Reaction mass concentration

Operating pressure, temperature, composition of the reaction mass (concentration of various components), viscosity, density, any heat evolved during the reaction... 

Operating pressure, temperature, composition of the reaction mass (concentration of various chemicals), viscosity, density, heat evolved during reaction Heating, cooling and washing time cycles during every batch Tendency of the reaction mass to solidify in case of power failure or interruption in heating fluid supply to jacket... 

Erosive properties of the reaction mass Concentration of suspended solids, high relative velocity between lining material and the reactants should be considered as the lining can get peeled off during operation exposing the unlined surface... 

Water-soluble initiator is added to the reaction mass, and radicals are generated which enter the micelles. Polymerization starts in the micelle, making it a growing polymer particle. As monomer within the particle converts to polymer, it is replenished by diffusion from the monomer droplets. The concentration of monomer in the particle remains as high as 5—7 molar. The growing polymer particles require more surfactant to remain stable, getting this from the uninitiated micelles. Stage I is complete once the micelles have disappeared, usually at or before 10% monomer conversion. 

When the batch is completed, a slight excess of oleum and chlorine is added to reduce to a minimum the residual SCI2. Because thionyl chloride combines readily with sulfur trioxide to form the relatively stable pyrosulfuryl chloride, it is necessary to maintain the concentration of sulfur trioxide in the reaction mass at a low level hence, the addition of oleum to sulfur chloride rather than the reverse. When all of the reactants are added, heat is appHed to the jacket of the reactor and the batch is refluxed until most of the sulfur dioxide, hydrogen chloride, and chlorine are eliminated. The thionyl chloride is then distilled from the reactor. 

Sulfation. Sulfated castor oil, also known as turkey-red oil, represents one of the earliest chemical derivatives of castor oil. The traditional method of preparing turkey-red oil is to add concentrated sulfuric acid at a controlled rate to castor oil over a period of several hours with constant cooling and agitation of the reaction mass to maintain a temperature of 25—30°C. After acid addition is complete, the reaction mass is washed then neutralized using an alkaU solution or an amine. 

With batch reactors, it may be possible to add all reactants in their proper quantities initially if the reaction rate can be controlled by injection of initiator or acqustment of temperature. In semibatch operation, one key ingredient is flow-controlled into the batch at a rate that sets the production. This ingredient should not be manipiilated for temperature control of an exothermic reactor, as the loop includes two dominant lags—concentration of the reactant and heat capacity of the reaction mass—and can easily go unstable. 

Thus, if Ca and Cb can both be measured as functions of time, a plot of v/ca vs. Cb allows the rate constants to be estimated. (If it is known that B is also consumed in the first-order reaction, mass balance allows cb to be easily expressed in terms of Ca-) The rate v(Ca) is the tangent to the curve Ca = f(t) at concentration Ca-This can be determined graphically, analytically, or with computer processing of the concentration-time data. Mata-Perez and Perez-Benito show an example of this treatment for parallel uncatalyzed and autocatalyzed reactions. 

Sodium (9.6 parts) was dissolved in butanol (192 parts) and di-n-butyl ethyl 1 -methyl-n-butylmalonate (62,B parts) and urea (14.4 parts) were added to the warm solution with agitation. The mixture was then heated to reflux temperature in three quarters of an hour and maintained for 2 hours. The reaction mass was kept, water (150 parts) added, the aqueous portion separated, and the butanol layer extracted with water (3 x 50 parts). The combined aqueous extracts were then given 3 small extractions with benzene, the aqueous liquors separated, charcoaled,filtered and precipitated with concentrated hydrochloric acid (acid to congo-paper). The solid was collected, washed with water, dissolved in N-sodium hydroxide and reprecipitated with carbon dioxide. On recrystallization, from aqueous alcohol, the pentobarbitone was obtained. 

The equilibrium constant K (also called in the synthesis of PA-6) has also been found to be independent of the water concentration. Giori and Hayes30 found that with up to 0.5 mol water per kilogram of reaction mass (0.9 wt %), K increases linearly with water content (Fig. 3.14). At water concentrations higher than 1 mol kg-1 (1.8 wt %), K decreases again. At very high water concentrations, K seems to be independent of water content. 

