Separation hydroxylamines

Cyclohexanone oxime. Add 20 g. (21 ml.) of cyclohexanone to a solution of 17 g. of hydroxylamine hydrochloride in 40 ml. of water, and cool the mixture in ice-water. Add a solution of 13 g. of anhydrous sodium carbonate in 40 ml. of water slowly to the mixture, stirring the latter with a 100° thermometer, and maintaining the temperature of the mixture at 20-25° meanwhile. The oxime rapidly separates. Stir the complete mixture at intervals, and after 10 minutes filter the oxime at the pump, drain thoroughly and dry it in a (vacuum) desiccator. Yield of crude oxime, 20 g. Recrystallise from petroleum (b.p. 100-120 ) and dry over paraffin wax (p. 19). Yield of pure oxime, 16 g., m.p. 88°. 

Dissolve 5 g. of hydroxylamine hydrochloride in 10 ml. of water in a small conical flask and add a solution of 3 g. of sodium hydroxide in 10 ml. of water. Cool the solution in cold or ice water, and add 6 g. (7-6 ml.) of acetone slowly. Cool the flask, shake well, and leave overnight, during which time the oxime may crystallise out. If no crystals appear, cork the flask and shake vigorously when the acetoxime usually separates as colourless crystals. Filter the crystals at the pump, dry rapidly between filter paper (yield 2- 6 g.) and determine the m.p. (59°). Extract the filtrate with two 20 ml. portions of ether, and remove the solvent a further 0 - 5 g. of acetoxime (m.p. 60°) is obtained. Recrystallise from light petroleum, b.p. 40-60° CAUTION inflammable) to obtain the pure acetoxime, m.p. 60°. Acetoxime sublimes when left exposed to the air. 

Dissolve 2 5 g. of hydroxylamine hydrochloride and 4 g. of crystallised sodium acetate in 10 ml. of water in a small flask or in a test-tube. Warm the solution to about 40° and add 2 5 g. of cyclohexanone. Stopper the vessel securely with a cork and shake vigorously for a few minutes the oxime soon separates as a crystalline solid. Cool in ice, filter the crystals at the pump, and wash with a little cold water. RecrystaUise from light petroleum, b.p. 60-80°, and dry the crystals upon filter paper in the air. The yield of pure cycZohexanone oxime, m.p. 90°, is 2 -5 g. 

In a 250 ml. conical flask mix a solution of 14 g. of sodium hydroxide in 40 ml. of water and 21 g. (20 ml.) of pure benzaldehyde (Section IV,115). Add 15 g. of hydroxylamine hydrochloride in small portions, and shake the mixture continually (mechanical stirring may be employed with advantage). Some heat is developed and the benzaldehyde eventually disappears. Upon coohiig, a crystalline mass of the sodium derivative separates out. Add sufficient water to form a clear solution, and pass carbon dioxide into the solution until saturated. A colourless emulsion of the a or syn-aldoxime separates. Extract the oxime with ether, dry the extract over anhydrous magnesium or sodium sulphate, and remove the ether on a water bath. Distil the residue under diminished pressure (Fig. 11,20, 1). Collect the pure syn-benzaldoxime (a-benzald-oxime) at 122-124°/12 mm. this gradually solidifies on cooling in ice and melts at 35°. The yield is 12 g. 

Oximes (compare Section III,74,B). The following procedure has wide application. Dissolve 0-5 g. of hydroxylamine hydrochloride in 2 ml. of water, add 2 ml. of 10 per cent, sodium hydroxide solution and 0-2 g. of the aldehyde (or ketone). If the latter is insoluble, add just sufficient alcohol to the mixture to give a clear solution. Heat the mixture under reflux for 10-15 minutes, and then cool in ice. If crystals separate, filter these off, and recrystallise from alcohol, dilute alcohol, benzene or light petroleum (b.p. 60-80°). If no solid separates on cooling, dilute with 2-3 volumes of water, filter the precipitated sohd, and recrystallise. 

