amount of enzyme increased the yields of betulinic acid ester produced. CONCLUSION: The optimum conditions derived via RSM for the reaction were reaction time of 10.2 h, temperature of 53.1 °C and enzyme amount of 138 mg. The actual experimental yield was 48.5% under optimum conditions, which compared well with the maximum predicted value of 47.6%. Copyright © 2008 Society of Chemical Industry