Iodide temperature

Figure 3.46. Ionic components of charge in the double layer on silver iodide. Temperature 25 C.

Ammonium chloride, NH4CI, crystallizes in a CsCl lattice up to a temperature of 174-3 0 and above that temperature, in the NaCl lattice. Similar behaviour is observed with ammonium bromide (temperature of transformation 137-8 C) and ammonium iodide (temperature of transformation — /I7-6 C). The interionic distances in the CsGl lattice are actually found to be approximately 3 per cent greater than in the NaGl... 

The swelling of gels is markedly affected by the presence of electrolytes, this effect being a minimum at the isoelectric point of the material. In general, sulphates, tartrates, etc. inhibit swelling, while iodides and thiocyanates promote the swelling. Thus gelatine disperses completely in iodide solution even at low temperatures. 

Iodine is a dark-coloured solid which has a glittering crystalline appearance. It is easily sublimed to form a bluish vapour in vacuo. but in air, the vapour is brownish-violet. Since it has a small vapour pressure at ordinary temperatures, iodine slowly sublimes if left in an open vessel for the same reason, iodine is best weighed in a stoppered bottle containing some potassium iodide solution, in which the iodine dissolves to form potassium tri-iodide. The vapour of iodine is composed of I2 molecules up to about 1000 K above this temperature, dissociation into iodine atoms becomes appreciable. 

Addition of aqueous cyanide ion to a copper(II) solution gives a brown precipitate of copper(II) cyanide, soluble in excess cyanide to give the tetracyanocuprate(II) complex [Cu(CN)4] . However, copper(II) cyanide rapidly decomposes at room temperature, to give copper(I) cyanide and cyanogen(CN)2 (cf. the similar decomposition of copper(II) iodide, below) excess cyanide then gives the tetracyanocuprate(I) [Cu(CN)4] . 

Place 0 5 ml. of acetone, 20 ml. of 10% aqueous potassium iodide solution and 8 ml. of 10% aqueous sodium hydroxide solution in a 50 ml. conical flask, and then add 20 ml. of a freshly prepared molar solution of sodium hypochlorite. Well mix the contents of the flask, when the yellow iodoform will begin to separate almost immediately allow the mixture to stand at room temperature for 10 minutes, and then filter at the pump, wash with cold w ater, and drain thoroughly. Yield of Crude material, 1 4 g. Recrystallise the crude iodoform from methylated spirit. For this purpose, place the crude material in a 50 ml. round-bottomed flask fitted with a reflux water-condenser, add a small quantity of methylated spirit, and heat to boiling on a water-bath then add more methylated spirit cautiously down the condenser until all the iodoform has dissolved. Filter the hot solution through a fluted filter-paper directly into a small beaker or conical flask, and then cool in ice-water. The iodoform rapidly crystallises. Filter at the pump, drain thoroughly and dry. 

In the reaction described below triethyl phosphite (p. 308) is heated with ethyl iodide to give diethyl ethylphosphonate. Although theoretically a very small amount of ethyl iodide would suffice, it is advantageous to use more than the minimum amount so as to reduce the temperature of the boiling reaction-mixture. 

Some less reactive tertiary amines can be mixed with an excess of methyl toluene-/)-sulphonate, m.p. 28 , and the mixture (without a solvent) heated to a much higher temperature. The mixture is allowed to cool, but before solidification occurs, it is thoroughly stirred with ether to extract unused sulphonate, and the insoluble quaternary metho-toluene-/)-sulphonate may then crystallise. If ciystallisation does not occur, dissolve this residue in ethanol and treat one portion with ethanolic picric acid (to precipitate the methopicrate) and another portion with cold concentrated ethanolic sodium iodide (to precipitate the methiodide). (M.ps. of the siilphon.ates, pp. 553 -554.)... 

In a 500 ml. three-necked flask, equipped with a thermometer, a sealed Hershberg stirrer and a reflux condenser, place 32-5 g. of phosphoric oxide and add 115-5 g. (67-5 ml.) of 85 per cent, orthophosphoric acid (1). When the stirred mixture has cooled to room temperature, introduce 166 g. of potassium iodide and 22-5 g. of redistilled 1 4-butanediol (b.p. 228-230° or 133-135°/18 mm.). Heat the mixture with stirring at 100-120° for 4 hours. Cool the stirred mixture to room temperature and add 75 ml. of water and 125 ml. of ether. Separate the ethereal layer, decolourise it by shaking with 25 ml. of 10 per cent, sodium thiosulphate solution, wash with 100 ml. of cold, saturated sodium chloride solution, and dry with anhydrous magnesium sulphate. Remove the ether by flash distillation (Section 11,13 compare Fig. II, 13, 4) on a steam bath and distil the residue from a Claisen flask with fractionating side arm under diminished pressure. Collect the 1 4-diiodobutane at 110°/6 mm. the yield is 65 g. 

