With Alkanes

In addition to the reactions occurring in the pure components, new products with the empirical formulas CH P (n = 2 to 4) and CH PJ (n=1, 3 to 5) were observed in a PH3/CH4 mixture (molar ratio 1 3.2) by ion-cyclotron resonance spectroscopy at 70 eV. Both CHJ and fragment ions derived from PH3 react to generate the CHpP+ species. At the highest pressure of about 10 Torr, for example, CH and C2HJ react to form PHJ [23]. For details of the reactions of PH3 with the various cations, see Section 1.3.1.5.2, p. 219. Reactions observed upon neutron irradiation of PH3 in the presence of a large amount of CH4 are described in Section 1.3.1.5.1.5, p. 215. For an electric discharge in a PH3/H2O/NH3/CH4 mixture, see Section 1.3.1.5.6, pp. 245/6. 

Sparking a mixture of PH3 and CaHg (molar ratio 1 12) yields CH3PH2 and CgHgPHg. The total quantity of the alkylphosphanes equals roughly that obtained under similar conditions from a PH3/CH4 mixture [21]. The gamma irradiation of PH3 in a neopentane matrix is described in Section 1.3.1.5.1.6, p. 216. 

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Carboxoninm ions, for example, do not react with alkanes. However, in superacid solution acetaldehyde (or acetone), for example, readily reacts with isobutane involving diprotonated, highly reactive carbocationic species. 

Alkanes are so unreactive that George A Olahofthe University of Southern Cali forma was awarded the 1994 Nobel Prize in chemistry in part for developing novel substances that do react with alkanes... 

Table 4 2 lists the boiling points of some representative alkyl halides and alcohols When comparing the boiling points of related compounds as a function of the alkyl group we find that the boiling point increases with the number of carbon atoms as it does with alkanes... 

The reactivity of the halogens decreases m the order F2 > CI2 > Br2 > I2 Fluo rme is an extremely aggressive oxidizing agent and its reaction with alkanes is strongly exothermic and difficult to control Direct fluonnation of alkanes requires special equip ment and techniques is not a reaction of general applicability and will not be discussed further... 

Chlorination of alkanes is less exothermic than fluonnation and bromination less exothermic than chlorination Iodine is unique among the halogens m that its reaction with alkanes is endothermic and alkyl iodides are never prepared by lodmation of alkanes... 

Bromine reacts with alkanes by a free radical chain mechanism analogous to that of chlorine There is an important difference between chlorination and brommation how ever Brommation is highly selective for substitution of tertiary hydrogens The spread m reactivity among pnmary secondary and tertiary hydrogens is greater than 10 ... 

In contrast to the free radical substitution observed when halogens react with alkanes halogens normally react with alkenes by electrophilic addition... 

It IS instructive to compare the physical properties of ethers with alkanes and alcohols With respect to boiling point ethers resemble alkanes more than alcohols With respect to solubility m water the reverse is true ethers resemble alcohols more than alkanes Why" ... 

The way in which these factors operate to produce Type III isotherms is best appreciated by reference to actual examples. Perhaps the most straightforward case is given by organic high polymers (e.g. polytetra-fluoroethylene, polyethylene, polymethylmethacrylate or polyacrylonitrile) which give rise to well defined Type III isotherms with water or with alkanes, in consequence of the weak dispersion interactions (Fig. S.2). In some cases the isotherms have been measured at several temperatures so that (f could be calculated in Fig. 5.2(c) the value is initially somewhat below the molar enthalpy of condensation and rises to qi as adsorption proceeds. In Fig. 5.2(d) the higher initial values of q" are ascribed to surface heterogeneity. 

All lation with Alkanes. Superacids such as HF-SbF abstract hydride ion from alkanes to form carbocations at low temperatures. The... 

Elemental sulfur reacts with alkanes such as cyclopentane in the presence of superacidic trifluoromethanesulfonic acid to give symmetrical dialkyl sulfides in moderate yields. 