Veratronitrile, Dissolve 83 g. of veratraldehyde in 200 ml. of warm rectified spirit in a 1 litre bolt-head flask, and add a warm solution of 42 g. of hydroxylamine hydrochloride in 50 ml. of water. Mix thoroughly and run in a solution of 30 g. of sodium hydroxide in 40 ml. of water. Allow the mixture to stand for 2-5 hours, add 250 g. of crushed ice, and saturate the solution with carbon dioxide. The aldoxime separates as an oil allow the mixture to stand for 12-24 hours in an ice chest or refrigerator when the oil will sohdify. Filter off the crystalline aldoxime at the pump, wash well with cold water, and dry in the air upon filter paper. The yield of veratraldoxime is 88 g. 

Method 1. Dissolve 25 0 g. of salicylaldehyde (Section IV,122) in 215 ml. of 2N sodium hydroxide solution, add 12 05 g. of hydroxylamine hydrochloride, and warm the mixture for 30 minutes on a water bath. Acidify with acetic acid and cool in ice the salicylaldoxime separates as a congealed oil. Recrystalhae from chloroform - light petroleum (b.p. 40-60°). The yield of salicylaldoxime (colourless crystals, m.p. 57°) is 5 g. 

A number of substances, such as the most commonly used sulfur dioxide, can reduce selenous acid solution to an elemental selenium precipitate. This precipitation separates the selenium from most elements and serves as a basis for gravimetry. In a solution containing both selenous and teUurous acids, the selenium may be quantitatively separated from the latter by performing the reduction in a solution which is 8 to 9.5 W with respect to hydrochloric acid. When selenic acid may also be present, the addition of hydroxylamine hydrochloride is recommended along with the sulfur dioxide. A simple method for the separation and deterrnination of selenium(IV) and molybdenum(VI) in mixtures, based on selective precipitation with potassium thiocarbonate, has been developed (69). 

It was soon found that the reaction of unsymmetrtcal 1,3-diketones (290) or their derivatives with hydroxylamine results in both possible isomeric isoxazoles (291) and (292), a complication which not only reduces the yield of desired product but also often leads to separation problems, particularly when R and R are similar. However, the reaction does give one isomer, or predominantly one isomer, if the right combination of the CCC... 

Both 4,5-dimethylisoxazole and 3,4-dimethylisoxazole are formed on treatment of the sodium derivative of a-methylacetaldehyde with hydroxylamine hydrochloride. The two isomers can be separated by fractional distillation <62HC(17)1, p. 54). 4,5-Dialkylisoxazole or 3,4-dialkylisoxazole can be obtained as the sole reaction product from an appropriate nitrile iV-oxide and an appropriate vinyl acetate. 

The conversion of cyclohexanone to cyclohexanone oxime is brought about by the use of hydroxylamine sulphate. The sulphuric acid is neutralised with ammonia to ammonium sulphate and this is separated from the oxime. In the presence of oleum the oxime undergoes the process known as the Beckmann rearrangement to yield the crude caprolactam. After further neutralisation with ammonia the caprolactam and further ammonium sulphate are separated by solvent extraction (Figure 18.7). 

Hydroxypregna-5,16-dien-20-one Acetate Oxime 3j5-Hydroxy-pregna-5,16-dien-20-one acetate (30 g) is dissolved in 300 ml of anhydrous pyridine and 6.75 g of hydroxylamine hydrochloride is added. The mixture is stirred until solution is achieved, left in a tightly closed container at room temperature for 4 days and then poured into 1.5 liters of water. The flask is rinsed with water and the combined separated crystals are collected on a Buchner funnel, washed with water and dried to constant weight in an oven at 100°. Yield 30 g (96.5% of theory) mp 220-223°. 

The most characteristic derivative for the identification of fenchone is its oxime. Five grams of fenchone are dissolved in 80 c.c. of absolute alcohol and a solution of 11 grams of hydroxylamine hydrochloride in 11 C.C. of boiling water containing 6 grams of caustic potash, is added. After a time the oxime separates in the form of fine crystals which on recrystallisation from alcohol melt at 164° to 165° (active form) or 158° to 160° (inactive form). 

