Chloride as impurity

Insoluble iridium dioxide from the sodium peroxide fusion is dissolved in aqua regia, oxidized with nitric acid, and precipitated with ammonium chloride as impure ammonium hexachloroiridate(IV), To purify this salt, it is necessary to redissolve the compound and precipitate out the... 

Presence of hydrogen chloride as impurity causes an uncontrollable exothermic reaction dining preparation of diethyl phosphate from the title compound. 

Chloroform purified by the salicylide process contains no alcohol or ethyl chloride as impurities. 

B) Preparation of Glycine (M.). Use the same method as in section (A). Use a 500-ml Erlenmeyer flask and 10 times the quantities given for the semimicro preparation. After distillation of ammonia and further evaporation, the solution is treated with 0.5 g of charcoal and filtered. The residue is washed with 5 ml of hot water. The filtrate (about 100 ml) is placed in a beaker and 300 ml of methanol are added. After 24 hours the crude glycine is filtered, dried by suction, then pulverized while wet, suspended in 100 ml of methanol, and allowed to stand for an hour, with occasional stirring. The crystals are filtered, washed twice with 10 ml portions of methanol, and dried. The yield is about 25 g. The product prepared in this manner contains traces of ammonium chloride as impurities. If a very pure product is desired, the crystals are dissolved in 50 ml of boiling hot water, and the solution is treated with 1 g of charcoal and 0.5 g of Super-cel. It is then filtered with suction while hot and the solution diluted with 150 ml of methanol. The precipitated glycine is allowed to cool for an hour, filtered with suction, washed with 10 ml of methanol, and dried. The loss on recrystallization is 10-12 per cent. 

Infrared measurements have been conducted with sulphonyl chlorides obtained from, in determination of, sulphonate surfactants (see Section I.B.2.b above)161-163. IR measurements at 1212cm-1 were employed to determine p-chlorosulphonyl chloride as impurity in iV,iV-di-n-butyl-p-chlorobenzenesulphonamide2 81. 

If the reaction is carried out as a single-stage reaction starting from chlorobenzene, without isolation of the intermediate chlorobenzenesulfonyl chloride, care must be taken to ensure that sulfonic acid, thionyl chloride and sulfur chlorides, as impurities in the thionyl chloride, are no longer present in the reaction mixture, since the free sulfonic acid causes deactivation of the catalyst, and thionyl chloride and sulfur chlorides Ukewise lead to undesirable byproducts. A further difficulty is that iVA -dimethyl-formamide is required for complete conversion of chlorobenzenesulfonic acid with thionyl chloride into the corresponding sulfonyl chloride, carcinogenic A,A-dimethylcarbamyl chloride being formed as a byproduct. 

If the reaction is carried out as a single-stage reaction starting from chlorobenzene, without isolation of the intermediate chlorobenzenesulfonyl chloride, care must be taken to ensure that sulfonic acid, thionyl chloride, and sulfur chlorides, as impurities in the thionyl... 

Heating with cuprous chloride in aqueous hydrochloric acid isomerizes 2-butene-l,4-diol to 3-butene-l,2-diol (98)] Various hydrogen-transfer catalysts isomerize it to 4-hydroxybutyraldehyde [25714-71-0] (99), acetals of which are found as impurities in commercial butanediol and... 

Hydrogen Chloride as By-Product from Chemical Processes. Over 90% of the hydrogen chloride produced in the United States is a by-product from various chemical processes. The cmde HCl generated in these processes is generally contaminated with impurities such as unreacted chlorine, organics, chlorinated organics, and entrained catalyst particles. A wide variety of techniques are employed to treat these HCl streams to obtain either anhydrous HCl or hydrochloric acid. Some of the processes in which HCl is produced as a by-product are the manufacture of chlorofluorohydrocarbons, manufacture of aUphatic and aromatic hydrocarbons, production of high surface area siUca (qv), and the manufacture of phosphoric acid [7664-38-2] and esters of phosphoric acid (see Phosphoric acid and phosphates). 

Chlorine fluxing of aluminum to remove hydrogen and undesirable metallic impurities has largely been supplanted by fumeless fluxing procedures, which generally employ a low vapor pressure melt of alkaU chlorides containing a small amount of aluminum chloride as the active ingredient. 

A number of processes have been devised for purifying thionyl chloride. A recommended laboratory method involves distillation from quinoline and boiled linseed oil. Commercial processes involve adding various high boiling olefins such as styrene (qv) to react with the sulfur chlorides to form adducts that remain in the distillation residue when the thionyl chloride is redistilled (179). Alternatively, sulfur can be fed into the top of the distillation column to react with the sulfur dichloride (180). Commercial thionyl chloride has a purity of 98—99.6% minimum, having sulfur dioxide, sulfur chlorides, and sulfuryl chloride as possible impurities. These can be determined by gas chromatography (181). 

An alternative process for opening bastnasite is used ia Chiaa high temperature roastiag with sulfuric acid followed by an aqueous leach produces a solution containing the Ln elements. Ln is then precipitated by addition of sodium chloride as a mixed sulfate. Controlled precipitation of hydroxide can remove impurities and the Ln content is eventually taken up ia HCl. The initial cerium-containing product, oace the heavy metals Sm and beyond have been removed, is a light lanthanide (La, Ce, Pr, and Nd) rare-earth chloride. 

A group of workers at the institute for Macromolecular Chemistry at Brno, under the leadership of Vesely, began to report in 1955 on investigations into the polymerisation of isobutene. Most of this work has been done with aluminium chloride as catalyst at -78°. The technique used in the earliest work was rather crude, but it was later refined so as to ensure a reasonable degree of dryness. A commendable feature of this work is the attention given to the purity of the reagents and the specification - for some of them, at least - of the nature and concentration of impurities. 

Fabre, H., Blanchin, M. D., and Bose, N. (1999). Capillary electrophoresis for the determination of bromide, chloride and sulfate as impurities in calcium acamprosate. Anal. Chim. Acta 381, 29-37. 

Note Commerially available allyl alcohol may contain allyl chloride, 1-propanol and propanal as impurities. 

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