Ammonium bromide : crystal

Ammonium chloride [12125-02-9] NH Q, ammonium bromide [12124-97-9] NH Br, and ammonium iodide [12027-06-4] NH I, are crystalline, ionic compounds of formula wts 53.49, 97.94, and 144.94, respectively. Their densities d systematically foUow the increase in formula weight 1.53, 2.40, and 2.52. AH three exist in two crystal modifications (10) the chloride, bromide, and iodide have the CsQ stmcture below temperatures of 184.5, 137.8, and — 17.6°C, respectively each reversibly transforms to the NaQ. stmcture at higher temperatures. 

For ammonium bromide, another method involving reaction of an aqueous bromine solution and Hon filings has been used. The solution of ferrous and ferric bromide thus formed then reacts with ammonia to precipitate hydrated oxides of Hon. Ammonium bromide can be recovered by crystallization from the concentrated Hquor. 

The lustrous black crystals of trirhenium nonabromide are not rapidly degraded on exposure to the atmosphere the crystals can be stored over desiccants for months without evidence of decomposition. The bromide dissolves fairly slowly and sparingly in ether and acetone. In methanol, the bromide gives yellow-orange solutions, but it is solvolyzed within minutes. Similarly, the bromide dissolves in water at room temperature to yield a violet solution which darkens rapidly, yielding a black precipitate, presumably the hydrated dioxide.9 Contrary to published work,10 the bromide does dissolve in ammonia with solvolysis, as is evidenced by lines attributable to ammonium bromide in x-ray diffraction data of the solid residue recovered from liquid ammonia solutions.11 Trirhenium nonabromide reacts with Lewis bases such as phosphines and amines to form a series of complexes of the type (base) 3Re3Br9.6... 

The addition of bromine to quaternary ammonium bromides to provide the tribromides is most easily achieved in a reaction column with the solid while a stream of air carries the required amount of bromine (Scheme 11). Thus, in the case of tetrabutylammonium bromide (TBAB), a sharp yellow reaction front is obtained while bromine is quantitatively added and the pure bromi-nation agent TBABrg is obtained. Small runs can be quantitatively performed with 0.5 bar bromine vapor and the unground crystals of TBAB [28]. Equally simple is the gas-solid addition of chlorine to triphenylphosphane to give triphenylphosphane dichloride [28]. 

The crystals of ammonium bromide agree in all respects with those of ammonium chloride. They belong to the cubic system, and the crystals obtained from aq. 

The mother liquor saved from the precipitate should be evaporated to recover the ammonium chloride which it contains. If it is not clear, it should be filtered, and hydrochloric acid should then be added to neutralize the ammonia and decompose the ammonium carbonate. Having made the solution decidedly acid, evaporate to crystallization, securing a second crop of crystals if the first crop is small. The final mother liquors should be rejected, as they will contain ammonium bromide. 

With the alkali bromides and alkyl ammonium bromides selenium tetrabromide can form crystalline additive compounds of the type MaSeBr6, termed selenibromides. Indeed, by the action of bromine on finely divided selenium in the presence of concentrated hydrobromic acid, a solution is obtained 4 which gradually deposits deep red crystals of hydrogen selenibromide, HaSeBr6. The solution of this body in hydrobromic acid on dilution with water undergoes decomposition with liberation of colloidal selenium. Two reactions probably occur concurrently ... 

Ammonium Bromide Lactose Base Granules Pharmaceutical Crystals Liver Residue Weed Killer... 

Thirty grams of the complex chloride are dissolved in 100ml of water at 65cC and 45g of sodium or ammonium bromide are stirred in, The product precipitates immediately and is recovered by cooling in ice to complete the crystallization, then filtering by suction. 

In a i-l. round-bottom flask is placed 760 g. of concentrated ammonium hydroxide (sp. gr. 0.9) and to this is slowly added 150 g. of a-bromocaproic acid (Note 1). The flask is well stoppered and allowed to stand in a warm place (50-55°) for twenty to thirty hours. The amino acid separates and is filtered off with suction and washed with methyl alcohol (Note 2). This crop of crystals weighs 51-56 g. The aqueous filtrate is evaporated nearly to dryness on a steam bath and then treated with about 250 cc. of methyl alcohol. This precipitates a second crop of amino acid contaminated with ammonium bromide. On washing with methyl alcohol and recrystallizing from water, there is obtained 10—15 g. more of pure product. The total yield is 63-68 g. (62-67 per cent of the theoretical amount). 

The residue consists of a syrup (largely glycine hydrobromide) mixed with crystals of ammonium bromide. It has a strong odor of formaldehyde. 

The filtrate is concentrated to dryness in vacuo and the residue is taken up in 25 cc of ethanol. The residual ammonium bromide is removed by filtration and to the filtrate there is added sufficient diethylamine to change the pH to 6.4. The mixture is warmed to 60°C and then cooled to room temperature. It is then allowed to stand overnight to effect complete crystallization. It is then cooled to 0°C and the product is isolated by filtration, washed with methanol and air dried. The product (a-hydrazino-a-methyl-p-(3,4-dihydroxyphenyl)-propionic acid) is recrystallized once from water using a proportion of 15 cc water per gram of product. 

Dextro Form. To the filtrate A immediately after the removal of the levo diastereoisomer J is added 2 g. of ammonium bromide. The sides of the flask are scratched with a glass rod and the mixture allowed to crystallize at 20 to 25° for 5 minutes. The impure d-bromide is collected and washed once on the Buchner with 10 ml. of ice water. From the filtrate B dZ-[Co(en)2(N02)2]I can be recovered by the addition of sodium or potassium iodide, 5 g. being a sufficient amount (yield approximately 40%). The impure... 

Ammonium Pentabromrhodite, (NHJjRhBrg, is conveniently prepared by precipitating potassium bromide from a solution of potassium pentabromrhodite by passing in hydrogen bromide. To the filtrate dilute ammonium bromide solution 5 is added. On standing for several days the salt separates out in blackish green crystals.6... 

In concentrated aqueous solution ammonium bromide is converted by electrolysis or the action of bromine into ammonium tribromide, NH4Br,Br2,.16 This substance is unstable, and forms large columnar crystals with a colour similar to that of potassium dichromate. Ammonium bromide combines with ammonia to form complex de-... 

The ammonium bromide, potassium iodide, and sodium acetate were British Drug Houses Analar analytical reagent grade. The potassium acetate was Baker Analyzed crystal reagent grade from J. T. Baker Chemical Co. Owing to the extreme hygroscopicity of some of these salts, they all were dried for at least 72 hours at 120° C immediately prior to each series of experiments. The dried salts then were stored under vacuum over phosphoric pentoxide between each experimental measurement. 

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