Calcium chloride drying tube

Method B. In a 500 ml. round-bottomed flask, provided with a reflux condenser protected by a cotton wool (or calcium chloride) drying tube, place 59 g. of succinic acid and 102 g. (94-5 ml.) of redistilled acetic anhydride. Reflux the mixture gently on a water bath with occasional shaking until a clear solution is obtamed ca. 1 hour), and then for a further hour to ensure the completeness of the reaction. Remove the complete assembly from the water bath, allow it to cool (observe the formation of crystals), and finally cool in ice. Collect the succinic anhydride as in Method A. The yield is 45 g., m.p. 119-120°. 

Mix together in a 250 ml. flask carrying a reflux condenser and a calcium chloride drying tube 25 g. (32 ml.) of freshly-distilled acetaldehyde with a solution of 59-5 g. of dry, powdered malonic acid (Section 111,157) in 67 g. (68-5 ml.) of dry pyridine to which 0-5 ml. of piperidine has been added. Leave in an ice chest or refrigerator for 24 hours. Warm the mixture on a steam bath until the evolution of carbon dioxide ceases. Cool in ice, add 60 ml. of 1 1 sulphuric acid (by volume) and leave in the ice bath for 3-4 hours. Collect the crude crotonic acid (ca. 27 g.) which has separated by suction filtration. Extract the mother liquor with three 25 ml. portions of ether, dry the ethereal extract, and evaporate the ether the residual crude acid weighs 6 g. Recrystallise from light petroleum, b.p. 60-80° the yield of erude crotonic acid, m.p. 72°, is 20 g. 

Coumarin. In a 250 ml. round-bottomed flask, provided with a small reflux condenser and a calcium chloride drying tube at the top, place 2 1 g, of salicylaldehyde, 2 0 ml. of anhydrous triethylamine and 5 0 ml. of acetic anhydride, and reflux the mixture gently for 12 hours. Steam distil the mixture from the reaction flask and discard the distillate. Render the residue in the flask basic to litmus with solid sodium bicarbonate, cool, filter the precipitated crude coumarin at the pump and wash it with a little cold water. Acidify the filtrate to Congo red with... 

Alternatively, use the following procedure in which triethylamine replaces potassium acetate as the basic catalyst. Place 2 1 g. (2-0 ml.) of purified benzaldehyde, 2 0 ml. of anhydrous triethylamine and 5 0 ml. of A.R. acetic anhydride in a 200 ml. round-bottomed flask, equipped with a short reflux condenser and a calcium chloride drying tube. Boil the solution gently for 24 hours—heating may be interrupted. Incorporate a steam distillation apparatus in the flask and steam distil until the distillate is no longer cloudy (about 100 ml.) and then collect a further 50 ml. of the distillate di ard the steam distillate. Transfer the residue in the flask to a 400 ml. beaker, add water until the vplume is about 200 ml., then 0 2 g. of decolourising carbon, and boil for a few minutes. Filter the hot solution, and acidify the hot filtrate with 1 1 hydrochlorioiaoid... 

B. Ethyl l-( p-methoxyphenyl I-2-oxoayotohexaneaar hoxylate. A 250 mL, one-necked, round-bottomed flask, equipped with a magnetic stirring bar, is charged with 22.2 g (45 mmol) of p-methoxyphenyl 1 ead triacetate, 10.8 g (135 mmol) of pyridine (Note 8), and 70 mL of chloroform (Note 9). To this solution 1s added 7.0 g (41 mmol) of ethyl 2-oxocyclohexanecarboxylate (Note 10), a calcium chloride drying tube Is put 1n place, and the mixture is stirred at 40°C (Note 11). 

C. Pyocyanine alkylation). A solution of 2 g. (0.011 mole) of a-hydroxyphenazine in 13.4 g. (10 ml., 0.1 mole) of methyl sulfate (Note 10) is placed in a 250-ml. Erlenmeyer flask fitted with a calcium chloride drying tube and heated at 100° (oil bath) for 10 minutes. The solution is allowed to cool to room temperature, and about 7.5 ml. of dry ether is added. The dark brown solid is filtered on a 7-cm. Eiichner funnel and washed with about ISO ml. of dry ether in several portions (Note 11). 

A mixture of 50 g. (0.26 mole) of anhydrous stannous chloride and 225 ml. of dry ether is placed in a 1-1. three-necked round-bottomed flask fitted with a rubber-tube sealed stirrer, an inlet tube reaching nearly to the bottom of the flask, and a reflux condenser (Note 2) protected by a calcium chloride drying tube. The mixture is saturated with dry hydrogen chloride (Note 3) with continuous stirring. Within 3 hours all the stannous chloride dissolves, forming a clear viscous lower layer. The source of hydrogen chloride is then disconnected, and the freshly prepared imidyl chloride is transferred into the mixture with the aid of 25 ml. of dry ether (Note 4). Stirring is continued for 1 hour, and then the reactants are allowed to stand at room temperature for 12 hours. 

A. Bis i-methoxyphenyl)tellurium Dichloride. In a dry, 500-ml., three-necked, round-bottomed flask equipped with a thermometer and a reflux condenser fitted with a calcium chloride drying tube are placed 27.0 g. (0.1 mole) of tellurium tetrachloride (Note 1) and 64.8 g. (0.6 mole) of dry anisole (Note 2). The mixture is heated to 160 over a period... 