In a 1-litre three-necked flask, fitted with a mechanical stirrer, reflux condenser and a thermometer, place 200 g. of iodoform and half of a sodium arsenite solution, prepared from 54-5 g. of A.R. arsenious oxide, 107 g. of A.R. sodium hydroxide and 520 ml. of water. Start the stirrer and heat the flask until the thermometer reads 60-65° maintain the mixture at this temperature during the whole reaction (1). Run in the remainder of the sodium arsenite solution during the course of 15 minutes, and keep the reaction mixture at 60-65° for 1 hour in order to complete the reaction. AUow to cool to about 40-45° (2) and filter with suction from the small amount of solid impurities. Separate the lower layer from the filtrate, dry it with anhydrous calcium chloride, and distil the crude methylene iodide (131 g. this crude product is satisfactory for most purposes) under diminished pressure. Practically all passes over as a light straw-coloured (sometimes brown) liquid at 80°/25 mm. it melts at 6°. Some of the colour may be removed by shaking with silver powder. The small dark residue in the flask solidifies on cooling. 

If the temperature is allowed to rise, the yield is slightly diminished owing to the formation of a little methyl iodide. 

If the temperature falls below 40°, a precipitate of sodium arsenate will gradiially separate and this will tend to produce an emulsion of the methylene iodide, thus rendering filtration and separation difficult. 

The experimental conditions necessary for the preparation of a solution of a diazonium salt, diazotisation of a primary amine, are as follows. The amine is dissolved in a suitable volume of water containing 2 5-3 equivalents of hydrochloric acid (or of sulphuric acid) by the application of heat if necessary, and the solution is cooled in ice when the amine hydrochloride (or sulphate) usually crystallises. The temperature is maintained at 0-5°, an aqueous solution of sodium nitrite is added portion-wise until, after allowing 3-4 minutes for reaction, the solution gives an immediate positive test for excess of nitrous acid with an external indicator—moist potassium iodide - starch paper f ... 

Dissolve 20 g, (19 -6 ml.) of anihne in a mixture of 55 ml. of concentrated hydrochloric acid (1) and 55 ml. of water contained in a 350 ml, conical flask. Place a thermometer in the solution and immerse the flask in a bath of crushed ice (2) cool until the temperature of the stirred solution falls below 5°, Dissolve 16 g. of sodium nitrite in 75 ml. of water and chUl the solution by immersion in the ice bath add the sodium nitrite solution (3) in small volumes (2-3 ml. at a time) to the cold anihne hydrochloride solution, and keep the latter weh stirred with the thermometer. Heat is evolved by the reaction. The temperature should not be allowed to rise above 10° (add a few grams of ice to the reaction mixture if necessary) otherwise appreciable decomposition of the diazonium compound and of nitrous acid wih occur. Add the last 5 per cent, of the sodium nitrite solution more slowly (say, about 1 ml. at a time) and, after stirring for 3-4 minutes, test a drop of the solution diluted with 3-4 drops of water with potassium iodide - starch paper (4) if no immediate blue colour... 

Dissolve 36 g. of p-toluidine in 85 ml. of concentrated hydrochloric acid and 85 ml. of water contained in a 750 ml. conical flask or beaker. Cool the mixture to 0° in an ice-salt bath with vigorous stirring or shaking and the addition of a httle crushed ice. The salt, p-toluidine hydrochloride, will separate as a finely-divided crystalline precipitate. Add during 10-15 minutes a solution of 24 g. of sodium nitrite in 50 ml. of water (1) shake or stir the solution well during the diazotisation, and keep the mixture at a temperature of 0-5° by the addition of a httle crushed ice from time to time. The hydrochloride wUl dissolve as the very soluble diazonium salt is formed when ah the nitrite solution has been introduced, the solution should contain a trace of free nitrous acid. Test with potassium iodide - starch paper (see Section IV,60). 

