Batch-wise preparation

The esterification reactor is usually not emptied completely after a batch is finished and a small amount of prepolymer is retained in the reactor. The reason for this is the solubility of TPA in EG and BHET, as discussed earlier in Section 3.1. During operation, the batch-wise prepared slurry is fed continuously into the esterification reactor while the esterification is already proceeding. For a significant part of the process time, the batch esterification reactor is operating semi-continuously. 

In cases where metals or metal ions can contaminate the products, reaction vessels fabricated from inert polymeric materials restrict that possibility. A significant example involved the reaction of maltol with aqueous methylamine to give l,2-dimethyl-3-hydroxypyrid-4-one. The product is a metal chelator employed for the oral treatment of iron overload. Consequently, it is an excellent metal scavenger but must be produced under stringent conditions that preclude metal complexation. Literature conditions involved heating maltol in aqueous methylamine at reflux for 6 h, the product was obtained in 50% yield, but required decolourisation with charcoal135. With the CMR, the optimal reaction time was 1.3 min, and the effluent was immediately diluted with acetone and the near colourless product crystallised from this solvent in 65% yield (Scheme 9.18). A microwave-based batch-wise preparation of 3-hydroxy-2-methylpyrid-4-one from maltol and aqueous ammonia was also developed. 

Because hydrolytic reactions are reversible, they are seldom carried out in batch wise processes [26,28,36,70]. The reactor is usually a double jacket cylindrical flask fitted with a reflux condenser, magnetic stirrer, and thermometer connected with an ultrathermostat. The catalyst is added to the reaction mixture when the desired temperature has been reached [71,72]. A nitrogen atmosphere is used when the reactants are sensitive to atmospheric oxygen [36]. Dynamic methods require more complicated, but they have been widely used in preparative work as well as in kinetic studies of hydrolysis [72-74]. The reaction usually consists of a column packed with a layer of the resin and carrying a continuous flow of the reaction mixture. The equilibrium can... 

The rhodium complexes were prepared in situ from the rhodium precursor [Rh(nbd)2](C104) (nbd = 2,5-norbornadiene) and applied in the hydrogenation experiments under an initial hydrogen pressure of 5 bar at 35°C. The dendrimer structure had almost no effect on the activity of the catalyst in the batch-wise rhodium-catalyzed hydrogenation of dimethyl itaconate (Scheme 4). 

A flavouring essence is a traditional flavouring product prepared by washing a selected oil blend (predominately citrus oils) with an aqueous alcoholic solvent mixture (e.g. 60% ethanol/40% water). It is an extraction process in which the aqueous extract phase becomes the flavouring. The process is earned out under cool temperatures, for example, 5-10°C, either batch-wise or by counter-current extraction. The soluble oxygenated flavouring constituents present in the essential oil blend (e.g. citral in lemon oil) are effectively partitioned between the two phases of the mixture. The low temperatures employed ensure that the transfer of any oil into the hydro-alcoholic phase is minimised as a poorly processed essence will tend to cloud when used in the drink formulation. 

Saka and Kusdiana (2001) at the University of Kyoto investigated methyl-esterification in supercritical methanol without using any catalyst. The experiment was carried out in a batch-wise reaction vessel preheated at 350 and 400 °C at a pressure of 45-65 MPa. In a preheating temperature of 350 °C, 240 s of supercritical treatment with methanol was sufficient to convert the rapeseed oil to FAME, and, although the prepared FAME was basically the same as those of common method with an alkaline catalyst, the yield of FAME obtained at 350 °C was found to be higher than that obtained at 400 °C. The supercritical methanol process required a shorter reaction time and a simpler purification procedure. In addition, by using the supercritical methanol method, FAME was produced not only from triglycerides but also from free fatty acids. 

In the separation processes mentioned so far the introduction of the feed mixture is realised in a batch wise manner on one single column only. Especially for separations in a preparative scale, modes for continuous operation have to be considered to increase productivity, product concentration and to save fresh eluent. 

Pressure resistance of polymer films prepared under various reaction conditions were examined by using a batch-wise reverse osmosis apparatus. Hydrostatic pressure was applied by using a mixture of toluene/methanol as a pressure medium. 

