Boiling under reflux

When concentrated sulphuric acid is added to ethanol, the mixture becomes hot owing to the formation of ethyl hydrogen sulphate, the yield of which is increased if the mixture is then gently boiled under reflux ... 

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. 

The toluene-p sulphon-dimethylamide can be readily hydrolysed by boiling under reflux with 70% sulphuric acid (see p. 107). If the... 

The aniline and the monomethylaniline can be obtained from their respective sulphonyl derivatives by hydrolysis with 70% sulphuric acid (preparation, p. 109), the mixture of the sulphonyl compound and the acid being gently boiled under reflux to illustrate the separation of the three amines, however, this is not necessary. 

B) Methiodi s. Members of Classes (i), (ii) and (iv) combine wdth methyl iodide (some very vigorously) to form quaternary methiodides. It is best to add the amine to an excess of methyl iodide dissolved in about twice its volume of methanol, allow any spontaneous reaction to subside, and then boil under reflux for 30 minutes (extend to 1 hour for Class (iv) except pyridine and quinoline). The methiodide may crystallise when the reaction-mixture cools if not, evaporate the latter to small bulk or to dryness, and recrystallise, (M.ps., pp. 553-554 )... 

Weigh out approximately 1 5 g. of powdered pentacetylglucose (p. 141) in the flask A, and then add 25 ml. of M H2S04 solution to each of the flasks A and B, together with a fragment of porcelain. Boil under reflux gently for 30 minutes, then wash each condenser down as before with 10 ml. of distilled water, cool, and titrate the solutions with A/.NaOH solution. 

Potassium Hydroxide, Alcoholic. Boil under reflux a mixture of 10 g. of powdered KOH and 100 ml. of rectified spirit for 30 minutes. Cool and if solid material remains, decant through a filter of glass-wool. 

J The hexa.acetyl derivative, m.p. 121°, may be prepared as follows. Boil under reflux 1 part of mannitol with 5 parts by weight of acetic anhydride and 1 part of anhydrous sodium acetate or with a little anhydrous zinc chloride for 15-20 minutes, pour into excess of water, stir the mixture until the oil has solidifled, and then recrystallise from methylated spirit. 

To 100 ml. of rectified spirit in a 250 ml. round-bottomed flask add 8 g. of benzamide and 10 g. of finely-powdered mercuric oxide. Boil under reflux for 30 minutes and filter the hot solution through a fluted filter paper to remove unreacted mercuric oxide. If the first portion of... 

Dibromo-o-cresolsulphonephthalein (bromocresol purple). Dissolve 6 g. of o-cresolsulphonephthalein in 50 ml. of glacial acetic acid, heat to boiling under reflux, add slowly a solution of 2 ml. of bromine in... 

In order to secure a pure product the above material is dissolved in 175 cc. of tetrachloroethane by boiling and the solution is boiled under reflux for fifteen minutes with 12 g. of decolorizing carbon, and then filtered by suction into an Erlenmeyer flask, washing the charcoal with about 50 cc. of hot solvent. The filtrate is kept hot, treated with 750 cc. of boiling alcohol, and set aside to crystallize. The benzanthrone separates as pure yellow needles melting at r7o-i7r° yield, 48-52 g. (60-65 per cent of the theoretical amount) (Note 7). 

A mixture of 105.6 g. (1.1 moles) of freshly distilled furfural, 87.0 g. (1.0 mole) of 98% cyanoacetic acid (Note 1), 3.0 g. of ammonium acetate, 200 ml. of toluene, and 110 ml. of pyridine is placed in a 1-1. round-bottomed flask equipped with a Stark and Dean water trap and reflux condenser. The mixture is boiled under reflux for 2 days. The theoretical quantity of water is collected in the trap within 1 hour. Upon completion of the reflux period, the solvent is removed under reduced pressure by heating on a water bath. The residue, distilled through a 15-cm. Vigreux column at 11 mm. pressure, yields 88.6-93.3 g. (74.5-78%) of colorless liquid boiling at 95-97°, 1.5823-1.5825. 

