Naming Hydrocarbons

Butyne trimerizes in the presence of aluminum chloride to give hexamethyl Dewar-benzene (W. Schafer, 1967). Its irradiation leads not only to aromatization but also to hexa-methylprismane (D.M. Lemal, 1966). Highly substituted prlsmanes may also be obtained from the corresponding benzene derivatives by irradiation with 254 nm light. The rather stable prismane itself was synthesized via another hydrocarbon, namely benzvalene, a labile molecule (T. J. Katz, 1971, 1972). 

Radicals from Ring Systems. Univalent substituent groups derived from polycyclic hydrocarbons are named by changing the final e of the hydrocarbon name to -yl. The carbon atoms having free valences are given locants as low as possible consistent with the fixed numbering of the... 

Esters are named by replacing the ending -ic acid with the suffix -ate. The alcohol portion of the ester is named by replacing the -ane ending of the parent hydrocarbon name with the suffix -yl. The alkyl radical name of an ester is separated from the carboxylate name, eg, methyl formate for HCOOCH. Amides are named by changing the ending -oic acid to -amide for either systematic or common names, eg, hexanamide and acetamide. 

Mono-, di-, and triunsaturated fatty acids are named with Arabic numeral locants for the unsaturated positions and with the suffix -enoic, -adienoic, and -atrienoic acid in place of the -ane ending of the saturated hydrocarbon name, eg, 10,12,14-octadecatrienoic acid. 

For bicyclic structures the von Baeyer name consists of the prefix bicyclo-, followed in square brackets by the numbers of carbon atoms separating the bridgeheads on the three possible routes from one bridgehead to the other, followed in turn by the name of the alkane (or other homogeneous hydride, or repeating unit hydride) containing the same number of atoms in the chain as the whole bicyclic skeleton (examples 55-57). Replacement nomenclature can be applied to hydrocarbon names (example 58). 

The ethers are a group of compounds with the general formula R-O-R . The R, of course, stands for any hydrocarbon backbone, and the R also stands for any hydrocarbon backbone, but the designation R is used to indicate that the second hydrocarbon backbone may be different from the first. In other words, both the hydrocarbon backbones in the formula may be the same, but the is used to indicate that it may also be different. R-O-R as the general formula for the ethers is also correct. The fact that there are two hydrocarbon backbones on either side of an oxygen atom means that there will be two hydrocarbon names used. 

Aldehydes and ketones For aldehydes, identify the parent hydrocarbon include the C of—CHO in the count of carbon atoms. Then change the final -e of the hydrocarbon name to -al. The C in the —CHO group is always carbon l, at the end of a carbon chain, and is not explicitly numbered. For ketones, change the -e of the parent hydrocarbon to -one and number the chain in the order that gives the carbonyl group the lower number. Thus, CH3CH2CH2COCH3 is 2-pentanone. 

Ethylenic hydrocarbons, naming, 18 594 Ethylenic poly(disulfide)s, water-insoluble, 23 714... 

Taking all these considerations into account, it is possible to postulate a general mechanism for the oxidation of aliphatic hydrocarbons namely,... 

A whole lubricating oil fraction consists of four major classes of hydrocarbons—namely (a) asphalts and resins, (b) aromatics, (c) naphthenes and branched paraffins, and (d) paraffin wax. Sulfuric acid is remarkably effective for removing undesirable constituents a and b by a combination of reaction and extraction and has little or no effect on wax (which must be removed by other means) or the naphthenic-type materials which comprise a good lubricating oil. 

As was mentioned, cycloaddition of unactivated hydrocarbons, namely, that of cyclopentadiene, has practical significance. 5-Vinyl-2-norbomene is produced by the cycloaddition of cyclopentadiene and 1,3-butadiene546,547 [Eq. (6.96)] under conditions where side reactions (polymerization, formation of tetrahydroindene) are minimal. The product is then isomerized to 5-ethylidene-2-norbomene, which is a widely used comonomer in the manufacture of an EPDM (ethylene-propylene-diene monomer) copolymer (see Section 13.2.6). The reaction of cyclopentadiene (or dicyclopentadiene, its precursor) with ethylene leads to norbomene548,549 [Eq. (6.97)] 550... 

