Carbon numbers

Nylon A class of synthetic fibres and plastics, polyamides. Manufactured by condensation polymerization of ct, oj-aminomonocarboxylic acids or of aliphatic diamines with aliphatic dicarboxylic acids. Also rormed specifically, e.g. from caprolactam. The different Nylons are identified by reference to the carbon numbers of the diacid and diamine (e.g. Nylon 66 is from hexamethylene diamine and adipic acid). Thermoplastic materials with high m.p., insolubility, toughness, impact resistance, low friction. Used in monofilaments, textiles, cables, insulation and in packing materials. U.S. production 1983 11 megatonnes. 

Their boiling points increase with the number of carbon atoms. For molecules of low carbon numbers, the addition of a carbon increases the boiling point about 25°C. Further additions result in a smaller increase. The density increases with the molecular weight 0.626 kg/1 for pentane which has 5 atoms of carbon, 0.791 kg/1 for pentacosane which has 25 carbon atoms, but the density is always much lower than 1. 

The sulfides are chemically neutral they can have a linear or ring structure. For molecules of equal carbon number, their boiling points are higher than those of mercaptans they constitute the majority of sulfur containing hydrocarbons in the middie distillates (kerosene and gas oil). 

The organophilic part R can come from a natural fatty acid whose carbon number is around 18 and whose chain contains a number of unsaturated bonds. Dimers of fatty acids (Cgg diacids) have also been used. 

Straight run diesei fuels have a high paraffin content, which is desirable, incidentally, for obtaining high cetane numbers. The higher the distillation end point, the higher is the heavy paraffin content (with a carbon number greater than C24). 

One can effectively reduce the tliree components to two with quasibinary mixtures in which the second component is a mixture of very similar higher hydrocarbons. Figure A2.5.31 shows a phase diagram [40] calculated from a generalized van der Waals equation for mixtures of ethane n = 2) with nomial hydrocarbons of different carbon number n.2 (treated as continuous). It is evident that, for some values of the parameter n, those to the left of the tricritical point at = 16.48, all that will be observed with increasing... 

Metallic Pd is a good catalyst for the conversion of the primary azide 34 into the nitrile 35 in the presence of a hydrogen acceptor such as diphenylacety-lene[33]. By this method, organic halides can be converted into nitriles without increasing the carbon number. Reaction of the azidoformate 36 with an allylic... 

The principal nonpolar-type adsorbent is activated carbon. Kquilihrium data have been reported on hydrocarbon systems, various organic compounds in water, and mixtures of organic compounds (11,15,16,46,47). With some exceptions, the least polar component of a mixture is selectively adsorbed eg, paraffins are adsorbed selectively relative to olefins of the same carbon number, but dicycUc aromatics are adsorbed selectively relative to monocyclic aromatics of the same carbon number (see Carbon, activated carbon). 

Primary human skin irritation of tetradecanol, hexadecanol, and octadecanol is nil they have been used for many years ia cosmetic creams and ointments (24). Based on human testing and iudustrial experience, the linear, even carbon number alcohols of 6—18 carbon atoms are not human skin sensitizers, nor are the 7-, 9- and 11-carbon alcohols and 2-ethylhexanol. Neither has iudustrial handling of other branched alcohols led to skin problems. Inhalation hazard, further mitigated by the low vapor pressure of these alcohols, is slight. Sustained breathing of alcohol vapor or mist should be avoided, however, as aspiration hazards have been reported (25). 

Shell Higher Olefin Process) plant (16,17). C -C alcohols are also produced by this process. Ethylene is first oligomerized to linear, even carbon—number alpha olefins using a nickel complex catalyst. After separation of portions of the a-olefins for sale, others, particularly C g and higher, are catalyticaHy isomerized to internal olefins, which are then disproportionated over a catalyst to a broad mixture of linear internal olefins. The desired fraction is... 

The Fischer-Tropsch process can be considered as a one-carbon polymerization reaction of a monomer derived from CO. The polymerization affords a distribution of polymer molecular weights that foUows the Anderson-Shulz-Flory model. The distribution is described by a linear relationship between the logarithm of product yield vs carbon number. The objective of much of the development work on the FT synthesis has been to circumvent the theoretical distribution so as to increase the yields of gasoline range hydrocarbons. 