While keeping the collected deuterioammonia at dry ice-isopropyl alcohol temperature, lithium wire (10 mg) is added, followed by a solution of 3/3-hydroxy-5a-cholest-7-en-6-one (161 50 mg) in anhydrous tetrahydrofuran (4 ml). The reaction mixture is stirred for 20 min, the cooling bath is then removed and the ammonia is allowed to boil under reflux for 40 min. A saturated solution of ammonium chloride in tetrahydrofuran is added dropwise until the deep blue color disappears and then the ammonia is allowed to evaporate. The residue is extracted with ether and the organic layer washed with dilute hydrochloric acid and sodium bicarbonate solution and then with water. Drying and evaporation of the solvent gives a semicrystalline residue which is dissolved in acetone and oxidized with 8 N chromic acid solution. After the usual workup the residue is dissolved in methanol containing sodium hydroxide (0.2 g) and heated under reflux for 1 hr to remove any deuterium introduced at C-5 or C-7. (For workup, see section II-B). 

Aminocephalosporanic acid (5.00 g) which passed through a 100-mesh sieve was suspended in boiling ethyl acetate (200 ml), and 2-thienylacetyl chloride (Cagniant, Bull. Soc. Chim. France, 1949,847) (4.42 g, 1.5 equiv.) was added in ethyl acetate (20 ml). The mixture was boiled under reflux for 40 minutes, cooled, and filtered. Aniline (5.03 ml) was added, and after 1 hour the mixture was extracted with 3% sodium hydrogen carbonate solution (1 x 150 ml, 2 X 100 ml, 1 x 50 ml) and the alkaline extracts washed with ethyl acetate (3 x 100 ml). The aqueous solution was acidified to pH 1.2, and extracted with ethyl acetate (2 x 150 ml). The ethyl acetate extract was washed with water (4 x 40 ml), dried (MgS04), and concentrated in vacuo to low volume. The crude 7-2 -thienylacetamidocephalosporanic acid (2.5 g) which separated was collected by filtration. Evaporation of the filtrate gave a further 2.68 g (71%) of the product, which was purified by crystallization from ethyl acetate, then aqueous acetone, MP 150°Cto 157°C (decomp.). 

A mixture of 31 5 g (0.1 mol) of 2-chloro-9-(3 -dimethylaminopropylidene)-thiaxanthene (MP 97°C) and 100 g of N-( 3-hydroxyethyl)-piperazine is heated to 130°C and boiled under reflux at this temperature for 48 hours. After cooling, the excess of N-( 3-hydroxyethyl)-piperazine Is evaporated in vacuo, and the residue is dissolved in ether. The ether phase is washed with water and extracted with dilute acetic acid, and 2-chloro-9-[3 -N-(N - -hydroxy-ethyD-piperazinylpropylidene] -thiaxanthene separated from the aqueous acetic acid solution by addition of dilute sodium hydroxide solution to basic reaction. The free base is extracted with ether, the ether phase dried over potassium carbonate, the ether evaporated and the residue dissolved in absolute ethanol. By complete neutralization of the ethanolic solution with a solution of dry hydrogen chloride in absolute ethanol, the dihydrochloride of 2-chloro-9-[3 -N-(N -(3-hydroxyethyl)-piperazinylpropylidene] -thiaxanthene is produced and crystallizes out as a white substance melting at about 250°C to 260°C with decomposition. The yield is 32 g. 

The manufacture of a related compound is first described. 28.1 parts of p-chloro-benzhy-dryl bromide are heated to boiling, under reflux and with stirring, with 50 parts of ethylene chlorohydrin and 5.3 parts of calcined sodium carbonate. The reaction product is extracted with ether and the ethereal solution washed with water and dilute hydrochloric acid. The residue from the solution in ether boils at 134° to 137°C under 0.2 mm pressure and is p-chloro-benzhydryl-(/3-chloroethyl) ether. 

A mixture of 17.6 grams of p-n-butoxyacetophenone, 12.1 grams of piperidine hydrochloride, 4.5 grams paraformaldehyde, 0.25 cc concentrated hydrochloric acid, 52.5 cc nitro-ethane, 7.5 cc of 95% ethanol, and 15 cc of toluene was boiled under reflux for one hour, removing water formed in the reaction by means of a condensate trap. The mixture was then cooled. The crystals which formed were collected by filtration, washed with anhydrous ether and recrystallized from methyl ethyl ketone. The crystals thus obtained, which melted at 174°-175°C, were shown by analysis to be 4-n-butoxy-beta-piperidinopropiophen-one hydrochloride. 

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