With hydroxylamine, menthenone yields a normal oxime, and an oxaminoxime. The latter body is not very volatile, and the oxime can be separated by steam distillation, and, when recrystaUised from alcohol, melts at 107° to 108°. The oxaminoxime melts at 164° to 165°. 

Ten grams of hydroxylamine hydrochloride are dissolved in 25 c.c. of water 10 grams of carbonate of potash, separately dissolved in 25 c.c. of water, are then added and the mixture filtered. With this solution 10 grams of the oil are thoroughly shaken for two hours at 15° to 18° C. The oil is then separated, dried with anhydrous sodium sulphate, and acetyl-ated with twice its volume of acetic. anhydride and one-fifth of its weight of anhydrous sodium acetate for two hours under a reflux condenser. The oil is washed, dried, and neutralised, and a weighed quantity (about 2 grams) saponified with alcoholic potash in the usual manner. 

As regards the use of hydroxylamine for the estimation of ketones, it was recommended by Kremers in 1901 for the estimation of oarvone in spearmint oil, the ketoxime being formed by treating the oil with hydroxylamine, and the remainder of the oil removed by steam distillation, the crystalline ketoxime which is left being separated, dried, and weighed. 

Acetylation.—Gitronellal may be quantitatively estimated by the ordinary acetylation process i when the aldehyde is quantitatively converted into isopulegyl acetate, which is then determined by saponification with potash in the ordinary way. Dupont and Labaume have attempted to base a method for the separation of geraniol from citronellal in citron-ella oils on the fact that the citronellal oxime formed by shaking with hydroxylamine solution at the ordinary temperature is not converted into an ester by subsequent acetylation, but into the nitrile of citronellic acid which is stable towards" alkali during the saponification process. 

A mixture of 202 g 2-amino-5-chlorobenzophenone, 190 g hydroxylamine hydrochloride, 500 cc pyridine and 1,200 cc alcohol was refluxed for 16 hours, then concentrated in vacuc to dryness. The residue was treated with a mixture of ether and water. The water was separated, the ether layer containing a considerable amount of precipitated reaction product was washed with some water and diluted with petroleum ether. The crystalline reaction product, 2-amino-5-chlorobenzophenone-0 -oxime, was filtered off. The product was recrystallized from a mixture of ether and petroleum ether forming colorless prisms, MP 164° to 167°C. 

In a 1,000 ml three-necked flask equipped with a stirrer, a dropping funnel and a silica gel guard pipe, 46.7 g hydroxylamine hydrochloride are dissolved cold in 480 ml methanol. Separately a solution of 56.1 g KOH in 280 ml methanol is prepared, heated to 30°C and edmixed, drop-wise under stirring to the hydroxylamine solution. All successive temperature increases dur-... 

Procedure The sodium hydroxide is dissolved in 200 ml water and the benzaldehyde is added. With continued stirring the hydroxylamine hydrochloride is added in portions. Some heat is developed and eventually the benzaldehyde dissolves. The solution is stirred for 15 minutes and then cooled in an ice-bath. A waxy, crystalline mass separates, and after further cooling it is collected by suction and dried in air. Yield is B6 to 149 grams. This crude material is suitable for step (B). 

The acid chloride reacts with the free hydroxylamine with considerable rapidity apparently without dissolving. The reaction is completed when a sample of the suspension shows to become clear on adding aqueous alkali. The crystalline pale-yellow mass of product Is separated by filtering, lavishly washed with water and dried in vacuum. The crude product yield is actually quantitative. The product is purified with excellent yields by repeatedly crystallizing from hot dioxane and washing with ether melting point 181°C to 182°C (dec.). 