Stelzner Method. This is a general method of applying replacement nomenclature to ring systems it differs from the Chemical Abstracts procedure in that replacement principles are applied in all cases to the name of the hydrocarbon with the same bond distribution in the rings as the heterocycle to be named. This leads to no difference for monocycles (see examples 1-3), but in the case of fused skeletons the parent hydrocarbon of a fully unsaturated heterocycle is frequently a partially hydrogenated molecule. The parent hydrocarbon name for application of either replacement method can be trivial or a name derived by fusion principles (as above). The examples 21-24 of both... 

Univalent radicals derived from cycloalkanes (with no side chains) are named by replacing the ending -ane of the hydrocarbon name by -yl , the carbon atom with the free valence being numbered as 1. The generic name of these radicals is cycloalkyl . 

Monospiro compounds consisting of only two alicyclic rings as components are named by placing spiro before the name of the normal acyclic hydrocarbon of the same total number of carbon atoms. The number of carbon atoms linked to the spiro atom in each ring is indicated in ascending order in brackets placed between the spiro prefix and the hydrocarbon name. 

On the basis of this portion of Rule 4, the hydrocarbon name 6-p-menthene (designating a bond between ring carbons 6 and 1) cannot arise, because there is nothing to prevent the formula being drawn with the bond between ring carbons 1 and 2 (Rule 2 above). The correct name for the hydrocarbon, therefore, would be 1-p-menthene. 

Rule 1 Form the names of univalent radicals derived from menthane (the saturated parent hydrocarbon of menthane-type monocyclic terpenes) by replacing the ane ending of the hydrocarbon name with "y/ . That is menthyl. 

Rule 2 Form the names of univalent radicals derived from the unsaturated menthane-type monocyclic terpene hydrocarbons containing one double bond, which may be either in the ring or outside the ring, by replacing the final e" of the hydrocarbon name (menthene) with "yV That is menthenyl. 

To discern how many carbon atoms are in a straight chain or branch of a carbon compound, prefixes are used. If all the carbon-carbon bonds are single bonds, the hydrocarbon name ends in -ane. These molecules are called alkanes. If there is a double carbon-carbon bond, the name ends vn-ene. These molecules are called alkenes. If there is a triple carbon-carbon bond, the name ends in -yne. These molecules are called alkynes. 

Explain how to write a chemical formula using a hydrocarbon name (see Table 5.1, p. 207). In the explanation, describe the general formulas and rules for naming alkanes, alkenes, and alkynes. 

The correct numbering shows us that the branch comes from the third carbon atom in the straight chain. Therefore, the hydrocarbon name begins with the number 3. There is one carbon atom in the branch, so the branch name begins with meth- and ends in -y/—methyl. The straight chain has six carbon atoms (hex-) with only single bonds (-ane), so it is named hexane. Put it all together and we have 3-methylhexane. 

In a hydrocarbon name, the prefix tells how many carbon atoms are in the molecule, and the suffix tells how many carbon and hydrogen atoms are in the molecule. The general formula for alkanes is CnH2n+2, the general formula for alkenes is C H2n, and the general formula for the alkynes is C H2n,2. 

Mechanism. The mechanism for the formation of the low molecular weight aromatic hydrocarbons, namely ionene and the dimethylnaphthalene compounds can be explained by the scheme of Edmunds and Johnstone (22), advanced by Vetter et al. (35). The mechanism involves cyclizatlon with twelve electron systems followed by rearrangement to a four-ring intermediate, which leads to the formation of di-methycyclodecapentaene. This leads to the expulsion of ionene and dimethylnaphthalene from the carotene molecule as volatiles and the resulting nonvolatile component has been reported (13). 

The second class of volatile products observed were hydrocarbons, namely the ionene compounds. The formation of these hydrocarbons during heating is also reflective of deodorization and frying conditions. The formation of low molecular weight aromatic hydrocarbons results from fragmentation of the carotene molecule. The losses of toluene and ionene compounds from B-carotene yield do-decahexaene and octatetraene, respectively. These nonvolatile degradation products have been previously reported in our laboratory (13, 14). 

---