2-Methylpropane, isomerization

Analogously, tnflic acid isomerizes n-butane into 2 methylpropane [80, 81] Interestingly, perfluorobutanesulfonic acid, which is of similar strength as tnflic acid, does not catalyze the isomerization of n-butane [50]... 

A typical feature of hydroformylation is the fact that both sides of the double bond are in principle reactive, so only ethene yields propanal as a single product. From propene, two isomers are formed linear or normal butanal and 2-methylpropanal (branched or iso product). With longer chain 1-alkenes, the isomerization of the double bond to the thermodynamically more favored internal positions is possible, yielding the respective branched aldehydes (Fig. 1). Frequently, terminal hydroformylation is targeted because of the better biodegradability of the products. Thus, not only stability, activity, and chemoselectivity of the catalysts are important. A key parameter is also the regioselectivity, expressed by the n/i ratio or the linearity n/(n+i). 

The boiling points of Isomeric haloalkanes decrease with increase In branching (Unit 12, Class XI). For example, 2-bromo-2-methylpropane has the lowest boiling point among the three Isomers. 

Butane (C4H10) can exist in two different isomeric forms, e.g. n-butane and isobutane (2-methylpropane). Open chain alkanes have free rotation about their C—C bonds, hut cycloalkanes cannot undergo free rotation, so substituted cycloalkanes can give rise to cis and trans isomers (see Section 3.2.2). 

The only available aldehyde data are for isomerization of butanal to 2-methylpropanal for which AHisom(g) = —11.0 1.7 kJmol-1. The corresponding alkene isomerization enthalpy of 1-pentene to 3-methyl-1-butene is —6.2 0.9 kJmol-1. Hydrogenating all... 

SbF5—Si02—AI2O3 has been used to isomerize a series of alkanes at or below room temperature. Methylcyclopentane, cyclohexane, propane, butane, 2-methylpropane, and pentane all reacted at room temperature, whereas methane, ethane, and 2,2-dimethylpropane could not be activated.111... 

The reaction of CH )NH2 with 2-methylpropanal can give three possible products two isomeric imines and an enamine. Since the products form reversibly, the reaction is thermodynamically controlled. Use SpartanView to obtain the energies of imine A, iminc B, and the enamine, and predict which is likely to be formed. What factors are responsible for the energy differences between the possible products ... 

The ramifications of Se transmetalations for chiral allenylstannanes are briefly summarized in Scheme 5.2.72 in which the common electrophile, (2f )-3-benzyloxy-2-methylpropanal, serves to selectively generate two distinct diastereoisomers 336 and 337. The reaction with (M)-286 and SnCU proceeds via anti-SE transmetalation followed by stereospecific isomerization to give the (P)-trichloroallenylstannane... 

Figure 27-5 Ball-and-stick models of the two isomeric C4H[q hydrocarbons, butane, CH3CH2CH2CH3, and methylpropane, CH3CHCH3.

Two or more compounds with the same molecular formula but different properties are called isomers. Isomers with different arrangements of bonded atoms are constitutional (or structural) isomers alkanes with the same number of C atoms but different skeletons are examples. The smallest alkane to exhibit constitutional isomerism has four C atoms two different compounds have the formula C4H10, as shown in Table 15.3 on the next page. The unbranched one is butane (common name, /t-butane n- stands for normal, or having a straight chain), and the other is 2-methylpropane (common name, i obutane). Similarly, three compounds... 

The method of selective absorption was also applied successfully to the isolation of isomeric compounds. The use of a selective absorber after the unsuccessful attempts at separation by conventional chromatographic methods made it possible to analyse the isomeric compounds 2-bromobutane and 1-bromo-2-methylpropane [91]. 

As Table 20.2 illustrates, the enol content of simple carbonyl compounds is quite small. Most exist almost entirely in their keto forms. Acetaldehyde contains less than 1 ppm of its enol, and acetone 100 times less than that. Each of the three simple aldehydes and ketones in the table (acetaldehyde, acetone, and 2-methylpropanal) has a single enol isomer. In many other cases stereoisomeric and constitutionally isomeric enols are possible. 

The fourth member of the alkane series, it has a straight chain of carbon atoms and is isomeric with 2-methylpropane (Cff3Cff(Cff3)Cff3, formerly ciled Isobutane). it can easily be liquefied under pressure and is supplied in cylinders for use as a fuel gas. It is dso a raw material for making buta-l,3-dlene (for synthetic rubber). 

A detailed mechanistic study of the carbon-chain isomerization during the electrochemical fluorination of two short-chain 1-sulfonyl fluorides, 2-methylpropane- and 2-methylethane-l-sulfonyl fluoride has been reported. This study gives insight into the complexity of this process and the... 

Figure 3.2. Representations of the isomeric hydrocarbons C4H10 (a) and (c) represent butane (n-butane) (b) and (d) represent 2-methylpropane (isobutane).

Where two compounds have the same molecular formula but different structural formulas (or different atom connectivities) they are said to be structural isomers. For example, propan-l-ol and propan-2 ol both have the molecular formula C3H3O, but the carbon atom to which the alcohol functional group (-OH) is attached in the hydrocarbon chain is different in the two molecules. We have also seen that hydrocarbon chains can be branched or straight, giving rise to structural isomerism for example, butane and Z-methylpropane are isomers with the same molecular formula (C4Hjo) (see Chapter 10). 

In studying both the electrophilic and nucleophilic nature of the sulfenic acid group, it was found that the sulfenic acid from 106 reacted with thiols (e.g., 2-methylpropane-1-thiol) to give a mixture of the disulfides 152 and 153 (Barton et al., 1970 1971a). The concomitant isomerization of the double bond appeared to be dependent upon both the side chain... 

In addition to butane isomerization, SbFs-treated metal oxides can catalyze the conversions of propane, 2-methylpropane (isobutane), pentane, 2-methylbutane (isopentane), hexane, cyclohexane, and methylcyclopentane at room temperatures. Methane, ethane and 2,2-dimethylpropane (neopentane), however, do not undergo any reactions over SbFs-treated metal oxides. 

The reaction mechanisms of hydrocarbon conversions over SbFs SiOz — AI2O3 were studied by coisomerization of perdeuterio and nondeuterio compounds coisomerization of pentane-do/di2, 2-methylbutane-db/di2, 2-methylpropane-di)/skeletal isomerizations, an intramolecular H (or D) transfer is involved in the rearrangements of the carbon skeletons, though the methyne H atom of 2-methylbutane and all H atoms of... 

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