Deacetylanisomycin (4) is synthesized using L-tartaric acid (1) as a precursor in 12% overall yield16. The key step is the diastereoselective addition of (4-methoxybenzyl)magnesium chloride to the C — N double bond of nitrone 2 at 0°C in the presence of 1 equivalent of ethylmagncsium-bromide diethyl ether complex in dichloromethane. This procedure affords a chromatograph-ically separable mixture of the hydroxylamines 3 a and 3 b in a diastereomeric ratio [(2R,35,4R)/ (25,35,47 )] 70 30 and 60% yield from 2. 

Methyl-2-quinoxalinecarbaldehyde 1,4-dioxide (235) and A-(2-chloroethyl)-hydroxylamine hydrochloride (236) gave the nitrone, 2-(2-chloroethylimino-methyl)-3-methylquinoxahne l,4,A(-trioxide (237) (NaHCOa, 95% EtOH, warm then 20°C, 1 h 70% after separation from a byproduct). ... 

Figure 9 A synthetic mixture of water-soluble carboxylic acids separated by anion-exchange chromatography. Column 0.3 cm x 300 cm Diaoion CA 08, 16-20 p (Mitsubishi Kasei Kogyo). Eluant 200 mM HC1. Detection reaction with Fe3-benzohy-droxamic acid-dicyclohexy carbodiimide-hydroxylamine perchlorate-triethyl amine with absorbance at 536 nm. Analytes (1) aspartate, (2) gluconate, (3) glucuronate, (4) pyroglutamate, (5) lactate, (6) acetate, (7) tartrate, (8) malate, (9) citrate, (10) succinate, (11) isocitrate, (12) w-butyrate, (13) a-ketoglutarate. (Reprinted with permission from Kasai, Y., Tanimura, T., and Tamura, Z., Anal. Chem., 49, 655, 1977. 1977 Analytical Chemistry).

The monovalent Co chemistry of amines is sparse. No structurally characterized example of low-valent Co complexed exclusively to amines is known. At low potentials and in non-aqueous solutions, Co1 amines have been identified electrochemically, but usually in the presence of co-ligands that stabilize the reduced complex. At low potential, the putative monovalent [Co(cyclam)]+ (cyclam = 1,4,8,11-tetraazacyclotetradecane) in NaOH solution catalyzes the reduction of both nitrate and nitrite to give mixtures of hydroxylamine and ammonia.100 Mixed N-donor systems bearing 7r-acceptor imine ligands in addition to amines are well known, but these examples are discussed separately in Section 6.1.2.1.3. 

D. Dimethylglyoxime.—The crude biacetyl monoxime, remaining after distilling to 90° and containing about 5 moles of biacetyl monoxime, is added to the sodium hydroxylamine monosulfonate solution (which has been filtered to remove any sediment) and which is contained in a 15-I. flask. It is heated to 70° and allowed to remain warm (with occasional stirring) for several hours (Note 9). The dimethylglyoxime separates in crystals which can be filtered from the solution as soon as it has become cold (Note 10). The crystals are washed with cold water until free of sulfate. The yield of compound melting at 238-240° is 540-575 g-... 

Benzenesulphohydroxamic Acid.1—Hydroxylamine hydrochloride (10 g.) is boiled under reflux condenser with just enough methyl alcohol to dissolve it, and when still hot is decomposed by a solution of 3 g. of sodium in 60 c.c. of ethyl alcohol, which should not be added too quickly. After the mixture has been cooled, precipitated sodium chloride is removed at the pump and 8-5 g. of benzenesulphonyl chloride are then added in small portions to the solution of free hydroxylamine. Most of the alcohol is now removed by distillation from the water bath, the hydroxylamine hydrochloride which has separated is removed by filtration, and the filtrate is evaporated to dryness in vacuo at a moderate temperature. The residue is extracted three times with 15 c.c. portions of boiling absolute ether. Evaporation of the combined ethereal extracts in an open dish yields the benzene sulphohydroxamic acid in the form of a mass of crystalline plates which are digested with cold chloroform and filtered with suction. Yield 5-6 g. Melting point 126°. 

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