Alicyclic carbon atoms

Table VIII. Maximum and Minimum Number of Alicyclic Rings and Alicyclic Carbon Atoms in an Exinite, Vitrinite, and Micrinite...

Tabla IX. Maximum and Minimum Portion of Alicyclic Carbon Atoms of C.i and Ctot for an Exinito, Vitrinito, and Micrinito ... 

Table X shows, in columns 2 and 5, the numbers of CH and CH2 groups per structural unit which can be calculated from the results of Table IV. The values in columns 3 and 4 originate from Table VIII. The data from columns 2 and 5 lead to the values in columns 6 and 7, which give finally the H iicyci/ C iicyci values in columns 8 and 9 of Table X. As expected the micrinite possesses only one value for Haiicyci/Caiicyci (see Table IX). In the case of the exinite, as long as the true number of alicyclic carbon atoms per 10 structural units is not greater than 10-11, all C i icyci atoms can be once substituted, and therefore Haiicyci/Caiicyci can be 1. As soon as the true value of Caiicyci exceeds the value 11, CH2 groups have to be used to complete Caiicyci and therefore Haiicyci/C iicyci increases (this value lies in the extreme case of 57-58 C iicyci atoms per 10 structural units at 1.74). Since the maximum possible number of alicyclic carbon atoms is smaller for exinite than the number of CH2 groups present, all alicyclic C atoms can be unsubstituted, and therefore H iicyci/ Caiicyci can reach the value 2. The situation is somewhat different for the vitrinite. As long as the true number of alicyclic carbon atoms is not greater than 9-10 per 10 structural units, all Caiicyci atoms can be once substituted, and therefore the value 1 for Haiieyei/Caiicyci is possible. If only up to 25-26 alicyclic C atoms are present, all of them can be unsubstituted, and the value...

Oxidation at oliplMlic and alicyclic carbon atoms Oxidation tnvtdving ctirbon-hclcioaiom systenu ... 

Oxidation of alcohol, carbonyl and acid functions, hydroxylation of aliphatic carbon atoms, hydroxylation of alicyclic carbon atoms, oxidation of aromatic carbon atoms, oxidation of carbon-carbon double bonds, oxidation of nitrogen-containing functional groups, oxidation of silicon, phosphorus, arsenic and sulfur, oxidative N-dealkylation, oxidative O- and S-dealkylation, oxidative deamination, other oxidative reactions... 

It should be noted that whilst the benzosultone behaves like a typical aromatic sultone with nucleophilic attack occurring at sulphur, the sultone 73 (3H-2,l-benzoxathiole 1,1-dioxide) behaves like an aliphatic sultone with reaction occurring at the alicyclic carbon atom and so acts as an alkylating agent towards nucleophiles (equation 125)108. 

Cyclic Hydrocarbons. These are structures in which the carbon atoms form a ring instead of an open chain. They are also called carbocyclic or homocyclic compounds. They are divided into two classes alicyclic (or cycloaliphatic) and aromatic compounds. 

Alicyclic Hydrocarbons. These refer to cyclic analogues of aliphatic hydrocarbons and are named accordingly, using the piefix cyclo-." Their properties are similar to their open-chain aliphatic counterparts. Alicyclic hydrocarbons are subdivided into monocyclic (cycloalkanes, cycloalkenes, cycloalkynes, cycloalkadienes, etc.) and polycyclic aliphatic compounds. Monocyclic aliphatic structures having more than 30 carbon atoms in the ring are known, but those containing 5 or 6 carbon atoms are more commonly found in nature [47, p. 28]. 

As pointed out previously, controlled degradation reactions are very difficult with aliphatic or alicyclic hydrocarbons, and most of the relabeling work has been concentrated on aromatic reaction products. Procedures have been extensively described by Pines and co-workers (e.g., 97, 96, also 87, 89-98, 95, 98). For the present purpose, it suffices to note that the 14C contents of the methyl side-chains and the rings in aromatic reaction products are readily estimated by oxidation of the methyl to carboxyl, followed by decarboxylation, while ethyl side-chains may be oxidatively degraded one carbon atom at a time. Radiochemical assays may be made on CO2 either directly in a gas counter, or after conversion to barium carbonate, while other solid degradation intermediates (e.g., benzoic acid or the phthalic acids) may be either assayed directly as solids or burned to CO2. Liquids are best assayed after burning to CO2. 

