Decane, dehydrogenation

Modeling of n-decane dehydrogenation using Box-Wilson experimental design... 

Key words n-decane dehydrogenation, optimization of reaction parameters, model for n-decene yield, Box-Wilson design... 

An important support of the sextet model is that bicyclo[5.3.0]decane dehydrogenates on Pd (230) into an aromatic hydrocarbon, azulene, with but low yields. 

Bohlmann et al. (118-121) observed that an infrared absorption band between 2700-2800 cm is characteristic of a piperidine derivative possessing at least two axial carbon-hydrogen bonds in antiperiplanar position to the free-electron pair on the nitrogen atom. The possibility of forming an enamine by dehydrogenation can be determined by this test. Compounds which do not fulfill this condition cannot usually be dehydrogenated (50, 122,123). Thus, for example, yohimbine can be dehydrogenated by mercuric acetate,whereas reserpine or pseudoyohimbine do not react (124). The quinolizidine (125) enamines (Scheme 4), l-azabicyclo(4,3,0)-nonane, l-azabicyclo(5,3,0)decane, l-azabicyclo(5,4,0)undecane, and l-azabicyclo(5,5,0)dodecane have been prepared in this manner (112,126). 

The concept of site isolation is important in catalysis. On metal particles one usually assumes that ensembles of metal atoms are necessary to activate bonds and to accommodate the fragments of molecules that tend to dissociate or to recombine. We present here three examples of such effects the dehydrogenation of decane into 1-decene, the dehydrogenation of isobutane into isobutene and the hydrogenolysis of acids or esters into aldehydes and alcohols. In most cases the effect of tin, present as a surface alloy, wiU be to dilute the active sites, reducing thereby the yield of competitive reactions. 

The platforming catalyst was the first example of a reforming catalyst having two functions.43 44 93 100-103 The functions of this bifunctional catalyst consist of platinum-catalyzed reactions (dehydrogenation of cycloalkanes to aromatics, hydrogenation of olefins, and dehydrocyclization) and acid-catalyzed reactions (isomerization of alkanes and cycloalkanes). Hyrocracking is usually an undesirable reaction since it produces gaseous products. However, it may contribute to octane enhancement. n-Decane, for example, can hydrocrack to C3 and C7 hydrocarbons the latter is further transformed to aromatics. 

Dehydrogenation. Andersen et alreport that treatment of sesquiterpenes with trifluoroacetic acid leads to dehydrogenation with partial aromatization. The reaction is particularly suitable for production of tetralins. Thus treatment of the cadinene hydrocarbons (1)—44) in n-decane solution for a few minutes with excess TFA at room... 

Figure 16.2-3, n -dehydrogenation of 6. -m th)f hydrocortisones -ac 3te with pdyufetbarse-snti apped Artkwhactst simplex cells in buffer saturated 1-decanal. 

Monometallic Pt (0.4% w/w) and bimetallic Pt-Sn (0.4% 0.49% w/w respectively) catalysts supported on alumina have been modified with alkali metals ( Li, Na, K,Rb Cs, Pt alkali molar ratio of 1 40) have been investigated by TPR, TPD (ammonia and hydrogen), Pt dispersion and TPCO measurements and evaluation of activity for dehydrogenation of n-decane. Activity of alkali promoted mono and bimetallic catalysts are shown in Fig. 6 7 In the case of monometallic catalysts, Pt-Li system exhibits comparable initial actvity while the stability improves significantly. Other alkali elements do not show... 

Linear alkyl benzene (LAB) is manufactured by catalytic dehydrogenation of C10-C13 n-parafifins, followed by alkylation with benzene. High product selectivity, and reasonable catalyst life, in the dehydrogenation reaction, are obtained at the expense of conversion, by adjusting reaction parameters. Proper choice of reaction parameters is thus of paramount importance in this reaction. The present study, was carried out with n-decane, as model feed, and a promoted Pt/ALOs catalyst. A composite Box-Wilson experimental design was adopted to develop an empirical model for predicting monoene yield as a function of reaction conditions. Further, the model was used for determination of optimum reaction parameters. 

In conclusion, the Box-Wilson composite design is a convenient method for modeling of product yield as a function of reaction parameters (independent variables) especially when their number exceeds 2. In the dehydrogenation of n-decane, effect of reaction parameters on monoene selectivity / yield and n-decane conversion are represented satisfactorily by full II degree polynomial equations. The canonical form of the equations in the present study is indicative of an approximately stationary ridged system, with the reaction parameters close to center of design being optimum for monoene yield at conversion levels of 12 - 13 %. The polynomial equations were found to be consistent, with mechanistic considerations. 

The main part of the compound (decahydroazulene) decomposes and azulene forms, evidently, by dehydrogenation by the doublet mechanism. Thus, although the aromatic nature affects catalysis to a certain degree, it cannot by itself bring about a smooth dehydrogenation such as occurs in the case of cyclohexane. In order that catalysis take place, a structural correspondence is also necessary. Bicyclo[5.3.0]decane, contrary to cyclohexane, has no elements of symmetry common with with the lattice A1 of palladium and cannot superimpose on it. 

The complex RhCI(CO)(PMe3)2 successfully used for the dehydrogenation of alkanes, turned out to be an efficient catalyst for photochemical introducing a CO group into alkanes and arenes. Scheme lV-23 shows products of carbonylation of n-pentane, n-decane, 2-methylpentane, as well as benzene (yields are given based on Rh) [46a]. 

The development of blue colours in certain essential oils, e.g. oil of camomile, after such simple operations as distillation, steam distillation or treatment with acids or oxidising agents, has been noted at various times since the fifteenth century. Many such oils contain hydrogenated azulene derivatives (f,e. derivatives of bicyclo[5.3.0]decane) in their higher boiling fractions and the development of blue colours stems from dehydrogenation of these compounds. For example, an intensely blue coloured fraction, b.p. 

Starting with -hexane (Cg) metathesis, dehydrogenation should give the corresponding 1-hexene, followed by its homo-metathesis to yield ethylene and decene, which upon hydrogenation, should ideally produce ethane and decane (Cj q products) as the major products (Scheme 2.18, path a). However, this tandem reaction process was not selective since -decane represented <50% of the total primary products of heavy alkanes when the reaction was catalyzed with Ir-2(H2). The authors attributed this unexpected distribution of alkanes to the isomerization of the (x-olefin prior its metathesis, as depicted in pathway b (Scheme 2.18). 

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