Acyclic alkanes alkylation

Dehydrocyclization, 30 35-43, 31 23 see also Cyclization acyclic alkanes, 30 3 7C-adsorbed olefins, 30 35-36, 38-39 of alkylaromatics, see specific compounds alkyl-substituted benzenes, 30 65 carbene-alkyl insertion mechanism, 30 37 carbon complexes, 32 179-182 catalytic, 26 384 C—C bond formation, 30 210 Q mechanism, 29 279-283 comparison of rates, 28 300-306 dehydrogenation, 30 35-36 of hexanes over platintim films, 23 43-46 hydrogenolysis and, 23 103 -hydrogenolysis mechanism, 25 150-158 iridium supported catalyst, 30 42 mechanisms, 30 38-39, 42-43 metal-catalyzed, 28 293-319 n-hexane, 29 284, 286 palladium, 30 36 pathways, 30 40 platinum, 30 40 rate, 30 36-37, 39... 

Cycloalkanes are named much like acyclic alkanes. Substituted cycloalkanes use the cycloalkane for the base name, with the alkyl groups named as substituents. If there is just one substituent, no numbering is needed. 

Branched-chain alkane (Section 4.1 A) An acyclic alkane that has alkyl substituents bonded to the parent carbon chain. 

Fig. 4.23 Major hydrocarbons and simple heteroatomic compounds in crude oils (a) acyclic alkanes (paraffins) (b) cycloalkanes (naphthenes) (c) aromatic hydrocarbons (d) sulphur-containing aromatics. (R. = alkyl group.)...

The acyclic alkanes produced by defunctionalization and reduction of fatty acids retain some source-related information by way of their carbon numbers and positions of any branch points in the alkyl chains. For example, the OEP observed in higher plant wax n-alkanes (>C22) is augmented by the decarboxylation (i.e. loss of one C atom) of wax-derived fatty acids with an EOP. 

The dehydrogenation of acyclic alkanes is at one and the same time both simpler and more complex than any of the reactions so far considered it is simpler in the sense that the mechanism for the formation of alkenes involves only adsorbed alkyl radicals, alkenes and hydrogen atoms, and with rare exceptions lacks any of the subtlety so common with hydrogenations but it is more complex... 

E. ROTATION ABOUT SIGMA (a) BONDS IN ACYCLIC ALKANES, ALKENES, ALKYNES, AND ALKYL-SUBSTITUTED ARENES... 

A greater selectivity was observed with the complex Cp (PMe3)RhH2 7, the rhodium analogue of 4, which was independently studied by Bergman [22] and Jones [23]. Apparently only primary CH bonds of acyclic alkanes are activated by the rhodium complex (reaction 10) the hydrido alkyl products are more unstable towards reductive elimination of RH than their iridium analogues and must be prepared and characterized below -20 °C. 

These reactions also lead to the formation of alkyl chlorides and acetates. Cycloalkanes are more reactive than acyclic alkanes primary CH bonds were found to react faster than secondary CH bonds. Because of the presence of platinum metal, which sometimes precipitates, these reactions were suspected to be heterogeneous. Shilov demonstrated that Pt(TV) and Pt(0) are inactive in these exchanges it is now accepted that these reactions may involve an oxidative addition step. 

Sheppard N and De La Cruz C 1998 Vibrational spectra of hydrocarbons adsorbed on metals. Part II. Adsorbed acyclic alkynes and alkanes, cyclic hydrocarbons including aromatics and surface hydrocarbon groups derived from the decomposition of alkyl halides, etc Adv. Catal. 42 181-313... 

Alkyl groups of compounds other than alkanes can be regioselectively functionalized using C-H activation chemistry. For example, acyclic and cyclic ethers can be activated by Ir(m) complexes to yield carbene complexes (Equation (25)).35... 

Part II. Adsorbed Acyclic Alkynes and Alkanes, Cyclic Hydrocarbons Including Aromatics, and Surface Hydrocarbon Groups Derived from the Decomposition of Alkyl Halides, etc. 

Alkanes and cycloalkanes. Obviously a variety of acyclic and cyclic hydrocarbon structures can be synthesized from the appropriate alkyl- or aryl-thiophenes (Scheme 46). The reaction is especially useful for the construction of macrocycles (Scheme 47). One of the most interesting applications of this reaction is in the synthesis of the chiral hydrocarbon butylethylmethylpropylmethane (210) (80JOC2754). The chiral acid (209) was the precursor, in which the thiophene was the potential n-butyl group. Raney nickel desulfurization, followed by standard manipulations to convert the acetic acid unit into an ethyl group, gave the hydrocarbon (210) (Scheme 48) this had [a]578 = -0.198°. It was established that... 

Activation of two Si—Si bonds in bis(disilanyl)alkanes with palladium(O) bis(tert-alkyl isocyanide) induced the formation of the cyclic bis(silyl)palladium(II) bis(terf-alkyl isocyanide) complexes (100) and disilanes described schematically in Scheme 42. These complexes were found to react with phenylacetylene, affording different amounts of five-membered cyclic products and acyclic products which are derived from the insertion of the alkyne into the general intermediate complex 101 (Scheme 42, equation 54). The bis(silanyl)dithiane palladium complex (102) was isolated and characterized in the solid state the two silicon atoms, the two isocyano carbons and the palladium atom are nearly in a plane with a short cross-ring Si—Si distance of 2.613(2) A, suggesting the possibility of covalently bonded two Si—Si atoms in the four-membered ring. Similar reaction with cyclic disilanes afforded oligomers, and cyclic 20-membered compounds have been prepared in the presence of nitriles248,249. 

Isomer enumeration methods have been reviewed several times. The literature till 1973 is summarized in Rouvray s excellent and comprehensive review [3] which emphasizes the dassical methods for enumerating alkanes and alkyl derivatives a similar approach is contained in Trinaj-stid s recent book [4]. In a book edited by the present author in 1976, three chapters were devoted to this problem one dealing with Pdlya s contributions to the field [5a], a second with the enumeration of acyclic systems [5b], and a third with the enumeration of cyclic systems [5c]. Since that time considerable progress has been made in the latter area. Accordingly, the present review will stress these more recent applications, while trying to reduce repetition of previously reviewed work to the minimum necessary to make the present chapter intelligible and self-contained. 

Reactions of acyclic hydrocarbons of various skeletal structures with CO in superacid media were recently studied by Yoneda and coworkers " as discussed in the previous section. Products obtained were only isomeric carboxylic acids with lower number of carbon atoms than the starting alkanes. Formation of the carboxylic acids were accounted by the reactions of parent, isomerized and fragmented alkyl cations with CO to form the oxocarbenium ion intermediates (Koch-Haaf reaction) followed by their quenching with water. No formylated products in these reactions have been identified. 

Unknown 9.1, an acyclic isoprenoid alkane useful as a chemical fossil (Robson and Rowland 1986), illustrates the fact that methyl branching has little effect on the mass spectrum in the presence of substitution by larger alkyl groups. Does more than one combination of such substitution fit ... 

---