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Related to Alkanes: Hydrocarbons



(also saturated hydrocarbons or paraffins), a homologous series of hydrocarbons of the general formula CnH2n + 2; part of the class of acyclic compounds. The parent compound of the series is methane, CH4. Each succeeding member is distinguished in composition from the preceding member by the constant difference CH2. The names of the first four members of the series are methane, CH4; ethane, C2H6; propane, C3H8; and butane, C4H10. The names of subsequent homologues are derived from the Greek cardinal numbers—for example, C5H12, pentane; C8H18, octane; C10H22, decane; and C16H34, cetane. The names of all alkanes end in “-ane.”

The carbon atoms in the molecules of alkanes are linked by single bonds to give straight unbranched chains or (starting with butane) branched chains. This is the reason for the existence of structural isomers in the alkane series. The number of isomers increases rapidly with the number of carbon atoms: pentane has three isomers, decane has 75, and eicosane (C20H42) has 366, 319. Starting with the heptanes, optical isomers also appear. The alkanes are colorless gases through butane and neopentane, liquids from C5H12 through C17H36, and solids thereafter. The boiling points of alkanes with branched chains are somewhat lower, and the melting points higher, than those of normal isomers. All alkanes are virtually insoluble in water but are readily soluble in numerous organic liquids.

Under normal conditions, alkanes are chemically the most inert hydrocarbons (hence the name “paraffins,” from the Latin parum, “little,” and affinitas, “affinity”). However, under relatively harsh conditions their hydrogen atoms may be replaced by other atoms and groups. Many such reactions are the basis of industrial processes for the manufacture of numerous important products. Chlorination of alkanes yields methyl chloride, methylene chloride, and chloroform; nitration yields nitroparaffins. Ultraviolet irradiation of a mixture of alkanes with sulfur dioxide and chlorine yields the sulfonyl chlorides, CnH2n + 1SO2CI. Oxidative sulfonation yields the sulfonic acids, CnH2n + 1 SO2-OH, and oxidation of the lower alkanes yields alcohols, aldehydes, ketones, and acids. Oxidation of solid alkanes to produce higher fatty acids is also of great industrial importance. Catalytic dehydrogenation of alkanes yields olefins (propylene, butenes, and amylenes) and diolefins (butadiene and isoprene); isomerization yields isobutane and isopentane. Alkylation of isobutane with olefins gives isooctane and neohexane. The lower alkanes are capable of forming inclusion compounds (clathrates) with water. Liquid and solid normal alkanes readily form clathrates with urea. This reaction is used in industry for deparaffination of petroleum products. Branched alkanes yield clathrates with thiourea.

Alkanes are present in petroleum (5–60 percent), which is the principal source for them. They are also produced during processing of hard coal, oil shale, and other materials. They are contained in plants and beeswax. The mineral wax ozokerite consists almost completely of higher alkanes. Natural gas contains up to 99 percent methane by volume.

Individual alkanes are prepared in the laboratory mainly by hydrogenation of olefins or by fusion of salts of fatty acids with caustic alkalies. Alkanes are important raw materials for the production of intermediates in making plastics, synthetic elastomers and fibers, and detergents. They are significant components of rocket and motor fuels and are used as solvents.


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Advanced analysis of alkanes revealed that branched alkanes rarely appeared in the pyrolysis products.
The use of plant wax alkanes as markers substances in studies of the nutrition of herbivores: A review.
The reaction of alkanes with this class of materials we've identified is novel," Periana said.
This equation allows the calculation of the mass transfer coefficient for the two alkanes (isooctane and cyclohexane) with suitable results, although these alkanes have different physical properties.
According to UW, the new process allows the desired alkanes to spontaneously separate from water without additional heating or distillation.
Breath samples were analyzed by gas chromatography and mass spectrometry to assess levels of alkanes and methylated alkanes.
This formulation of alkanes and alkanols reduces tack in milling, along with improved release from the mold by 20 to 30% over other previously used ordinary internal mold releases.
Oxidation of small molecule alkanes (CH4, C2H6, C3H8) and olefins (C2H6, C3H6)
29] alkanes is shown in Table 1, indicating the predominance of light hydrocarbons.
RESULTS: We found that 24-hr transition metals and alkanes were associated with increased odds [0.
provide an updated edition of their text on the chemistry of hydrocarbons: alkanes, alkenes, alkynes, and aromatics.
Because the different pasture species differ in their alkane patterns, and alkanes are largely indigestible during their passage through the herbivore's alimentary tract, the composition of a mixed herbage diet can be determined from the patterns of n-alkanes found in herbage and faeces (Dove and Mayes, 1996).