Methyl hexanes

Figure 10-8 Sequential (tlypothcticaP nydrogcnation of Cubane to, T4-Di methyl hexane.

The data in Table IV and Figure 1 indicate that most of the paraffin concentration reduction took place in the Ce to Ce range and involved monomethyl paraffins. The blending octane numbers for 2-methyl and 3-methyl hexanes are reported as 40 to 56 by ASTM ( ) and are lower than the blending numbers for light (Cs to C ) olefins and Ce to Cii aromatics. Thus, reduction in concentration of these branched paraffins is expected to improve the research octane number of the gasoline. 

To exhibit optical activity an alkane must contain at least one asymmetric carbon atom. Simplest optically active alkane is 3-methyl hexane. 

Runge Goldann (Ref 5) prepd by treating its tetrahydrazide (mp 230.5° with de compn) with Na N02 and HC1 at 8—10° Ethone-l,l,2,2-tetracetic Acid Hydrazide, called 3,4-Bis[(azidoformyl)methyl]hexane dial Azide in CA 5th. Decennial Formula Index, p 555F, N3OC.CH2.CH.CH,3.CON3... 

Methyl hexane Dimethyl pentane Monomethyl C7+ Dimethyl C6. Normal C8 ... 

EXAMPLE 4-1 Calculate the van der Waals constants for 3-methyl-hexane. 

From the point of view of the formation of the optically active 4-methyl-hexanal, it has been defined as a stereoelective (17) hydroformylation (I). 

LXXXI (+)(R)-6-Meth- oxy-4-methyl- hexanal-di- athylacetal c12h26o3 218,3 Chloro- form 0,0962 25 589 +3,78 ... 

CjHg — C — CjHg 3 - ethyl - 3 - methyl hexane C3H7... 

When optically active hydrocarbons have been used as substrates, a similar pattern of insertion reactivity emerges, nienylnitrene inserts with a maximum of 30% retention into the tertiary C—bond of optically active 2-phenylbutane implying a high degree of triplet involvement, whereas ethoxycarbo-nylnitrene inserts stereoselectively with 98-100% retention into the tertiary C—of (S)-(+)-3-methyl-hexane. The result is independent of the method of nitrene neration, and of concentration, and lends support to the view that only singlet ethoxycarbonylnitrene inserts into unactivated C—bonds. 

Hie reactions oonaidered in the previous two sections involve additions te achiral alkenea, and optically inactive products aru formed tn all cusea. would happen, though, if wc were to carry out a reaction on a vingle enab tiomer of a chiral reactant For example, what stereochemical result would, be obtained from addition of HBr to a chiral aikene, such as iff/-4-methyI l-trexene The product of the reaction, 2-bromo-d-methyl hexane, ha chirality centers and four possible stereoisomers. ... 

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