Total reaction time

The end of the reaction is indicated by the pressure and temperature observations. The total reaction time is of the order of 16-18 hours. 

A sample of commercial furfural is purified by simple distillation or steam distillation immediately before use. The submitters have carried out this reaction on an 8-mole scale following the same procedure except that a total reaction time of about 4 hours was required. 

If the total reaction time is less than approximately 1.75 hours, starting material remains. Therefore, if the ethereal hydrogen chloride is added in less than 1.5 hours, the subsequent stirring must be lengthened accordingly. 

Synthesis of N,N -bis(p-carbomethoxybenzoyl) butanediamine (T4T-dimethyl). Dimethyl terephthalate (DMT) (275 g, 1.42 mol) is dissolved at 65°C in a mixture of 1100 mL anhydrous toluene and 85 mL anhydrous methanol in a 2-L flask equipped with a stirrer, condenser, calcium chloride tube, and nitrogen inlet. When all the DMT is dissolved, 15 mL lithium methoxide (1.25 M) is added. 1,4-Butanediamine (BDA) (34 mL, 0.34 mol), dissolved in 150 mL anhydrous toluene and 10 mL anhydrous methanol, is added dropwise in 4-6 h while the nitrogen flow is stopped. Three hours after the start of the BDA addition, the temperature is gradually increased up to 90°C (5°C/h) while the methanol is stripped off. After a total reaction time of 24 h the reaction is stopped. The white... 

At higher water concentrations (at higher pressure) (Fig. 3.24), the reaction is considerably more rapid. The prepolymer obtained is further polymerized in another reactor, which has a working pressure of 1 bar or less. The total reaction time of the prepolymerization can be considerably shortened by processing it in an autoclave.812 28 In a laboratory, PA-6 can be synthesized in several ways from m-aminocaprolic acid, from lactam and from lactam and water, and anionically. 

A 250-mL, two-necked, round-bottomed flask equipped with a magnetic stirbar, thermometer, and a reflux condenser fitted with a rubber septum and balloon of argon is charged with a solution of methyltrioxorhenium (MTO) (0.013 g, 0.05 mmol, 0.1% mol equiv) in 100 mL of methanol (Note 1). Urea hydrogen peroxide (UHP) (14.3 g, 152 mmol) is added (Notes 1, 2, 3, 4), the flask is cooled in an ice bath, and dibenzylamine (9.7 mL, 50.7 mmol) is then added dropwise via syringe over 10 min (Notes 1, 5). After completion of the addition, the ice bath is removed and the mixture is stirred at room temperature (Note 6). A white precipitate forms after approximately 5 min (Note 7) and the yellow color disappears within 20 min (Note 8). Another four portions of MTO (0.1% mol equiv, 0.013 g each) are added at 30-min intervals (2.5 hr total reaction time). After each addition, the reaction mixture develops a yellow color, which then disappears only after the last addition does the mixture remain pale yellow (Note 9). The reaction flask is cooled in an ice bath and solid sodium thiosulfate pentahydrate (12.6 g, 50.7 mmol) is added in portions over 20 min in order to destroy excess hydrogen peroxide (Note 10). The cooled solution is stirred for 1 hr further, at which point a KI paper assay indicates that the excess oxidant has been completely consumed. The solution is decanted into a 500-mL flask to remove small amounts of undissolved thiosulfate. The solid is washed with 50 mL of MeOH and the methanol extract is added to the reaction solution which is then concentrated under reduced pressure by rotary evaporation. Dichloromethane (250 mL) is added to the residue and the urea is removed by filtration through cotton and celite. Concentration of the filtrate affords 10.3 g (97%) of the nitrone as a yellow solid (Note 11). 

Condensation reactions are somewhat more difficult to study by the pulsing technique since the secondary ion usually has a considerably higher mass than the primary ion. However, by restricting the total reaction time to 1 nsec, or less, we have found it possible to study this type of reaction under thermal conditions. Preliminary results are presented in Table IV. Many of the product ions in these systems can be formed in more than one reaction, and the details of reaction identification will be presented elsewhere. 

The orders, ne i and nB2. will determine whether Cg should be maintained high or low in the reactor. The total reaction time must be adjusted such that P is... 

Figure 3.10 Reaction Conversion vs. Time Figure 3.11 Effect of Initial Substrate at Various Initial Substrate Charges. Charge on Total Reaction Time.

In some fluid-solid reactions, nucleation of the product constitutes an important step. With increasing size of the solid or with increasing reaction temperature, the time within which nucleation is important becomes small compared to the total reaction time, thereby making nucleation relatively less important. 