Dissolve 46-5 g. (45-5 ml.) of aniUne in a mixture of 126 ml. of concentrated hydrochloric acid and 126 ml. of water contained in a 1-htre beaker. Cool to 0-5° in a bath of ice and salt, and add a solution of 36-5 g. of sodium nitrite in 75 ml. of water in small portions stir vigorously with a thermometer (1) and maintain the temperature below 10°, but preferably at about 5° by the addition of a httle crushed ice if necessary. The diazotisation is complete when a drop of the solution diluted with 3-4 drops of water gives an immediate blue colouration with potassium iodide - starch paper the test should be performed 3-4 minutes after the last addition of the nitrite solution. Prepare a solution of 76 g. of sodium fluoborate (2) in 150 ml. of water, cool, and add the chilled solution slowly to the diazonium salt solution the latter must be kept well stirred (1) and the temperature controlled so that it is below 10°. Allow to stand for 10 minutes with frequent stirring. Filter... 

Dissolve 34 g. of o-nitroaniline in a warm mixture of 63 ml. of concentrated hydrochloric acid and 63 ml. of water contained in a 600 ml. beaker. Place the beaker in an ice - salt bath, and cool to 0-5° whilst stirring mechanically the o-nitroaniline hydrochloride will separate in a finely-divided crystalline form. Add a cold solution of 18 g. of sodium nitrite in 40 ml. of water slowly and with stirring to an end point with potassium iodide - starch paper do not allow the temperature to rise above 5-7 . Introduce, whilst stirring vigorously, a solution of 40 g. of sodium borofluoride in 80 ml. of water. Stir for a further 10 minutes, and filter the solid diazonium fluoborate with suction on a sintered glass funnel. Wash it immediately once with 25 ml. of cold 5 per cent, sodium borofluoride solution, then twice with 15 ml. portions of rectified (or methylated) spirit and several times with ether in each washing stir... 

Add 101 g. (55 ml.) of concentrated sulphuric acid cautiously to 75 ml. of water contained in a 1 htre beaker, and introduce 35 g. of finely-powdered wi-nitroaniline (Section IV,44). Add 100-150 g. of finely-crushed ice and stir until the m-nitroaniUne has been converted into the sulphate and a homogeneous paste results. Cool to 0-5° by immersion of the beaker in a freezing mixture, stir mechanically, and add a cold solution of 18 g. of sodium nitrite in 40 ml. of water over a period of 10 minutes until a permanent colour is immediately given to potassium iodide - starch paper do not allow the temperature to rise above 5-7° during the diazotisation. Continue the stirring for 5-10 minutes and allow to stand for 5 minutes some m-nitrophenjddiazonium sulphate may separate. Decant the supernatant Uquid from the solid as far as possible. 

Place 130 ml. of concentrated hj drochloric acid in a 1 - 5 litre round-bottomed flask, equipped ith a mechanical stirrer and immersed in a freezing mixture of ice and salt. Start the stirrer and, when the temperature has fallen to about 0°, add 60 g. of finely-crushed ice (1), run in 47 5 g. (46 5 ml.) of pure aniline during about 5 minutes, and then add another 60 g. of crushed ice. Dissolve 35 g. of sodium nitrite in 75 ml. of water, cool to 0-3°, and run in the cold solution from a separatory funnel, the stem of which reaches nearly to the bottom of the flask. During the addition of the nitrite solution (ca. 20 minutes), stir vigorously and keep the temperature as near 0° as possible by the frequent addition of crushed ice. There should be a slight excess of nitrous acid (potassium iodide-starch paper test) at the end of 10 minutes after the last portion of nitrite is added. 

Prepare a solution containing about 100 g, of potassium hypochlorite from commercial calcium hypochlorite ( H.T.H. ) as detailed under -Dimethylacrylic Acid, Section 111,142, Note 1, and place it in a 1500 ml. three-necked flask provided with a thermometer, a mechanical stirrer and a reflux condenser. Warm the solution to 55° and add through the condenser 85 g, of p-acetonaphthalene (methyl p-naphthyl ketone) (1). Stir the mixture vigorously and, after the exothermic reaction commences, maintain the temperature at 60-70° by frequent cooling in an ice bath until the temperature no longer tends to rise (ca. 30 minutes). Stir the mixture for a further 30 minutes, and destroy the excess of hypochlorite completely by adding a solution of 25 g. of sodium bisulphite in 100 ml. of water make sure that no hypochlorite remains by testing the solution with acidified potassium iodide solution. Cool the solution, transfer the reaction mixture to a 2-litre beaker and cautiously acidify with 100 ml. of concentrated hydrochloric acid. Filter the crude acid at the pump. 

