Hydrogen laboratory preparation

IV) oxide, the latter being used in the eommon laboratory preparation of oxygen from hydrogen peroxide (p. 260. ... 

Intermediate formation of formyl chloride is not necessary since the actual alkylating agent, HCO", can be produced by protonation of carbon monoxide or its complexes. However, it is difficult to obtain an equimolar mixture of anhydrous hydrogen chloride and carbon monoxide. Suitable laboratory preparations involve the reaction of chlorosulfonic acid with formic acid or the reaction of ben2oyl chloride with formic acid ... 

Commercial manufacture of methyl bromide is generally based on the reaction of hydrogen bromide with methanol. For laboratory preparation, the addition of sulfuric acid to sodium bromide and methanol has been used (80). Another method involves the treatment of bromine with a reducing agent, such as phosphoms or sulfur dioxide, to generate hydrogen bromide (81). 

Hydrogen is prepared in small amounts in the laboratory by reducing hydrogen ions from a strong acid (such as hydrochloric acid) with a metal that has a negative standard potential, such as zinc ... 

This is a convenient laboratory preparation of hydrogen cyanide tetramer that avoids the hazards in using hydrogen cyanide itself. Hydrogen cyanide tetramer is a useful intermediate for the synthesis of heterocycles such as imidazoles5- 6 and thiadiazoles.7... 

This procedure illustrates a general method for preparing olefins by the elimination of an amine and a /3-hydrogen atom." The present method is more convenient for adaptation to large-scale laboratory preparation than is the Wittig modification, which utilizes liquid ammonia both methods give essentially the same overall yield of iraw5-cyclooctene. 

Dibenzothiophene is now commercially available. However, laboratory preparations from biphenyl, sulfur, and aluminum chloride have continued to be studied, yields of up to 80 being recorded. The synthesis from biphenyl and hydrogen sulfide in the presence of a catalyst has also been reinvestigated. ... 

Both older methods for the reduction of esters to alcohols, catalytic hydrogenation and reduction with sodium, have given way to reductions with hydrides and complex hydrides which have revolutionized the laboratory preparation of alcohols from esters. 

The method, described relatively early, for the preparation of phosphine using the reaction of hot concentrated alkalies, such as NaOH, KOH or Ca(OH)2, on white phosphorus can also be used for the laboratory preparation. This method also produces a steady stream of phosphine, which, however, may be contaminated by up to 90% hydrogen and traces of P2H4 >>3.8s.ioi-io6) phine formed from the thermal decomposition of phosphorous or hypophos-phorous acids or their salts is similarly contaminated with hydrogen. In cases where hydrogen interfers, the phosphine can be purified by condensation and distillation. 

The reaction between dry phosphine and hydrogen iodide, first described in 1817 by J. J.Houtonde la Billardiere produces phosphonium iodide. The simplest laboratory preparation of this compound is by the hydrolysis of an intimate mixture of diphosphorus tetraiodide and white phosphorus According to X-ray diffraction investigations, phosphonium iodide crystallises in a caesium chloride type lattice 3m,32s). 326) hydrogen atoms... 

Iron(II) sulfide occurs in nature as the minerals magnetkies, troilhte and pyrrhotine. The most important application of this compound is in Kipp s apparatus as a source for laboratory preparation of hydrogen sulfide. It also is used in paints, pigments, and ceramics and lubricant coatings. 

The only practical laboratory preparation of cyclopentadiene is by the depolymerization of dicyclopentadieneA M 3-Chloro-cyclopentene has been prepared by the addition of hydrogen chloride to cyclopentadiene.2 7 8 9 10... 

Hydrogen for industrial purposes is produced by the steam-hydrocarbon re-forming process and is used in the synthesis of ammonia and methanol. In the laboratory, hydrogen is prepared by reaction of dilute acid with an active metal, such as zinc. 

The direct replacement of the hydroxyl group in simple phenols by an amino or substituted amino group requires drastic conditions and the method is not suitable for laboratory preparations. With the polyhydric phenols, and more particularly with the naphthols, such replacements occur more readily. Thus 2-naphthol is converted into 2-naphthylamine by heating with ammoniacal ammonium sulphite solution at 150°C in an autoclave. The reaction (the Bucherer reaction) depends upon the addition of the hydrogen sulphite ion to the keto form of the naphthol and the subsequent reaction with ammonia. 

Carbonyl fluoride can be prepared by any of several methods, including the conversion of carbonyl chloride to the fluoride by such reagents as hydrogen fluoride1 and antimony (III) fluoride.2 The direct combination of carbon monoxide and fluorine is another route to this fluoride, but carbon tetrafluoride is a by-product of the reaction.8 A particularly suitable laboratory preparation of carbonyl fluoride is the fluorination of carbon monoxide by silver (II) fluoride.4 This method, described below, gives directly carbonyl fluoride of rather high purity without recourse to a low-temperature distillation. 

An improved procedure for the laboratory preparation of 2,5-dimethylpyrazine has been reported.166 a-Amino alcohols are convenient precursors for the industrial preparation of alkylpyrazines. Thus when they are heated in the vapor phase with copper chromite catalysts, they are converted mainly into pyrazines [Eq. (8)] with hydrogenation catalysts such as Raney nickel, piperazines are the... 

Already familiar is the convenient laboratory preparation of elementary hydrogen by reduction of acids. Generally those metals lying between magnesium and tin in oxidation potential are appropriate. Less convenient but more spectacular is the production of hydrogen from action of the alkali metals on water. For small quantities of hydrogen, reaction of metal hydrides with water has been used such hydrides will be considered later in the chapter. Commercial preparations of H2 by reduction of steam with iron or coke and, finally, by the electrolysis of water should be recalled. 

It is thus produced during the commercial purification of coal gas from sulphuretted hydrogen.2 In the laboratory preparation of the pure substance the reaction should be continued for several hours in the absence of air, the precipitated sulphide being black when the reaction is complete.3... 

Boron Trichloride. Boron trichloride is prepared commercially by the chlorination of boron carbide (equation 15). Direct chlorination of boric acid or a sodium borate in the presence of carbon is an alternative method. Most of the boron trichloride produced is converted to filaments of elemental boron by chemical vapor deposition (CVD) on tungsten wire in a hydrogen atmosphere. Numerous laboratory preparations of boron trichloride have been reported. One of the most convenient is the halogen exchange reaction of aluminum chloride with boron trifluoride or a metal fluoroborate. 

Hydrogen is prepared in a variety of ways, most commonly from water, acid, hydroxide bases, and hydrocarbons. The most frequently used laboratory preparations are as follows. 

In our study of organic chemistry, we shall concentrate our attention on versatile laboratory preparations rather than on limited industrial methods. In learning these we may, for the sake of simplicity, use as examples the preparation of compounds that may actually never be made by the method shown. We may discuss the synthesis of ethane by the hydrogenation of ethylene, even though we can buy all the ethane we need from the petroleum industry. However, if we know how to convert ethylene into ethane, then, when the need arises, we also know how to convert 2-methyl-1-hexene into 2-methyl hexane, or cholesterol into cholestanol, or, for that matter, cottonseed oil into oleomargarine. 

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