Extraction Solvent. Dimethyl sulfoxide is immiscible with alkanes but is a good solvent for most unsaturated and polar compounds. Thus, it can be used to separate olefins from paraffins (93). It is used in the Institute Fransais du Pntrole (IFF) process for extracting aromatic hydrocarbons from refinery streams (94). It is also used in the analytical procedure for determining polynuclear hydrocarbons in food additives (qv) of petroleum origin (95). 

Sulfur reacts with alkanes to either dehydrate (eq. 1), oxidize, forming carbon disulfide and hydrogen sulfide (eq. 2), or cyclize, forming thiophenes (eq. 3). The products of alkane sulfurization depend on the temperature, the time at the temperature, and the stmcture of the hydrocarbon (1). 

The mechanisms for the reaction of sulfur with alkanes and unsaturated compounds are highly speculative, being strongly influenced by the specific stmcture of the substrate and by the conditions (particularly temperature) of reaction. Alkane (4), olefin (5), animal fat (6), and vegetable oil (7) sulfurization have been extensively studied because these reactions are models for vulcanization. Moreover, the products are used as lubricant additives. 

Bromine reacts direcdy with alkanes but this reaction has Httle value because mixtures are obtained. However, photochemical bromination of alkyl bromides can be quite selective (23). 

Reactions of alkanedicarboxylic acids with sulfur tetrafluoride afford, in general, mixtures of bis(trifluorQmethyI)allcanes, cyclic 0(,a,a, a -tetrafluoro ethers, linear bis(pentafluoroalkyl) ethers, and polyfluoroethers The cyclic ethers constitute the major products of the reactions with alkane-1,2 dicarboxyhc acids, they are also formed in the reactions with alkane-1,3-dicarboxylic acids but not with 1,1- nor 1,4-dicarboxylic acids [211] (equation 105)... 

Chlorine gas reacts directly and highly exothermically with alkanes, giving rise to alkyl chlorides and hydrogen chloride, e.g., for addition to methane. 

In contrast with alkane chlorination, alkane bromination is usually much more selective. In its reaction with 2-methylpropane, for example, bromine abstracts the tertiary hydrogen with greater than 99% selectivity, as opposed to the 35 65 mixture observed in the corresponding chlorination. 

Chirality center, 292 detection of, 292-293 Eischer projections and, 975-978 R,S configuration of, 297-300 Chitin, structure of, 1002 Chloral hydrate, structure of, 707 Chloramphenicol, structure of, 304 Chlorine, reaction with alkanes, 91-92,335-338 reaction with alkenes, 215-218 reaction with alkynes, 262-263 reaction with aromatic compounds, 550 Chloro group, directing effect of, 567-568... 

As organic chemistry developed, it became apparent that some systematic way of naming compounds was needed. About 70 years ago, the International Union of Pure and Applied Chemistry (IUPAC) devised a system that could be used for all organic compounds. To illustrate this system, we will show how it works with alkanes. 

With alkanes containing a branched chain, such as... 

The alkanephosphonic acid dichlorides obtained by these methods are converted with amines, with all reactions carried out in solvents such as acetone, benzene, or diethyl ether at 10°C with triethylamine as HC1 captor. The conversion runs quantitatively followed by a purification with the help of column chromatography with chloroform/methanol in a ratio of 9 1 as mobile phase. The alkanephosphonic acid bisdiethanolamides could be obtained as pure substances with alkane residues of C8, C10, C12, and Ci4. The N-(2-hydroxyethane) alkanephosphonic acid 0,0-diethanolamide esters were also prepared in high purity. The obtained surfactants are generally stable up to 100°C. Only the alkanephosphonic acid bismonomethylamides are decomposed beneath this temperature forming cyclic compounds. 

This has also been accomplished with concentrated H2SO4 saturated with CO. Not surprisingly, only tertiary halides perform satisfactorily secondary halides give mostly rearrangement products. An analogous reaction takes place with alkanes possessing a tertiary hydrogen, for example. 

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