Ethyl phenylethylmalonate. In a dry 500 ml. round-bottomed flask, fitted with a reflux condenser and guard tube, prepare a solution of sodium ethoxide from 7 0 g. of clean sodium and 150 ml. of super dry ethyl alcohol in the usual manner add 1 5 ml. of pure ethyl acetate (dried over anhydrous calcium sulphate) to the solution at 60° and maintain this temperature for 30 minutes. Meanwhile equip a 1 litre threenecked flask with a dropping funnel, a mercury-sealed mechanical stirrer and a double surface reflux condenser the apparatus must be perfectly dry and guard tubes should be inserted in the funnel and condenser respectively. Place a mixture of 74 g. of ethyl phenylmalonate and 60 g. of ethyl iodide in the flask. Heat the apparatus in a bath at 80° and add the sodium ethoxide solution, with stirring, at such a rate that a drop of the reaction mixture when mixed with a drop of phenolphthalein indieator is never more than faintly pink. The addition occupies 2-2 -5 hoius continue the stirring for a fiuther 1 hour at 80°. Allow the flask to cool, equip it for distillation under reduced pressure (water pump) and distil off the alcohol. Add 100 ml. of water to the residue in the flask and extract the ester with three 100 ml. portions of benzene. Dry the combined extracts with anhydrous magnesium sulphate, distil off the benzene at atmospheric pressure and the residue under diminished pressure. C ollect the ethyl phenylethylmalonate at 159-160°/8 mm. The yield is 72 g. 

Apply the test to compounds which contain chlorine or bromine. If the compound is a solid, dissolve 0 1 g. in the minimum volume of pure, dry acetone. To 1 ml. of the sodium iodide acetone reagent add 2 drops of the compound (if a hquid) or the acetone solution (if a sohd). Shake and allow to stand at room temperature for 3 minutes. Note whether a precipitate is formed and also whether the solution acquires a reddish-brown colour (liberation of iodine). If no change takes place at rocrm temperature, place the test-tube in a beaker of water at 50°. After 5 minutes, cool to room temperature, and observe whether a reaction has occurred. 

Iodine is a bluish-black, lustrous solid, volatizing at ordinary temperatures into a blue-violet gas with an irritating odor it forms compounds with many elements, but is less active than the other halogens, which displace it from iodides. Iodine exhibits some metallic-like properties. It dissolves readily in chloroform, carbon tetrachloride, or carbon disulfide to form beautiful purple solutions. It is only slightly soluble in water. 

The reaction product is cooled to room temperature, is washed with 10 ml of H2O to the purpose of removing lithium iodide and is then dehydrated over NaiS04. 3.57 g is obtained of dimethoxy-phenylacetone (III), as determined by gas-chromatographic analysis with an inner standard of 4,4 -dimethoxybeniophenone. The yield of ketone (III) relative to the olefin ( ) used as the starting material is of 87.1%. 

A solution of 0.60 mol of ethyllithium (note 1) in about 400 ml of diethyl ether (see Chapter II, Exp. 1) was added in 30 min to a mixture of 0.25 mol of 1,4-diethoxy-2-butyne (see Chapter VIII-6, Exp. 8) and 100 ml of dry diethyl ether. The temperature of the reaction mixture was kept between -40 and -45°C. Fifteen minutes after the addition had been completed, 0.5 mol of methyl iodide was added at -40 C, then 100 ml of dry HMPT (for the purification see ref. 1) were added dropwise in 15 min while keeping the temperature at about -40°C. Thirty minutes after this addition the cooling bath was removed, the temperature was allowed to rise and stirring was continued for 3 h. The mixture was... 

A solution of 92 g of dry sodium iodide in 350 ml of 100% ethanol (note 1) was heated to about 70°C. Freshly distilled propargyl bromide (note 2) (0.50 mol) was added in 10 min. After heating for 20 min at 70-75°C the white suspension was cooled to room temperature and 500 ml of water were added, then the product was... 

A mixture of E and Z forms is obtained by the reaction of the fZ)-alkenyl bromide 33. Z to E isomerization takes place. However, the reaction is remarkably accelerated by using K2CO3 instead of KHC03[17] and BU4NCI in DMF, and the reaction of the (Z)-iodide 34 proceeds rapidly at room temperature without isomerization[37]. 

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