Cross-linked crystals of lipase from Candida rugosa (CRL) were applied in the resolution of racemic ketoprofen chloroethyl ester. In batch-wise operation, the half-life of the catalyst was reached after about 18 cycles or, in terms of enzyme consumption, about 5.6 g of enzyme protein were consumed to prepare 1 kg of (S)-ketoprofen. CRL suffers from a low specific activity towards this poorly water-soluble substrate which may explain the high enzyme input [117]. 

The original procedures for catalyst preparation and use have proven sufficient for large-scale production of many building block targets, but improvements were necessary to enhance the industrial and economic practicality of batch-wise production utilizing this technology. Active catalyst preparation was a general problem because it remained coupled to the resolution reaction, due to the inability to physically isolate the catalyst by means other than concentration to dryness. More specifically, the HKR of epichlorohydrin was additionally handicapped by the presence of a racemization pathway with concomitant side-product formation (see Sec-... 

Polymerization. Copolymers of tetrafluoroethylene/perfluoro(methyl vinyl ether) and the nitrile (1-4 mole ) have been prepared batch-wise in a stirred autoclave using an aqueous ammonium persulfate or ammonium persulfate-sodium sulfite redox couple system at 40°-100° C. The TFE/PMVE gas mixture was pressured, as required, to maintain the pressure and the nitrile pumped in solution in trichlorotrifluoro-ethane. After completion of the reaction, polymer was isolated from the latex (25-30 solids) by coagulation using ethanol and aqueous magnesium chloride solution. It was washed with alcohol/water solutions and dried at 70 °C in an oven under nitrogen. Mass balance indicated that most of the nitrile had been incorporated. 

A large number of microfluidically automated components for batch-wise nucleic acid diagnostics based on pressure driven laminar flow chips have been published and summed up in several reviews [33, 114, 115]. However, a totally integrated system remains a challenge, since the integration of sample preparation proved difficult [115], although it seems to be in reach, as the next two examples show. 

The prepared catalysts were investigated for the hydroformylation of 1-hexene to produce heptanal in a batch-wise, liquid phase reaction (Table 5.6-3), and all results obtained were compared to the identical reaction in the liquid-liquid biphasic process design. 

Glucuronides have been synthesized batch-wise or in a hollow fiber system using microsomal or soluble enzyme preparations (5-5). Furthermore, they have been prepared with enzymes immobilized to polymeric supports (6). Here we describe the continuous synthesis of glucuronide conjugates in a 10-mL membrane reactor (7). 

A survey of recent literature on zeolite-membrane preparation reveals that synthesis processes, even for well-known zeolite structures (i.e., MFI, LTA), are still carried out batch wise, using a hydrothermal route to produce a thin layer from hydrogels or sols containing the corresponding nutrients. 

After the Second World War, penicillin was prepared batch-wise in flat glass bottles, which were stacked up in large racks. 

As the drying process of electric insulators is performed batch wise, the process presents as particularity the lack of steady states. According to this behaviour, the training procedure of the NN has been achieved on the basis of a special prepared set of training data. The training set of data has been chosen in accordance to the industrial control practice. 

Suspension polymerization of methyl methacrylate is used mainly for the production of injection moulding and extrusion grades of polymer. Suspension polymer is also used in the preparation of polymer-monomer doughs for dentures. Polymerization is carried out batch-wise in a stirred reactor, jacketed for heating and cooling the reactor is capable of withstanding a pressure of 3—4 atmospheres. A typical basic formulation might be as follows ... 

Linear unsaturated polyesters are prepared batch-wise by heating a mixture of the appropriate acidic and hydroxy components in a reactor jacketed for heating and cooling and fitted for distillation. A typical formulation for a general-purpose material might be as follows ... 

Typically, reaction is carried out batch-wise in a stirred reactor, jacketed for heating and cooling. The reactor is also fitted with a condenser such that either reflux or distillation may take place, as required. A mixture of phenol, formalin and ammonia (about 1-3% on the weight of phenol) is heated under reflux at about 100°C for 0.25-1 hour and then water is removed by distillation under reduced pressure (to limit further reaction). Distillation is continued until a cooled sample of the residual resin has a melting point in the range 45—50°C. The resin is then quickly discharged and cooled to give a hard, brittle solid. In an alternative procedure, the removal of water is not taken to completion but is halted when the resol content of the residual aqueous solution reaches about 70%. The solution is then used directly, mainly in the preparation of paper laminates. In the preparation of such aqueous solutions, the preferred catalyst is... 

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