Carbon atoms numbers

Number of carbon atoms number of double bonds (geometric (cis, trans) isomerism). 

Fig. 2. Dependence of olefin reactivity on its carbon atom number when linear a-olefins are copolymerized with ethylene.

Butene. Commercial production of 1-butene, as well as the manufacture of other linear a-olefins with even carbon atom numbers, is based on the ethylene oligomerization reaction. The reaction can be catalyzed by triethyl aluminum at 180—280°C and 15—30 MPa ( 150 300 atm) pressure (6) or by nickel-based catalysts at 80—120°C and 7—15 MPa pressure (7—9). Another commercially developed method includes ethylene dimerization with the Ziegler dimerization catalysts, (OR) —AIR, where R represents small alkyl groups (10). In addition, several processes are used to manufacture 1-butene from mixed butylene streams in refineries (11) (see BuTYLENEs). 

Halogen derivatives of carbon atoms Number of carbon atoms Chloroacetic acid... 

Note. In these compounds carbon atom number 1 has become chiral. When known, the stereochemistry at this new chiral centre is indicated using the R,S system ([13], Section E). 

Next draw the chair, number it going clockwise, and then put in the up and down positions at the carbon atoms numbered 1 and 2 ... 

The structure of j6-glucose differs from that of a-glucose in the placement of the H atom and the —OH group on carbon atom number 1. 

The six-carbon sugar a-galactose is identical to a-glucose except at carbon atom number 4, where the orientations are different. Draw the molecular structure of a-galactose. Simplify the stmcture by using flat rings rather than the true three-dimensional forms. 

Atom and bond fragments Substructures (atom groups) Substructure environment Number of carbon atoms Number of rings (In polycyclic compounds) Molecular connectivity (extent of branching)... 

Figure 6 Structure and carbon atoms numbering of the 1,3-butadiynyl (ferf-butyl) diphenylsilane molecule. The values of three representative Vch coupling constants are indicated.

This information is normally shown as a superscript (atomic mass) and a subscript (atomic number) to the symbol for the element. Hence 1%C represents the isotope of carbon (atomic number 6) with the atomic mass of 14. In practice the subscript is often omitted because the atomic number is unique to the element that is represented by the appropriate letter (e.g. C for carbon). For simplicity in the spoken form and often in the written form, isotopes are often referred to as carbon-14, phosphorus-32, etc. 

In this model we can pick out the chain of six carbon atoms, numbered 1-6, of which five carry OH groups. So each of these carbon atoms carries the functional group characteristic of alcohols. Note that five of the carbon atoms are chiral. Specifically, carbons 1-5 all possess four distinct substituents and are, therefore, chiral. Finally, note that carbon-1 is linked to two oxygen atoms, one in the hydroxyl group and the one in the ring. 

As shown by Tagawa et al. [74], the alkane excited molecules have a broad absorption band in the visible region with maxima increasing from —430 to —680 nm between C5 and C20 for the -alkanes. This spectrum strongly overlaps with the absorption spectrum of the radical cations with low carbon atom number alkanes the two maxima practically coincide. With increasing carbon atom number, the red shift in the radical cation absorbance is stronger than in the Si molecule absorbance [47,49,84-86]. The decay of the excited molecule absorbance was composed of two components with 0.1- and 1.0-nsec decay times in cyclohexane, and 0.17 and 2.7 nsec in perdeuterocyclohexane [47]. The nature of the faster-decaying component is as yet unclear. 

Figure 7 G(Si) value as a function of the carbon atom numbers in the molecules. When more than one measured value was published, we tried to select the most probable value. Alkanes (1) propane, (2) w-butane, (3) w-pentane, (4) cyclopentane, (5) w-hexane, (6) cyclohexane, (7) w-heptane, (8) cycloheptane, (9) methylcyclohexane, (10) w-octane, (11) cyclooctane, (12) isooctane, (13) w-decane, (14) cyclodecane, (15) cw-decalin, (16) trawx-decalin, (17) w-dodecane, (18) dicyclohexyl, (19) n-hexadecane. (From Refs. 18, 29, 65, 92, 148, and 155.)...

First, one has to identify and name the groups attached to the chain, and number the chain so that the substituent gets the lowest possible number. For example, one of the isomers of pentane is 2-methylbutane, where the parent chain is a four-carbon butane chain, and is numbered starting from the end nearer the substituent group (methyl group). Therefore, the methyl group is indicated as being attached to carbon atom number 2. 

There is a very important feature of this situation, which we can turn to advantage. It will be observed that the set of four methylene carbon atoms, numbers 1, 4, 5, and 8, possess D4h symmetry by themselves and that the set of four carbon atoms in the ring, numbers 2, 3, 6, and 7, also by themselves constitute a set having D4ll symmetry. Furthermore, the atoms in one set are not equivalent symmetrically to any of those in the other. None of the outer atoms is ever interchanged with any of the inner atoms by any symmetry operation. Thus each of these sets can be used separately as the basis for a representation of the group, and if this is done we obtain from each set a representation, r x, which reduces as follows ... 

Commercial production of 1-butene, as well as the manufacture of other linear o-oleJins with even carbon atom numbers, is based on (lie ethylene oligomerization reaction. 

Table I. Optimized carbon-fluorine bond distances in mono-, di-, tri-, tetra-, penta- and hexa-substituted fluorobenzenes calculated at the HF, CASSCF(6,6) and MP2 levels of theory. The basis set used for all optimizations is 6-31G. All distances in A. Fi, F2, etc denote the fluorines connected to carbon atoms number 1, 2, etc. See text for additional CASSCF(8,7), MP4(SDQ), QCISD and DFT results for QH5F.

Fig. 5. Thermodynamic EMF of an in situ reformed alkane cell versus carbon atom number in the alkane molecule. From ref. [10].

Figure 29 Schlegel diagrams with carbon atom numbering for Cgo and C70.

A 6 — c — 12.01 -Carbon - Atomic number Element symbol Atomic weight Element name Noble gases 8A... 

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