Hydrogen producing

Some of ihe carbon monoxide and hydrogen produced in ihe steam-naphtha reforming process react to form methane ... 

Place a few drops of nitromethane in a test tube, add about 3 times as much concentrated hydrochloric acid, and then a piece of granulated tin. The tin dissolves in the acid and the nascent hydrogen produced reduces the nitromethane to monomethylamine ... 

Both aliphatic and aromatic nitro-compounds can be readily reduced in acid solution to the corresponding primary amine. Thus when a mixture of nitrobenzene and tin is treated with hydrochloric acid, the tin dissolves to give stannous chloride, SnCh, which in these circumstances then reacts with more acid to give stannic chloride, SnCl, and the nascent hydrogen produced from... 

The Pd—C cr-bond can be prepared from simple, unoxidized alkenes and aromatic compounds by the reaction of Pd(II) compounds. The following are typical examples. The first step of the reaction of a simple alkene with Pd(ll) and a nucleophile X or Y to form 19 is called palladation. Depending on the nucleophile, it is called oxypalladation, aminopalladation, carbopalladation, etc. The subsequent elimination of b-hydrogen produces the nucleophilic substitution product 20. The displacement of Pd with another nucleophile (X) affords the nucleophilic addition product 21 (see Chapter 3, Section 2). As an example, the oxypalladation of 4-pentenol with PdXi to afford furan 22 or 23 is shown. 

Uses. Furfural is primarily a chemical feedstock for a number of monomeric compounds and resins. One route produces furan by decarbonylation. Tetrahydrofuran is derived from furan by hydrogenation. Polytetramethylene ether glycol [25190-06-1] is manufactured from tetrahydrofuran by a ring opening polymeri2ation reaction. Another route (hydrogenation) produces furfuryl alcohol, tetrahydrofurfuryl alcohol, 2-methylfuran, and 2-methyltetrahydrofuran. A variety of proprietary synthetic resins are manufactured from furfural and/or furfuryl alcohol. Other... 

Reaction of MEK with ammonia and hydrogen produces j i -butylarnine, a fungistat and condensation with aUphatic esters under strongly alkaline conditions produces 1,3-diketones. 

Gyanoethylation. The reaction of primary fatty amines with acrylonitrile followed by hydrogenation produces diamines and ttiamines (4,7,31,32,37,38). 

The y -phenylenediamiaes are easily obtained by dinitrating, followed by catalyticaHy hydrogenating, an aromatic hydrocarbon. Thus, the toluenediamiaes are manufactured by nitrating toluene with a mixture of sulfuric acid, nitric acid, and 23% water at 330°C which first produces a mixture (60 40) of the ortho and para mononitrotoluenes. Further nitration produces the 80 20 mixture of 2,4- and 2,6-dinitrotoluene. Catalytic hydrogenation produces the commercial mixture of diamiaes which, when converted to diisocyanates, are widely used ia the production of polyurethanes (see Amines, aromatic, DIAMINOTOLUENES) (22). 

The source of nitrogen is always air. However, hydrogen can be derived from a variety of raw materials including water, light and heavy hydrocarbons (qv) resulting from cmde oil refining, coal (qv), natural gas, and sometimes a combination of these raw materials. In all cases, part of the hydrogen produced is derived from water. 

Hydrogen produced by the electrolysis of water is used in special circumstances only where electric power is plentiful, inexpensive, and light hydrocarbons are not available. 

Cyclodimerhation of isoprene to 1,5-dimethylcycloocta-1,5-diene and disproportion with a rhenium oxide catalyst and isobutene produce 2,6-dimethyUiepta-l,5-diene. The diene is hydroformylated to citroneUal, which after hydrogenation produces citroneUol (137). 

Fig. 4. Mild acid treatment of (+)-citroneUal (68) produces a mixture, 70% (-)-isopulegol (69), 23% (+)-neoisopulegol (70), 8% (+)-isoisopulegol (71), and 2% (+)-neoisoisopulegol (72). Catalytic hydrogenation produces (-)-menthol (73) from (69) (+)-neomentho1 (74) from (70) (+)-isomentho1 (75) from (71) ...

As an example the use of ceramic membranes for ethane dehydrogenation has been discussed (91). The constmction of a commercial reactor, however, is difficult, and a sweep gas is requited to shift the product composition away from equiUbrium values. The achievable conversion also depends on the permeabihty of the membrane. Figure 7 shows the equiUbrium conversion and the conversion that can be obtained from a membrane reactor by selectively removing 80% of the hydrogen produced. Another way to use membranes is only for separation and not for reaction. In this method, a conventional, multiple, fixed-bed catalytic reactor is used for the dehydrogenation. After each bed, the hydrogen is partially separated using membranes to shift the equihbrium. Since separation is independent of reaction, reaction temperature can be optimized for superior performance. Both concepts have been proven in bench-scale units, but are yet to be demonstrated in commercial reactors. 

A route to phenol has been developed starting from cyclohexane, which is first oxidised to a mixture of cyclohexanol and cyclohexanone. In one process the oxidation is carried out in the liquid phase using cobalt naphthenate as catalyst. The cyclohexanone present may be converted to cyclohexanol, in this case the desired intermediate, by catalytic hydrogenation. The cyclohexanol is converted to phenol by a catalytic process using selenium or with palladium on charcoal. The hydrogen produced in this process may be used in the conversion of cyclohexanone to cyclohexanol. It also may be used in the conversion of benzene to cyclohexane in processes where benzene is used as the precursor of the cyclohexane. 

Chemical Reactivity - Reactivity with Water Reacts violently with water as a dry solid or when dissolved in ether. The hydrogen produced by the reaction with water is a major hazard and necessitates adequate ventilation Reactivity with Common Materials Can burn in heated or moist air Stability During Transport Normally stable imstable at high temperatures Neutralizing Agerus for Acids and Caustics Not pertinent Polymerization Not pertinent Inhibitor of Polymerization Not pertinent. 

Hydrogen embrittlement is due to the reaction of diffused hydrogen with a metal. Different metals undergo specific reactions, but the result is the same. Reaction with hydrogen produces a metal that is lower in strength and more brittle. 

Hydrogen produced by con osion has also turned up in some unexpected places (see Section 16.2). 

Hydrogen produced by corrosion can turn up in unexpected places, as shown by the following incidents ... 

---