Calcium mixing

Fig. 1. Kinetics of the reaction of aequorin with calcium mixed in a stopped-flow...

Surface water Is usually undersaturated in calcium ions (Ca ). Where (even saturated) surface water mixes with sea water, mixing zone corrosion will dissolve calcium carbonate. Evidence of this occurring may be seen on islands. 

Industrially. phosphoric(V) acid is manufactured by two processes. In one process phosphorus is burned in air and the phos-phorus(V) oxide produced is dissolved in water. It is also manufactured by the action of dilute sulphuric acid on bone-ash or phosphorite, i.e. calcium tetraoxophosphate(V). Ca3(P04)2 the insoluble calcium sulphate is filtered off and the remaining solution concentrated. In this reaction, the calcium phosphate may be treated to convert it to the more soluble dihydrogenphosphatc. CafHjPOjj. When mixed with the calcium sulphate this is used as a fertiliser under the name "superphosphate . 

The gases from the kiln contain about 9% sulphur dioxide. (The calcium oxide combines with the silica to form a silicate slag which, when cool, is crushed and mixed with some anhydrite to give cement, a valuable by-product.)... 

Mix 40 g. (51 ml.) of isopropyl alcohol with 460 g. (310 ml.) of constant boiling point hydrobromic acid in a 500 ml. distilling flask, attach a double surface (or long Liebig) condenser and distil slowly (1-2 drops per second) until about half of the liquid has passed over. Separate the lower alkyl bromide layer (70 g.), and redistil the aqueous layer when a further 7 g. of the crude bromide will be obtained (1). Shake the crude bromide in a separatory funnel successively with an equal volume of concentrated hydrochloric acid (2), water, 5 per cent, sodium bicarbonate solution, and water, and dry with anhydrous calcium chloride. Distil from a 100 ml. flask the isopropyl bromide passes over constantly at 59°. The yield is 66 g. 

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. 

Conduct the preparation in the fume cupboard. Dissolve 250 g. of redistilled chloroacetic acid (Section 111,125) in 350 ml. of water contained in a 2 -5 litre round-bottomed flask. Warm the solution to about 50°, neutralise it by the cautious addition of 145 g. of anhydrous sodium carbonate in small portions cool the resulting solution to the laboratory temperature. Dissolve 150 g. of sodium cyanide powder (97-98 per cent. NaCN) in 375 ml. of water at 50-55°, cool to room temperature and add it to the sodium chloroacetate solution mix the solutions rapidly and cool in running water to prevent an appreciable rise in temperature. When all the sodium cyanide solution has been introduced, allow the temperature to rise when it reaches 95°, add 100 ml. of ice water and repeat the addition, if necessary, until the temperature no longer rises (1). Heat the solution on a water bath for an hour in order to complete the reaction. Cool the solution again to room temperature and slowly dis solve 120 g. of solid sodium hydroxide in it. Heat the solution on a water bath for 4 hours. Evolution of ammonia commences at 60-70° and becomes more vigorous as the temperature rises (2). Slowly add a solution of 300 g. of anhydrous calcium chloride in 900 ml. of water at 40° to the hot sodium malonate solution mix the solutions well after each addition. Allow the mixture to stand for 24 hours in order to convert the initial cheese-Uke precipitate of calcium malonate into a coarsely crystalline form. Decant the supernatant solution and wash the solid by decantation four times with 250 ml. portions of cold water. Filter at the pump. 

A good 3ueld of 5-iodo-2-aminotoluene may be obtained by intimately mixing o-toluidine hydrochloride, iodine and calcium carbonate, and then adding water to the mixture. The liberated hydriodic acid reacts at once with the Calcium carbonate and the lij driodide of the base is not formed. 

Thionyl chloride method. Mix 100 g. of pure p-nitrobenzoic acid and 125 g. (77 ml.) (1) of redistilled thionyl chloride in a 500 ml. round-bottomed flask. Fit the flask with a double surface reflux condenser carrying a calcium chloride (or cottou wool) guard tube and connect the latter to an absorption device e.g.. Fig. II, 8, c). Heat the flask on a... 

Place 45 g. of benzamide (Section IV, 188) and 80 g. of phosphorus pentoxide in a 250 ml. Claisen flask (for exact experimeutal details on the handling and weighing out of phosphoric oxide, see under Acetamide, Section 111,111). Mix well. Arrange for distillation (Fig.//, 29, 1 or Fig. II, 20, 1) under reduced pressure use a water pump with an air leak in the system so that a pressure of about 100 mm. is attained. Heat the flask with a free flame until no more liquid distils the nitrile will pass over at 126-130°/100 mm. Wash the distillate with a little sodium carbonate solution, then with water, and dry over anhydrous calcium chloride or magnesium sulphate. Distil under normal pressure (Fig. II, 13, 2 or II, 13, 6) from a 50 ml. flask the benzonitrile passes over as a colourless liquid at 188-189° (compare Section IV,66). The yield is 28 g. 

Mix intimately in a mortar 100 g. of sodium laevulinate, 250 g. of phosphorus sulphide (1) and 50 g. of clean dry sand. Place the mixture in a flask fitted with a condenser for distillation and a receiver (2). Heat the flask with a free flame until the reaction commences, and then remove the flame. When the reaction subsides, continue the heating until distillation ceases. Wash the distillate with 10 per cent, sodium hydroxide solution to remove acidic by-products and steam distil. Separate the crude 2-methyltliiophene from the steam distillate, dry over anhydrous calcium sulphate, and distil from a little sodium. Collect the pure compound at 113° the yield is 30 g. 

Preparation of palladium - calcium carbonate catalyst. Prepare 60 g. of precipitated calcium carbonate by mixing hot solutions of the appropriate quantities of A.R. calcium chloride and A.R. sodium carbonate. Suspend the calcium carbonate in water and add a solution containing 1 g. of palladium chloride. Warm the suspension until all the palladium is precipitated as the hydroxide upon the calcium carbonate, i.e., until the supernatant liquid is colourless. Wash several times with... 

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