This process yields a purely straight-chain acid of even carbon number. Typically, the value of n varies from two to six, and distillation yields the pure components. Du Pont pioneered the development of this technology. Allied has used hexafluoroacetone to produce telomer iodides containing the... 

Fig. 4. Product compositions as a function of carbon number for the Shell middle distillate synthesis process (a) the Fischer-Tropsch product following...

Naphthenic acids are lepiesented by a general formula where n indicates the carbon number and specifies a homologous series. The ... 

Higher olefins are versatile chemical intermediates for a number of important industrial and consumer products, providing a better standard of living with low environmental impact (qv) in many commercial uses. These uses can be characterized by carbon number and by chemical stmcture. 

Linear a-olefins were produced by wax cracking from about 1962 to about 1985, and were first commercially produced from ethylene in 1965. More recent developments have been the recovery of pentene and hexene from gasoline fractions (1994) and a revival of an older technology, the production of higher carbon-number olefins from fatty alcohols. 

The olefin distribution in the catalytic processes, on the other hand, tends to foUow the Schultz-Flory equation, where equals the number of moles of olefins having carbon number N, X equals the moles of olefins having two carbon numbers lower, andis a constant depending on the reaction conditions can range from 0.4—0.9 but usually equals 0.6—0.8. 

The solvent is 28 CC-olefins recycled from the fractionation section. Effluent from the reactors includes product a-olefins, unreacted ethylene, aluminum alkyls of the same carbon number distribution as the product olefins, and polymer. The effluent is flashed to remove ethylene, filtered to remove polyethylene, and treated to reduce the aluminum alkyls in the stream. In the original plant operation, these aluminum alkyls were not removed, resulting in the formation of paraffins (- 1.4%) when the reactor effluent was treated with caustic to kill the catalyst. In the new plant, however, it is likely that these aluminum alkyls are transalkylated with ethylene by adding a catalyst such as 60 ppm of a nickel compound, eg, nickel octanoate (6). The new plant contains a caustic wash section and the product olefins still contain some paraffins ( 0.5%). After treatment with caustic, cmde olefins are sent to a water wash to remove sodium and aluminum salts. 

Ethylene is recycled, some of which is purged, to eliminate the accumulation of ethane. The olefins are distilled into even-carbon-number fractions... 

Various blends of the C,—C, carbon numbers are also available. 1-Butene and 1-hexene are... 

These detergent range (C C ) odd and even linear internal olefins are fed to oxo-alcohol plants to produce C22 C2 semilinear alcohols. Most of the alcohols are ethoxylated and sold into detergent markets (8). Shell balances carbon numbers by a combination of the ethylene oligomerization extent. 

I/D unit operation, and alcohol carbon-number composition. 

SASOL. SASOL, South Africa, has constmcted a plant to recover 50,000 tons each of 1-pentene and 1-hexene by extractive distillation from Fischer-Tropsch hydrocarbons produced from coal-based synthesis gas. The company is marketing both products primarily as comonomers for LLDPE and HDPE (see Olefin polymers). Although there is still no developed market for 1-pentene in the mid-1990s, the 1-hexene market is well estabhshed. The Fischer-Tropsch technology produces a geometric carbon-number distribution of various odd and even, linear, branched, and alpha and internal olefins however, with additional investment, other odd and even carbon numbers can also be recovered. The Fischer-Tropsch plants were originally constmcted to produce gasoline and other hydrocarbon fuels to fill the lack of petroleum resources in South Africa. 

The conversion of fatty alcohols is approximately 99%. The reaction product is then condensed and sent to a distillation column to remove water and high boilers. Typically, a-olefin carbon-number distribution is controlled by the alcohol composition of the reactor feed. The process is currentiy used to produce a-olefins from fatty alcohols. A typical product composition is at <5%, at 50—70%, C g at 30—50%, C2Q at <2%,... 

---