Ammonium chloride, solution preparation

A solution of a-lithiomethoxyallene was prepared from nethoxyal lene and 0.20 mol of ethyllithiurn (note 1) in about 200 ml of diethyl ether (see Chapter II, Exp. 15). The solution was cooled to -50°C and 0.20 mol of ethylene oxide was added immediately. The cooling bath was removed temporarily and the temperature was allowed to rise to -15 c and was kept at this level for 2.5 h. The mixture was then poured into 200 ml of saturated ammonium chloride solution, to which a few millilitres of aqueous ammonia had been added (note 2). After shaking the layers were separated. The aqueous layer was extracted six times with small portions of diethyl ether. The combined ethereal solutions were dried over sodium sulfate and subsequently concentrated in a water-pump vacuum. Distillation of the... 

After the flask has been cooled by immersion in ice water, 44 g- (o-5 mole) of dry ethyl acetate (Note i) in an equal volume of ether is added over a period of twelve minutes. The cooling bath is removed and stirring is continued for ten minutes. When the reaction flask has again been cooled by the ice-water bath, a previously prepared ammonium chloride solution (Note 2) is added, very slowly at first, over a period of ten minutes, during which a pasty solid separates. 

The ammonium chloride solution is prepared by dissolving 50 g. of ammonium chloride in 150 cc. of water at 25-30°. The literature recommends the use of 30 per cent sulfuric acid for decomposing the magnesium compound when this is used, the yield drops to 50 -55 per cent, probably owing to the ready polymerization of the hydrocarbon in the presence of mineral acids. 

A solution of 6.3 g (0.9 moles) ethoxyacetylene in 50 ml ether is added dropwise during 30 min to a Grignard reagent prepared from 2.18 g (90 mg-atoms) magnesium and 9.81 g (90 mmoles) ethyl bromide. The reaction mixture is stirred for 1 hr at room temperature and then a solution of 3 g (9 mmoles) 3) -acetoxyandrost-5-en-I7-one in 50 ml dry ether is added dropwise. The mixture is refluxed for 1 hr and after cooling to 0° poured into 100 ml of an aqueous ammonium chloride solution. The aqueous solution is extracted with ether, and the organic extract is washed with ammonium chloride solution and water, dried, and evaporated. The residue is chromatographed on 130 g alumina (activity III). Elution with petroleum ether-benzene (1 1) yields, after crystallization from acetone-hexane, 1.27 g (35%) 3j5-acetoxy-17a-ethoxyethynylandrost-5-en-17) -ol mp 138-139° Ho -122°. 

Preparation of 4-aza-S-(N-methyl-4-piperidyll-10,11-dihydro-SH-dibenzo[a,d]cycloheptene-S-ol Add 17.4 g of N-methyl-4-chloropiperidine to a stirred mixture containing 3.2 g of magnesium, 20 ml of anhydrous tetrahydrofuran, 1 ml of ethyl bromide and a crystal of iodine. Reflux for two hours, cool to 30°-35°C and add a solution of 13 g of 4-aza-10,11 -dihydro-5H-dibenzo[a,d] cycloheptene-5-one in 25 ml of tetrahydrofuran. Stir for five hours, remove the solvent by distillation in vacuo and add 250 ml of ether. Add 100 ml of 10% ammonium chloride solution and extract the mixture with chloroform. Concentrate the chloroform solution to a residue and recrystallize from isopropyl ether obtaining 20 g of the carbinol,... 

To a solution of thienyl magnesium bromide prepared from 21.4 g of magnesium and 144 g of 2-bromothiophene are added 39.B g of ethyl 4-dimethylaminocyclohexylcarboxylate. The mixture is ailowed to warm to room temperature and stirred for an additional six hours. The reaction mixture is then decomposed with dilute ammonium chloride solution and extracted with ether. The combined ether extracts are extracted thoroughiy with 10% hydrochloric acid and the acid solution made alkaline with ammonium hydroxide. The aqueous solution is extracted with chloroform which is then washed with water, dried and evaporated to a residue in vacuo. Recrystallization of the residue from hexane yields Oi.O -dithienyl-4-dimethyl-aminocyclohexyl carbinol, melting point 156°C to 157°C after recrystallization from benzene. 