A typical polymerization process as carried out on an industrial scale is given in Fig. 3.20.5 An autoclave (about 4 m3) is charged widi a concentrated PA salt solution in water (50% at 50°C). The autoclave is flushed with nitrogen and heated to 210°C while the pressure is allowed to increase to 18 bar. In this heating step, the salt concentration is increased to 75%. At 210°C, the reaction is carried out for 60 min. In die second step, the temperature is slowly increased to 280°C while maintaining the pressure at 18 bar. Subsequently, the reaction mass is warmed to 290°C and, at the same time, the pressure is lowered to atmospheric. At 290° C and at a slight pressure, the polymerization is continued for 1 h before the polymer is discharged. 

The present paper tests the assumed original and enhancement mechanisms with rates and conversions for a broad range of contaminants measured under a fixed mass concentration (50 mg/m ) feed condition. The plots compared are reaction rates vs. (1) dark adsorption, Ot. (2) second order rate constant for (OH ) (TCE absent) or (Cl ) (TCE present), and (3) the product of these gas phase second order rate constant times the reactant dark coverage. Where a second order gas phase rate constant was not available, we estimated its value from correlations of kci vs. koH for tke same class of compounds. 

Yield and other mass-related metrics such as atom economy, reaction mass efficiency and mass intensity have been examined by Constable et al with regard to their significance concerning greenness and costs. The importance of using a (product) concentration term, which can be mass intensity or mass index, is additionally emphasized by Laird et al This is in compliance with Winterton, who in his twelve more green chemistry principles demands the establishment of full mass balances. 

The reaction mass consists of two liquid phases and one solid phase no solvent is required. The major liquid phase is the crude amine product itself. The solid phase is promoted sponge nickel catalyst. Surrounding the catalyst is a second liquid phase consisting of concentrated caustic and water. Water and caustic are added continuously to make up for losses leaving in the crude product. The ratios of water, caustic, and catalyst in the reaction mass are controlled to produce high yields of product amine and very low catalyst usages. High catalyst concentrations are employed in the reaction mass to keep the concentration of unreacted nitriles very low the upper limit on the catalyst concentration is the point where the circulation rate is inhibited. 

The proposed mechanism of effect of surfactant and ultrasound is reported in Fig. 7.5. The long chain surfactant molecules attach to surface of nanoparticles due to physical adsorption. Only thin layer is adsorbed onto the CaC03 nanoparticles. Due to presence of ultrasound and use of surfactant will control the nucleation. Surfactant keeps the particles away from each other by preventing flocculation due to change in surface tension of reaction mass. The concentration of additives was changed from 0.2 to 1.0 g/L. Addition of 0.2 g/L tripolyphosphate shows the increase in the rate of precipitation which is determined from the Ca(OH)2 consumption. Polyacrylic acid shows the least rate of precipitation (0.115 mol/1), which... 

The acid is prepared by sulfonation of nitrobenzene with oleum, and the reaction product consists essentially of a hot solution of the acid in sulfuric acid. A completed 270 1 batch exploded violently after hot storage at 150C for several hours. An exotherm develops at 145°C, and the acid is known to decompose at 200 C [ 1], A similar incident arose from water leaking from a cooling coil into the fuming sulfuric acid reaction medium, which caused an exotherm to over 150°C and subsequent violent decomposition [2], Detailed examination of the thermal decomposition of the acid shows that it is much slower for the isolated acid than for the reaction mass, and that the concentration of sulfur trioxide in the oleum used for sulfonation bears... 

Figure 7.5. Concentration of gaseous feedstock 1 in a gas-ionic liquid biphasic reaction for slow (A) and fast (B) chemical reaction - mass transfer resistance on the gas side is neglected...

How can we express the equilibrium state of such a system A direct approach would be to write each reaction that could occur among the system s species, minerals, and gases. To solve for the equilibrium state, we would determine a set of concentrations that simultaneously satisfy the mass action equation corresponding to each possible reaction. The concentrations would also have to add up, together with the mole numbers of any minerals in the system, to give the system s bulk composition. In other words, the concentrations would also need to satisfy a set of mass balance equations. 

Analyses of the defect chemistry and thermodynamics of non-stoichiometric phases that are predominately ionic in nature (i.e. halides and oxides) are most often made using quasi-chemical reactions. The concentrations of the point defects are considered to be low, and defect-defect interactions as such are most often disregarded, although defect clusters often are incorporated. The resulting mass action equations give the relationship between the concentrations of point defects and partial pressure or chemical activity of the species involved in the defect reactions. 

