Reflux cooling

To prepare the potassium salt, the mixture of ethanol and sulphuric acid is boiled under reflux, cooled, and treated with an excess of calcium carbonate. 

NaBH4 has also been crystd from isopropylamine by dissolving it in the solvent at reflux, cooling, filtering and allowing the solution to stand in a filter flask connected to a Dry-ice/acetone trap. After most of the solvent was passed over into the cold trap, crystals were removed with forceps, washed with dry diethyl ether and dried under vacuum. [Kim and Itoh J Phys Chem 91 126 1987.] Somewhat less pure crystals were obtained more rapidly by using Soxhlet extraction with only a small amount of solvent and extracting for about 8h. The... 

A solution of 12.5 g (0.088 mole) of l,4-dioxaspiro[4.5]decane (Chapter 7, Section IX) in 200 ml of anhydrous ether is added to the stirred mixture at a rate so as to maintain a gentle reflux. (Cooling in an ice bath is advisable.) The reaction mixture is then refluxed for 3 hours on a steam bath. Excess hydride is carefully destroyed by the dropwise addition of water (1-2 ml) to the ice-cooled vessel until hydrogen is no longer evolved. Sulfuric acid (100 ml of 10% solution) is now added followed by 40 ml of water, resulting in the formation of two clear layers. The ether layer is separated and the aqueous layer extracted with three 20-ml portions of ether. The combined ethereal extracts are washed with saturated sodium bicarbonate solution followed by saturated sodium chloride solution. The ethereal solution is dried over anhydrous potassium carbonate (20-24 hours), filtered, and concentrated by distillation at atmospheric pressure. The residue is distilled under reduced pressure affording 2-cyclohexyloxy-ethanol as a colorless liquid, bp 96-98°/ 3 mm, 1.4600-1.4610, in about 85% yield. 

The process employed in carrying out this invention is as follows A mixture of 1 to IJ parts acetone (45 kg.), 1 part of lemon-giass oil (38 kg.), IJ to 2 parts of alcohol (75 kg.), 1 to 2 parts of a concentrated lime-free solution of chloride of lime (75 kg.), to which is added a little cobaJtous nitrate (30 gr.) dissolved in water, is boiled during six to eighteen hours at a temperature of 70° to 80° C. in a reflux cooling apparatus. 

As can be seen, the principal differences of this process from the earlier German process includes a) reflux cooling of the first reaction zone, b) the possible division of the first reaction zone into a series of CSTR s and c) the incorporation of a devolatilization step. 

This patent then calls for two or more reflux cooled conical CSTR s with helical ribbon agitators operating in series in an "intermediate conversion zone" ranging from 65 to 85% conversion. The conversion in succeeding reactors in this zone should show a relative difference of 15-25%. As with the earlier patent,... 

Monsanto Patents. A process for HIPS is described in the patent issued to Carter and Simon (35)and is illustrated in Fig. 20. There are two reactors an anchor agitated CSTR and a reflux cooled LFR. Both reactors can be operated at variable and controllable tillage so that a given product can be made over a range of rates. 

The reactor operates with the effluent at about 166 C and 62% conversion. Temperature control is effected primarily by reflux cooling as indicated in Fig. 20 with the condensed vapors being returned to the upstream reactor compartment. 

A 50-ml egg-type flask equipped with a reflux cooling tube and a stirrer bar was charged with the step 2 product (0.0543 mol) and then treated with formic acid (0.380 mol) and sulfuric acid (0.0136 mol) and heated to 100°C for 2 hours. The... 

Method 2, Dissolve the sample in aq methanol, add KOH and gently reflux. Cool the soln and add aq HC1, followed by stannous chloride ... 