Procedure (b). Prepare the indicator by dissolving 0.05 g bromopyrogallol red in 100 mL of 50 per cent ethanol, and a buffer solution by mixing 100 mL of 1M ammonium chloride solution with 100 mL of 1M aqueous ammonia solution. 

Procedure. Prepare the murexide indicator as described in Section 10.57(a), and an ammonium chloride solution (1M) by dissolving 26.75 g ammonium chloride in de-ionised water in a 500 mL graduated flask. 

Prepare a standard ammonium chloride solution as follows. Dissolve 3.141 g ammonium chloride, dried at 100 °C, in ammonia-free water and dilute to 1 L with the same water. This stock solution is too concentrated for most purposes. A standard solution is made by diluting lOmL of this solution to 1 L with ammonia-free water 1 mL contains 0.01 mg of NH3. 

If necessary, dilute the sample to give an ammonia concentration of 1 mg L 1 and fill a 50 mL Nessler tube to the mark. Prepare a series of Nessler tubes containing the following volumes of standard ammonium chloride solution diluted to 50 mL 1.0,2.0,3.0,4.0,5.0, and 6.0 mL. The standards contain 0.01 mg NH3 for each mL of the standard solution. Add 1 mL of Nessler s reagent to each tube, allow to stand for 10 minutes, and compare the unknown with the standards in a Nessler stand (Section 17.4) or in a BDH Nesslerimeter. This will give an approximate figure which will enable another series of standards to be prepared and more accurate results to be obtained. 

A mixture of p-chloroanisole (0.5 mol) and PhLi (0.5 mol, prepared from PhBr and Li in ether) in ether (600 ml) was stirred at ambient temperature for 50 h. A solution of TMSCI (0.5 mol) in ether (50 ml) was added with stirring, which was continued for a further 24 h. The mixture was poured into saturated ammonium chloride solution, the layers were separated, and the ethereal layer was dried. Concentration and fractional distillation gave 4-chloro-2-trimethylsilylanisole, b.p. 84°C/2mmHg. which crystallized in the receiver. Three crystallizations from ethanol gave the pure silane (0.3mol, 60%). m.p. 51-51.5°C. 

To (E)-stilbcnc oxide (25 mmol) in THF (35 ml) was added freshly prepared dimethylphenylsilyl lithium (25.35 mmol, 1.3 m in THF) dropwise at ambient temperature. The solution was stirred at ambient temperature for 4h, and then poured into saturated ammonium chloride solution (15ml), diluted with ether, and the separated organic layer was dried and concentrated. The crude product (97 3 (Z) (E), g.I.c.) was purified by chromatography on silica gel to give (Z)-stilbene (18.75 mmol, 75%). 

Worked Example 6.12 We need to prepare a buffer of pH 9.8 by mixing solutions of ammonia and ammonium chloride solution. What volumes of each are required Take the Ka of the ammonium ion as 6 x 10 l0. Assume the two solutions have the same concentration before mixing. 

Hydroxylamine is unstable as a free base. It is prepared from hydroxylamine hydrochloride, NH20H HC1, which is obtained by electrolytic reduction of ammonium chloride solution. The hydrochloride undergoes alkaline decomposition to hydroxylamine, which is collected by vacuum distdlation. 

Ammonium Tetranitrito - diammino - cobaltate, [Co(XH3)2 (N02)4]NH4, is prepared from cobaltous chloride by mixing an aqueous solution of the salt with aqueous ammonium-chloride solution, sodium nitrite, and ammonia, and oxidising the mixture by passing air through it for several hours. The solution is allowed to stand in air for some days, when crystals gradually separate. These are collected, washed, and reerystallised from water.3 The substance crystallises in brown rhombic prisms. It is decomposed on treatment with potassium hydroxide with evolution of ammonia, and a cold solution reacts with ammonia in presence of ammonium salts, with formation of flavo-dinitro double salts, of which [Co(NH3)4(N02)2][Co(NH3)2(N02)4] is typical. Oxalic acid transforms it into the oxalato-dinitrito-diammino-salt, [Co(NH3)2(N02)2(C204)]NH4. 

Assemble an arrangement as shown in Fig. 76 and check its tightness. Spill 1-2 g of triturated sodium nitrite into the test tube, pour in dropwise 2-3 ml of a concentrated ammonium chloride solution, and carefully (why ) heat the mixture. Collect the evolving gas and see whether it supports combustion. Write the equation of the reaction of nitrogen preparation. 

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