More than 600 different carotenoids from natural sources have been isolated and characterized. Physical properties and natural functions and actions of carotenoids are determined by their chemical properties, and these properties are defined by their molecular structures. Carotenoids consist of 40 carbon atoms (tetraterpenes) with conjugated double bonds. They consist of eight isoprenoid units j oined in such a manner that the arrangement of isoprenoid units is reversed at the center of the molecule so that the two central methyl groups are in a 1,6-position and the remaining nonterminal methyl groups are in a 1,5-position relationship. They can be acyclic or cyclic (mono- or bi-, alicyclic or aryl). Whereas green leaves contain unesterified hydroxy carotenoids, most carotenoids in ripe fruit are esterified with fatty acids. However, those of a few... 

Radialenes are alicyclic compounds in which all ring carbon atoms are spI. 2-hybridized and carry as many exocyclic double bonds as possible. The general term for the parent... 

Miyamoto and Yamazaki elaborated a general synthetic method to spiro-substituted [l,2,4]triazolo[l,5-c]pyrimi-dines bearing alicyclic rings of different sizes and bearing different (amino and sulfano) substituents in position 5 <1997JHC871>. 13C NMR chemical shifts of the ring carbon atoms of some selected derivatives are compiled in Table 4. 

Cyclopropane is the only planar cis alicyclic compound and the three points lie in the single plane. Its monosubstituted derivative also has a plane of symmetry and the substituted carbon atom is not asymmetric. Let us take the case of cyclopropane-monocarboxylic acid. It has a plane of symmetry shown by the dotted line and hence the molecule is inactive ( xx). 

In semicydic allenic hydrocarbons, one of the terminal allene carbon atoms is part of an alicyclic ring system, as illustrated by the general structure 37 in Scheme 5.3. Numerous hydrocarbons of this type are known, some of them carrying more than one allene group, such as in the case of the conjugated bisallenes 127 and 129 (see Scheme 5.17), and many of them are described in the review literature [2] and will not be repeated here. However, since Chapter 6 on cycloallenes does not treat these derivatives, some new developments in this area will be briefly presented, limited to the two cases in which cydopropane rings form the end groups of the allene moiety, i.e. 246 and 249. 

The fungus assimilated various polyesters. In general, assimilation of aliphatic polyesters by the fungus was better the greater the number of carbon atoms between the ester bonds. Polyesters with side chains were generally less assimilated than without side chains. The fungus also assimilated unsaturated aliphatic polyesters, but hardly assimilated alicyclic and aromatic polyesters. 

Hydrocarbons. Compounds consisting of carbon and hydrogen. The number of such compounds is immense and they may be classified into aliphatic (alicyclic) and aromatic (cyclic) compounds. In the former class, the principal carbon atoms are arranged in chains, while in the latter class they are arranged in one or several rings. Hydrocarbons may also be divided into saturated —in which all four valences of C are satisfied, and unsaturated —in which there are one or more double or triple bonds between carbon atoms... 

From these simple gas products, which correspond to a very large portion of the reacted feed stock, two basic cracking patterns are postulated the first is applicable to aliphatics and alicyclics (I) (thus including paraffins, olefins, and naphthenes), the second to substituted aromatics (II). These two basic patterns are best illustrated by Figures 1 and 2, which show the molar distribution of the principal cracked products according to the number of carbon atoms in the fragments, per 100 moles of feed stock cracked, for selected representatives of the four major hydrocarbon classes, all at 500° C. (see Table II for experimental conditions and product analyses). 

The results of column 3 in Table IX show that in all three macerals more than half of the aliphatic carbon atoms may be present in alicyclic or/and hydroaromatic rings. The micrinite has no range but only one value because even 2 R.i< i > is bigger than the smallest value for (CH2 + CH). There is no doubt that in the case of the micrinite even small errors in the values of the... 

In a similar manner, thiophonol has been condensed with etbyleno oxide itself,1230 with cyclohexene oxide,1230 and more recently with indene oxide.684 The last undergoes addition preferentially at the henscylic epoxide carbon atom Both alicyclic epoxides (Eqs. 663 and 664) are cleaved to 2-phenylthiocycloalkanols possessing fazna-con-figuration. 

A nucleophilic mechanism can be applied in reductions with complex hydrides of highly fluori-nated aliphatic and alicyclic fluoroalkenes with electron-deficient C = C bonds the hydride anion adds as a strong nucleophilic agent to the more electrophilic carbon atom the intermediate anion can then lose a fluoride ion either from the original C = C bond, or from the allylic position finishing an SN2 displacement of the fluorine. Thus, the reductions of vinylic C-F bonds with hydrides proceed by a nucleophilic addition-elimination mechanism. Displacement of fluorine in highly fluorinated aromatic compounds proceeds by the same mechanism ... 

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. 

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