The representation of the biological conservation of substrate to cell mass by an overall chemical reaction. The stoichiometric relationships are then used to calculate various rates such as cell mass concentration [83]. 

Two important variables must be considered when understanding gas-phase reactions in mass spectrometers time scales of reactions and concentration of reagents. 

The oil bath is removed, and, with the stirring maintained, the reaction mixture is cooled to room temperature by running cold water over the flask. Then 150 cc. of water is added to dissolve the reaction mass, and both layers of the mixture are transferred to a separatory funnel. An ice-cold solution of 25 cc. of concentrated sulfuric acid in 200 cc. of water is added, and the mixture is shaken vigorously. The ester layer is separated and washed with 200 cc. of water it is then shaken with successive 200-cc. portions of 5 per cent sodium bicarbonate solution until the evolution of carbon dioxide ceases, after which it is washed with 200 cc. of water. The bicarbonate solution is separated and extracted with 100 cc. of ether (Note 6). The ether extract,... 

Use of sensors to measure gas phase NO2 concentration, electrical conductivity of the reaction mass, and gas phase temperatures at several critical points in semi-continuous nitration reactors permits safe operation of nitration processes [10], The use of non-aqueous titration analysis in the control of nitration processes in explosives manufacture is discussed [11],... 

If ki is less temperature-dependent that 2, the optimum temperature profile is one that starts off at a high temperature to get the first reaction going but then drops to prevent the loss of too much B. Figure 3.10 sketches typical optimum temperature and concentration profiles. Also shown in Fig. 3.10 as the dashed line is an example of an actual temperature that could be achieved in a real reactor. The reaction mass must be heated up to 7. We will use the optimum temperature profile as the setpoint signal. 

For mass transfer with instantaneous chemical reaction the concentration profiles as schematically represented in Fig. B1 are assumed where the chemical reaction only takes place at plane f. Mass transfer is described by eq. (4) with i = A, B, C and s. At the left side of plane/ Ng = Xg = 0 (no B can pass plane /) and Nc = N, = Q (product and solvent are non-volatile). This results in the following difierential equations and associated boundary conditions ... 

FIGURE 3-6 Mass concentration of aerosol formation from olefin-ozone reaction as a function of olefin concentration, r, residence time in the flow reactor. Reprinted with permission from Burton et ai. 

The experimental crystallizer was a 350-mL jacketed glass unit that was provided with sufficient agitation to keep the contents well mixed. The compositions of the charges to the crystallizer were adjusted by adding the amino acids in predetermined ratios concentrations of the amino acid impurities were maintained in ranges comparable to those found in the recovery and purification of L-isoleucine from industrial fermentation reaction masses. The experiments were divided according to the mode of crystallization ... 

The first reaction provides a route for the reduction of alkyl halides since the carbo-cation (isopropyl, in Rl) may be prepared from action of AICI3 on the corresponding alkyl halide. Reactions of the type Rl are also important in the process, catalytic cracking, in the manufacture of gasoline. They have also been studied in mass spectro-metric experiments [235]. Reaction R2 is one route to the preparation of carbocations under stable ion conditions. Reaction R3 is employed in the laboratory synthesis of the tropylium cation. Reaction R4, the (crossed) Cannizzaro reaction, is unusual in that it takes place under strongly basic conditions. The oxy dianion is an intermediate in the reaction of concentrated hydroxide with the aldehyde, R HO. None of R1, R2, or R3 may have hydrogen atoms a to the carbonyl groups. Formaldehyde (R1 = H) is readily... 

Because atmospheric humidity must be avoided, the reaction flask is isolated from the atmosphere with drying tubes. Moreover, since the solvent is rarely perfectly anhydrous and will contain traces of water due to its hygroscopic nature, its water content must be measured prior to the determination. The equivalence point of the titration reaction is detected by an electrical method instead of a visual method. The current intensity that passes between two platinum electrodes inserted in the reaction medium is measured (see Fig. 19.10). The reagent, which is a mixture of sulphur dioxide, iodine and a base, is characterised by the number of mg of water that can be neutralised by 1 cm3 of this reagent. This is referred to as the equivalent mass concentration of water, or the titre T of the reagent. 

---