C were suspended in toluene/CH2Cl2 (40 mL, 50/50 v/v%) and 3-aminopropyltriethoxysilane (0.88 mL, 0.00379 mol) was added. The mixture was heated overnight at reflux, cooled, and filtered to recover the aminopropyl-APMS, which were then washed with toluene and MeOH. These were then reacted with R-(-)-3,5-dinitrobenzoyl-a-phenylglycine (2.657 g, 0 0075 mol) in toluene/CH2Cl2 (40 mL, 50/50 v/v%) to which N-ethoxycarbonyl-2-ethoxy-l,2-dihydroquinoline (0.875 g, 0 0075 mol) had been added to catalyze the reaction. After stirring overnight, the solid was recovered by filtration and washed with toluene and MeOH to afford the product as a yellow powder (2 792 g). 

The vaporization of the extra reflux cools the tray. The extra vapor generated adds to the vapor flow from the tray. This increases the vapor flow from the tray. Even though the heat flow into the tower is constant, increasing the top reflux does increase the pounds of vapor flowing up the tower. 

An ethereal solution of methyllithum (84 mL of 1.0 M solution, 84 mmol as close to a 3 1 ratio as possible) is added dropwise, and the solution is heated under reflux, cooled, and filtered as described for the trimethyl indium preparation. Toluene (70 mL), dppe (5.53 g, 13.9 mmol), and a stirrer bar are... 

A third method is reflux cooling by a condenser mounted on top (Figure 10). This type of cooling is very effective. On the 200-m3 reactor heat rates of up to 15 million kcal/hour can be removed. Boiling conditions must prevail in the reactor, and some restrictions must be observed ... 

A reliable control of the reaction course can be obtained by isothermal operation. Nevertheless, to maintain a constant reaction medium temperature, the heat exchange system must be able to remove even the maximum heat release rate of the reaction. Strictly isothermal behavior is difficult to achieve due to the thermal inertia of the reactor. However, in actual practice, the reaction temperature (Tr) can be controlled within 2°C, by using a cascade temperature controller (see Section 9.2.3). Isothermal conditions may also be achieved by using reflux cooling (see Section 9.2.3.3), provided the boiling point of the reaction mass does not change with composition. 

Can the reaction heat be removed by reflux cooling using (i) water ... 

The resulting mixture was heated under reflux, cooled, and stirred with water. The dichloromethane layer was separated, washed with dilute aqueous potassium carbonate until neutral, water, and dried (MgS04) and evaporated to give 4-(4-chlorophenyl)-l,2-epoxybutane as a colorless oil. 

A mixture of 100 parts of N-p-chloroethyl-N-benzylaniline and 100 parts of freshly distilled pyrrolidine are heated to boiling under reflux cooling for about 10 h. Diluted aqueous caustic soda lye is added to the reaction mixture until it shows an alkaline reaction. The reaction product formed and unchanged pyrrolidine are extracted with ether. The extract thus obtained is a subjected to a distillation. After the ether has evaporated, there is produced N-(p-N-phenyl-N-benzylaminoethyl)pyrrolidine, which boils at from 198° to 205°C under 1 mm pressure. 

Under an atmosphere of argon, a mixture of 7.5 mg of rhodium trichloride, 30.0 mg of tris-(hexylphenyl)-phosphine, 3 ml of acetone and 15 ml of hydrazine hydrate is heated with stirring and reflux cooling for 4 hours. 

Portion 1 The solution was evaporated to give a black oil which was partitioned between water (200 ml) and chloroform (200 ml). The separated chloroform phase was washed with saturated brine, then dried over magnesium sulphate, filtered and evaporated to give a reddish oil which was dissolved in acetone (200 ml), boiled under reflux, cooled to 40°C and then seeded with nizatidine. The mixture was left to stand at 0°-5°C for 64 hours. The mixture was filtered to give nizatidine (10.4 g, 37%) m.p. 118-122°C. 

Acetoxy-3-chloropropyl Tellurium Trichloride7 In 20 ml of chloroform at 20° stirred overnight are 2.55 g (9.5 mmol) of tellurium tetrachloride and 0.96 g (9.6 mmol) of 3-acetoxypropene. The mixture is then heated to reflux, cooled to 20°, filtered, the filtrate is evaporated to dryness, and the residue is recrystallized from carbon tetrachloride yield 3.4 g (97%) m.p. 91°. 

---