Alkanes, also

Alkanes also react with halogens to form substitution products. 

Natural gas is an abundant source of methane, ethane, and propane. Petroleum is a liquid mixture of many hydrocarbons, including alkanes. Alkanes also occur naturally in the waxy coating of leaves and fruits. 

Branched-chain alkanes, also known as isoparaffins or isoalkanes, are possible when n > 4. The prefix iso is used when two methyl groups are attached to a terminal carbon atom of an otherwise straight chain and the prefix neo when three methyl groups are attached in that manner. Branched-chain alkanes are sometimes regarded as normal alkanes with attached substituent alkyl groups. An example is... 

Oxidative Dehydrogenation of Ethane. The dehydrogenation of alkanes also occurs, but in a catalytic manner, over molybdenum supported on silica (22,23). In addition to the stoichiometric reactions, the role of the 0 ion in this catalytic reaction is further suggested by the observation that N2O is an effective oxidant at temperatures as low as 280°C, but no reaction is observed at these temperatures with O2 as the oxidant (22). It should be noted that at moderate temperatues N2O gives rise to 0 , whereas O2 yields O2 over Mo/Si02. Under steady-state conditions the rates of formation of C2Hi were in the ratio of 7 1 at 375°C and 3.7 1 at 450°C when N2O and O2 were used as the oxidants, respectively (23). ... 

Hydroboration of alkenes in non-ethereal solvent has been reported using diborane generated in situ from a quaternary ammonium borohydride and bromoethane (see Section 11.5). Almost quantitative yields of the alcohols are reported [e.g. 1 ]. As an alternative to the haloalkane, trimethylsilyl chloride has also been used in conjunction with the ammonium borohydride [2]. Reduction of the alkene to the alkane also occurs as a side reaction (<20%) and diphenylethyne is converted into 1,2-diphenylethanol (70%), via the intermediate /ra 5-stilbene. 

Alkanes (also called normal paraffins or n-paraffins). These constituents are characterized by branched or unbranched chains of carbon atoms with attached hydrogen atoms, and contain no carbon-carbon double bonds (they are saturated). Examples of alkanes are pentane (C5H12) and heptane (C7H16). 

The insertion products obtained by the photolysis of diazomethane in the gas phase in the presence of alkanes also include products originating from ethyl radicals, the formation of which must be explained by postulating vibrationally excited species The relative rates of abstraction of CH2 from alkanes are... 

The formulas of A and B correspond to which means these cire simple alkenes with no rings present. The formula for C (C H2 j) that of an alkane (also with no rings). 

Alkanes, also called paraffins, are composed of all C-C, saturated bonds and have the general formula C H2n+2. The naming conventions and typical properties of the first... 

Isomerization of straight-chain to branched alkanes also increases the octane number, as do alkylates produced by alkene-isoalkane alkylation (such as that of isobutane and propylene, isobutylene, etc.). These large-scale processes are by now an integral part of the petroleum industry. Refining and processing of transportation fuels became probably the largest-scale industrial operation. 

Branched acyclic alkanes also exhibit a slightly different behavior toward ozone on silica gel.105 Although tertiary alcohols are usually the main products, C—C bond cleavage to yield ketones always occurs and may become the predominant reaction. Atomic oxygen generated by microwave discharge of a C02/He mixture is a more selective reagent in the transformation of these compounds to tertiary alcohols.106... 

From the 13C chemical shift data collected in Table 4.1, Grant and Paul [85] deduced their additivity rule for the 13C chemical shifts of alkanes. The signal assignments for the alkanes, also given in Table 4.1, are based on signal intensities and proton decoupling experiments. 

Straight-chain alkanes also efficiently react with ozone in Magic Acid at —78°C in SO2CIF solution. Ethane gave protonated acetaldehyde as the major reaction product together with some acetylium ion (Scheme 5.62). Reaction of methane, however, is rather complex and involves oxidative oligocondensation to terf-butyl cation, which reacts with ozone to give methylated acetone (Scheme 5.63). 

Alkanes, also called paraffins or aliphatic hydrocarbons, are hydrocarbons in which the C atoms are joined by single covalent bonds (sigma bonds) consisting of two shared electrons (see... 

The use of another type of bis(trimethylsilylmethyl)amine leads to the synthesis of l-azabicyclo[m.3.0]alkanes also present in the skeleton of a number of alkaloids as trachelanthamidine, isoretronecanol, and tashiramine.447 451... 

Alkanes also undergo carboxylation with CO, as shown in Scheme 2. Carboxylation of alkanes to carboxylic acids is one of the interesting and important functionalization processes. The first example of carboxylation of alkanes was performed on cyclohexane using a Pd(0Ac)2/K2S208/TFA catalyst system [2]. This carboxylation reaction was extended to gaseous alkanes, for example methane, ethane, and propane. Thus, acetic acid (AcOH) was synthesized from methane and CO in the presence of a Pd catalyst but with a low conversion yield [3]. Recently, the acetic acid synthesis was much improved by using vanadium catalysts such as VO(acac)2 and afforded AcOH almost quantitatively [4],... 

The cage or window effect was proposed by Gorring (48) to explain the nonlinear effect of chain length observed in hydrocracking of various n alkanes over T zeolite, chabazite (CHA) and erionite (ERI). Thus, when a nC22 alkane is cracked over erionite, there are two maxima in the size distribution of the product molecules at carbon numbers of 4 and 11 and a minimum at carbon number of 8. The diffiisivities of n-alkanes also change in a similar periodic manner by over two orders of magnitude between the minimum at C8 and the maxima. This shows that for diffusion, and hence for shape selective effects, not only the size but also the structure of the reactant and product molecules need to be considered. 

The protolytic cracking involves the attack of the zeolitic proton to a carbon atom of the alkane molecule and the simultaneous rupture of one its adjacent C-C bond. The carbon atom being attacked and the C-C bond being broken will be preferentially those which produce the most stable carbenium ion. As for the dehydrogenation reaction, the protolytic cracking of linear and branched alkanes also follow different mechanisms, the latter ones producing olefins instead of alkoxides. 

The alkanes also react with elemental halogens at high temperatures to produce halogenated hydrocarbons. For example ... 

Photolysis of alkane/S02 mixtures leads to the formation of alkylsulfonic acids,the Hostapon process utilizing SOdOilhvP It is curious that this reaction seems to be so efficient, given the low e for alkane and SO2 at the wavelengths used, and an efficient chain reaction is presumably involved. The Reed reaction uses SO2/CI2/I11 to convert alkanes to the corresponding sulfonyl chlorides. Alkanes also react with SO3 to give alkyl sulfonates, sulfones and sulfates. ... 

Kolbe electrolytic reaction " for the synthesis of alkanes also involves the radicals as intermediates. For example, when a solution of diphenylacetic acid (2.41) is electrolyzed in DMF (dimethylformamide), the product 2.42 is obtained in 24% yield. 

More recent psec data (20) show that excited singlet states of the alkane also transfer singlet energy to the aromatic solute and that the rate of energy transfer is extremely rapid (k 10 LM S" ). 

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