Alkanes cyclic/cyclo

The chain and branched chain saturated hydrocarbons make up a family called the alkanes. Some saturated hydrocarbons with five carbon atoms are shown in Figure 18-11. The first example, containing no branches, is called normal-pentane or, briefly, n-pentane. The second example has a single branch at the end of the chain. Such a structural type is commonly identified by the prefix iso- . Hence this isomer is called /50-pentane. The third example in Figure 18-11 also contains five carbon atoms but it contains the distinctive feature of a cyclic carbon structure. Such a compound is identified by the prefix cyclo in its name—in the case shown, cyclopentane. 

More recently, the same principle was applied by the same authors to cyclic alkanes for catalytic ring expansion, contraction and metathesis-polymerization (Scheme 13.24) [44]. By using the tandem dehydrogenation-olefin metathesis system shown in Scheme 13.23, it was possible to achieve a metathesis-cyclooligomerization of COA and cyclodecane (CDA). This afforded cycloalkanes with different carbon numbers, predominantly multiples of the substrate carbon number the major products were dimers, with successively smaller proportions of higher cyclo-oligomers and polymers. 

The estimates of the RSE for small cyclic alkanes, cyclo-olefins, and cyclic ethers using all three reactions are listed in Table 3.21. The failure of the isodesmotic reaction is readily apparent by examining the RSE of the cyclic alkanes. For the rings having five or more carbon atoms, the isodesmic method predicts that there is no strain energy. Rather, it predicts that these cyclic species are more stable than their acyclic counterparts. The homodesmotic and GE reactions, which are identical for the cyclic alkanes, provide RSEs in excellent agreement with CRSE estimates. 

All are named with a stem name and the suffix -ane. A cyclic (ring) alkane has the general formula (CH2) , and is designated by the prefix cyclo-. 

Cyclic alkanes, those that have the carbon atoms joined in a nonplanar ring (not aromatic), have the prefix cyclo-attached. 

The cyclic compounds for which most data are available are the cyclo-alkanes. Dainton, Devlin and SmalD ) ]iave calculated the change in heat and in free energy for the polymerization to linear polymers of unsubstituted and substituted cyclo-alkanes, viz.,... 

Substitution of extra-annular hydrogen atoms of the cyclic mono-ethers seems to have the same effect on the heat of polymerization as it does in the case of the cyclo-alkanes. Thus, for the 3,3-disubstituted-l-oxacyclobutanes the heats of polymerization are less than for the parent compound, trimethyiene oxide. 

These are alkanes in which the carbon atoms form a ring. The prefix cyclo- is used in the names of these compounds to indicate their cyclic nature. 

Molex n-, branched and cyclo alkanes n-paraffins Branched and cyclic isomers 5A sieve 4-light paraffin desorbent... 

There is a nomenclature dilemma for cyclic alkanes. The suffix for the name must be ane because they are alkanes. The normal prefix will indicate the presence of 3-12 carbons for the alkanes in Figure 4.4, so the names should be propane to dodecane. Those names have already been taken for the acyclic alkanes To distinguish between the linear 12-carbon molecule (dodecane) and the 12-membered cyclic (ring) alkane, use the term cyclo. If the ring is viewed as a cycle, then the prefix cyclo is used in front of the alkane name (a prefix in front of the carbon number prefix). The three-membered ring alkane therefore becomes cyclopropane and the 12-membered ring alkane becomes cyclododecane (see Figure 4.4). 

Cyclic alkenes are known compounds. As with cyclic alkanes, the parent name for cyclic alkenes is based on the number of carbon atoms in the ring derived from the analogous linear alkene, but the prefix cyclo is added to the name. The six-carbon cyclic molecule that contains a C=C unit is called cyclohexene (4). Substituents are named in the usual manner, and one carbon of the C=C unit must be Cl. The choice of which C=C carbon becomes Cl is dictated by giving the substituents the lowest number. Compound 5 is a cycloheptene, but the substituents can be numbered 6-ethyl-3,6-dimethyl- or 4-ethyl-4,7-di-methyl. The smaller numbers dictates the priority, which also give the ethyl group the lower number, and 5 is 4-ethyl-4,7-dimethylcycloheptene. Note that the 1-heptene is unnecessary in the name... 

CHI CsHii-n with zinc powder and ammonium chloride in aqueous ethanol or hot ethanolic sodium ethoxide yields the alkane n-C7Fi5 C7Hj5-n and the olefin n-C7Fi5 CH=CH C5Hu-n, respectively. The results of detailed studies on free-radical (AZBN-initiated at 70 °C) addition of perfiuoroalkyl iodides across C=C bonds in cyclic olefins (cyclo-pentene, -hexene, and... 

Cyclic compounds that have a ring of carbon atoms, which are not aromatic, are named using the prefix cyclo. For example, cyclobutane is a cyclic alkane with four carbon atoms. The atoms in the ring are numbered so that the smallest numbers indicate the position of substituents. 

Compound Wpes Mass values Alkanes Alkenes, Mono- cyclo- alkanes Alkynes, Dienes, Cyclo- alkenes Poly- cyclic alicycles Alkanones, Alkanals Alcohols, Alkyl ethers Cyclic alcohols Cyclo- alkanones Aliphat.. acids. Esters, Lactones Alkyl- amines... 

If the C atoms in an alkane are bonded in a row with a formula of the form CH3(CH2)mCH3, the compound, called an unbranched alkane, is named according to the number of C atoms present. All are named with a stem name and the suffix -ane. A cyclic (ring) alkane has the general formula (CH2)m and is designated by the prefix cyclo-. 

Method 3. Reaction of Sodiobis(cyclic dienes) with Inorganic Salts Polymerization of some a,tu-bis(cyclopentadienyl)alkanes with iron salts has been reported (10, II). Reaction of the disodio derivatives of the bis(cyclo-pentadienes) with ferrous chloride in tetrahydrofuran led to polymers and oligomers possessing the ferrocene structure. The polymers were qualitatively described as viscous, brown oils. No quantitative molecular weight data on the polymeric products were obtained. 

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