B. (l-Azido-3,3-dimethoxy-l-propenyl)benzene. In a 2-1., one-necked, round-bottomed flask equipped with a magnetic stirrer and powder funnel are placed 156 g. (0.45 mole) of the iodoazide from Part A and 1500 ml. of anhydrous ether. The solution is stirred and cooled in an ice-salt bath (— 5° to 0°), and 62 g. (0.55 mole) of potassium <-butoxide (Note 6) is added. The powder funnel is then replaced by a calcium chloride drying tube and the mixture is stirred for 4 5 hours at 0°. At the end of this time 350 ml. of water is added while the mixture is still cold. The ethereal layer is then separated and washed with three 350-ml. portions of water and dried over magnesium sulfate. The solvent is removed with a rotary evaporator without heating, leaving 67-75 g. (68-76%) of (l-azido-3,3-dimethoxy-l-propenyl)-benzene as a dark oily liquid (Note 7). This material can be used without further purification for Part C (Note 8). 

Hydroxy-B-homo-choIest-5-en-7a-one Acetate (67) A solution of 3p-hydroxycholest-5-en-7-one acetate (57 0.45 g) in absolute ether (140 ml) is placed in a 500 ml two-necked flask equipped with a mechanical stirrer and a calcium chloride drying tube. An ether solution of diazomethane (15.4 ml 0.42 g = 0.01 mole) is added with stirring at room temperature. Aluminum chloride (50 mg) is then added to the stirred solution. After 5 min an additional 50 mg of aluminum chloride is added. 

B. 2-Cyclohexyloxyethanol. A well-dried, 3-1. three-necked, round-bottomed flask is equipped with a stirrer, a pressureequalizing dropping funnel, and a condenser to whose top is attached a calcium chloride drying tube. The flask is charged with 242 g. (1.81 moles) of anhydrous aluminum chloride powder and is immersed in an ice-salt bath. Anhydrous ether (25-50... 

A. N,N-Dimeihyljormamide-dimelhyl sulfate complex. In a 500-ml. four-necked flask equipped with mechanical stirrer, reflux condenser with calcium chloride drying tube, dropping funnel, and thermometer is placed 73 g. (1.0 mole) of dimethyl-formamide, and 126 g. (1.0 mole) of dimethyl sulfate is added dropwise with stirring at 50-60° (Note 1). After the addition is complete, the mixture is heated for another 2 hours at 70-80°. The dimethylformamide complex forms as a viscous, colorless or pale yellow ether-insoluble oil. 

B. 2-Acetyl-6,l-dimethoxy-l-methylene-l,2,3,4-tetrahydroisoquinoline [Isoquinoline, 2-acetyl-l,2, A,4-tetrahydro-6,7-dimethoxy-l-methylene-]. A 1-1., three-necked, round-bottomed flask equipped with a mechanical stirrer, a reflux condenser topped with a calcium chloride drying tube, and a thermometer is charged with 110 ml. of acetic anhydride, 110 ml. of pyridine, and 45.0 g. (0.22 mole) of the dihydroisoquinoline prepared in Part A. The reaction mixture is stirred and heated at 90-95° for 30 minutes, stored at room temperature overnight, and concentrated by distillation at 50° using a rotary evaporator. The residue is diluted with 20 ml. of ethyl acetate, and another evaporation under reduced pressure gives material that can be crystallized from 75 ml. of ethyl acetate to yield 38.5 41.0 g. (72-77%) of product, m.p. 106-107° (Note 11). 

A. Dipotassium Salt of Xitroacelic Acid. A 3-1., three-necked, round-bottomed flask equipped with a sealed mechanical stirrer, a condenser Fitted with a calcium chloride drying tube, and a pressure-... 

A. 2,3-Dibromopropionaldehyde diethyl acetal. A 500-ml., three-necked, round-bottomed flask is equipped with a mechanical stirrer, a pressure-equalizing dropping funnel fitted with a calcium chloride drying tube, and a thermometer. The flask and dropping funnel are charged with 28.0 g. (0.5 mole) of freshly distilled acrolein and 80.0 g. (0.5 mole) of bromine, respectively. The acrolein is stirred rapidly and cooled to 0° in an ice-salt bath, then bromine is added at a rate such that the temperature is kept at... 

A. 2-Hydroxyimino-2-phenylacetonitrile. A 1-1., round-bottomed flask is fitted with a mechanical stirrer, a calcium chloride drying tube, a thermometer, and a gas-inlet tube. In the flask are placed 117 g. (1.0 mole) of benzyl cyanide and a solution of 40.0 g. (1.0 mole) of sodium hydroxide in 300 ml. of methanol (Note 1). The resulting solution is stirred and cooled at 0° as methyl nitrite is introduced through the gas-inlet tube, which extends below the surface of the liquid. The methyl nitrite is generated by dropwise addition of a cold solution of 32 ml. of concentrated sulfuric acid in 65 ml. of water from a 100-ml., pressure-equalizing dropping funnel into a 300-ml. Erlenmeyer flask containing a suspension of 83 g. (1.2 moles) of sodium nitrite... 

---