In a 1-1. round-bottomed flask, fitted with a heated reflux condenser maintained at 100-110° (Note 1), are placed 44 g. of stearic acid (Note 2) and 20 g. (0.5 mole) of magnesium oxide (Note 3). The flask is immersed in a Wood s metal bath heated at 335-340° (Note 4). After the reaction has proceeded for 1 hour, 10-g. portions of melted stearic are added down the condenser at 15-minute intervals until an additional 240 g. (284 g., 1 mole total) has been added (Note 5). The heating is continued until the total reaction time is 10 hours. 

The temperature of the reaction mix was measured by a stainless steel-sheathed thermocouple inserted through the reactor cap. Heating up and cooling down times were small compared with the total reaction time. In all cases the free space in the reactor was flushed with nitrogen before sealing, and the reaction proceeded under a small initial nitrogen pressure. 

Note 12). After a total reaction time of 30 minutes (Note 13), during which the mixture has become almost solid and is very difficult to stir, the material is filtered hot (Note 14). The yield of 3,5-dibromosulfanilamide is 85-90 g. (90-94%), and the crude tan product (Note 15) melts over a range of 1-2° in the region 230-237° (Note 16). 

The slow water removal is obvious within the synthesis of, for example, myristyl myristate determining the total reaction time. In a stirred-tank reactor it takes 24 h to reach a conversion of 99.6% and in a fixed-bed reactor 14 h. Therefore, a new synthesis platform (Figure 4.11) which also enables conversion of highly viscous polyols and fatty acids from renewable resources to ester-based surfactants was designed. It is used by Evonik on a pilot scale, outperforming conventional methods, such as stirred-tank or fixed-bed reactors. In contrast to the setups introduced before, conversion of >99.6% is already obtained after 5.5 h in the bubble column reactor [44-47]. 

The nitrile-hydrolyzing activity of Ar throb act er spp. NS SC 104 was shown to be resistant to the suppressing effect of a-hydroxy nitriles such as lactonitrile and HMTBN, and accumulated the corresponding a-hydroxy acid ammonium salt at a high concentration [77]. HMTBN (200 him) was added to a suspension of Ar throb act er spp. NSSC 104 cells (4% dew) in phosphate buffer (0.1 m, pH 7.5) and mixed at 30 °C seven more additions of the same amount of HMTBN were added at 1 h intervals, then a further eight additions made at 1.5 h intervals over a total reaction time of 19 h. At completion of the reaction, the concentration of 2-hydroxy-4-methylthiobutyrate... 

Using conventional heating each step involved heating at 170 °C for 10 min, giving an overall radiochemical yield of 40-60%. In contrast, MW heating in a closed Pyrex tube gave a radioactivity gain of 91 % in a total reaction time of 1 min. 

If desired, the course of the reaction may be followed by means of the optical density of the reaction mixture at 235 m/. The ultraviolet spectrum of isophorone has a maximum at 235 mp (e 13,300) the ultraviolet spectrum of isophorone oxide has a maximum at 292 mju (e 43). A total reaction time of 4 hours under the conditions specified was found to be ample for the complete conversion of isophorone to its oxide. If the conversion is not complete, the product cannot be separated from the unchanged isophorone without recourse to precise fractional distillation. The absence of isophorone from the final product may be verified by examination of the spectrum at 235 mp. 

The total reaction time has varied greatly over several runs from 2-6 hr. The head temperature during the reaction rises slowly and appears to depend on how steadily the product distills. Occasionally, the head temperature has reached only 70°C, but the purity of the product was >98% by GC and 1H NMR analysis. In three attempts, the checkers found the distillation to be long, in no instance less than 5 hr and once 9 hr. Users should heed the precaution in Note 15. 

PhNHSCLOR Acylating agent Solvent Addition time Total reaction time % yield... 

The experiments undertaken at LANL were carried out in a 2-L Parr reactor charged with 1 kg of caustic solution and 10 percent energetics at 93°C (versus 87°C at HAAP). In contrast to the experiments at HAAP, the energetic material was introduced into the caustic at ambient temperature before heating. The heating from ambient to 93°C typically took about 40 minutes. The reaction temperature was maintained with vigorous stirring set at 720 rpm until the total reaction time reached 100 min. 

A total reaction time of 30 min is needed for more stericaHy... 

Molten sodium tetrachloroaluminate (a 1 1 mixture of NaCl and AICI3) is a good reaction medium for the Friedel-Crafts acylation reaction given in fig. 3.3 (Wade et al., 1979). Whereas the classical procedure for the synthesis of 1-indane from 3-phenylpropanoic acid consists of three reaction steps with a total reaction time of ca. six hours (Gattermann et al., 1982), the molten salt reaction is finished in five minutes and gives an even better yield (Wade et al., 1979). 

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