Aliphatic carbons

Chlorofluorocarbons (CFCs) Aliphatic carbon compounds containing both chlorine and fluorine atoms. 

The opposite case—reaction of an arenediazonium species with an aliphatic substrate —is possible if a sufficiently acidic C—H bond is present e.g. with /3-keto esters and malonic esters. The reaction mechanism is likely to be of the Sel-type an electrophilic substitution at aliphatic carbon ... 

Recently, various polyesters such as poly(ethylene adipate), poly(tetramethylene adipate), poly(caprolac-tone), and poly(aliphatic carbonate), having terminal hydroxyl groups, were reacted with ACPC to give corresponding macroazoesters and their thermal behaviors were observed by DSC [14]. The block copolymers of these polycondensation polymers with addition polymers such as PSt and PMMA were synthesized [14]. 

Steric factors fall into four main categories 27 (a) The release or occurrence of steric compression due to rehybridization in the transition state where the attacking radical and site of attack are each undergoing rehybridization (from sp1 - sp1 and sp1 - sp respectively for aliphatic carbons - refer Figure 1.6). As a consequence, substituents on the attacking radical are brought closer together while those at the site of attack... 

Compounds acting as coupling components must have a high electron density on the reacting carbon atom. Therefore diazonium ions react only at aliphatic carbon atoms which are activated by electron-withdrawing groups (usually acyl or nitro). There is... 

Reactions such as these are of interest in themselves. Beyond that, one can use the pulse radiolysis experiment as a preparative technique for other species. Thus, the reactions of numerous aliphatic, carbon-centered radicals have been evaluated.22 If one employs a reasonably high concentration of solute, say 0.1-1 M CH3OH, the formation of CH2OH is complete within the electron pulse. Following that, reactions such as the following can be studied ... 

Ross. A. B. Neta, P. Rate Constants for Reactions of Aliphatic Carbon-Centered Radicals in Aqueous Solution U.S. Natl. Bur. of Standards. U.S. Government Printing Office Washington, DC, 1982 NSRDS-NBS70 pp 1-96. 

Using sulfur trioxide a nucleophilic aliphatic carbon and an aromatic nucleus may be connected by a sulfonyl bridge479 (equation 93). Instead of sulfur trioxide, sulfuric acid or chlorosulfonic acid is utilized mostly. The procedures differ mainly by the manner in which the water is eliminated480 e.g., a mixture of sulfuric acid and trifluoroacetic anhydride was used recently481. Similarly to equation 93,3-oxo-2,3-dihydrobenzothiophene 1,1-dioxide is available from acetophenone and chlorosulfonic acid482 (equation 94). 

According to Hatcher and co-authors47 the CP/MAS NMR technique opens up new means of distinguishing between various structural features of aquatic and ter-restric humic materials of rather old origin. They found, for instance that the aliphatic carbons of the humic substances in Holocene sediments, are dominant components suggesting an input of lipid-like materials. 

The Tetrahedral Carbon Atom.—We have thus derived the result that an atom in which only s and p eigenfunctions contribute to bond formation and in which the quantization in polar coordinates is broken can form one, two, three, or four equivalent bonds, which are directed toward the corners of a regular tetrahedron (Fig. 4). This calculation provides the quantum mechanical justification of the chemist s tetrahedral carbon atom, present in diamond and all aliphatic carbon compounds, and for the tetrahedral quadrivalent nitrogen atom, the tetrahedral phosphorus atom, as in phosphonium compounds, the tetrahedral boron atom in B2H6 (involving single-electron bonds), and many other such atoms. 

Sutton, P. W. Dahl, L. F. (1967) "The molecular structure of Co3(CO)g CCH3. A tricyclic organocobalt complex containing a metal-coordinated triply bridging aliphatic carbon atom, J. Am. Chem. Soc. 89,261-268. 

Values of the diamagnetic anisotropy of benzene and other aromatic hydrocarbon molecules are calculated on the basis of the assumption that the p, electrons (one per aromatic carbon atom) are free to move from carbon atom to adjacent carbon atom under the influence of the impressed fields. When combined with the assumed values for the contributions of the other electrons (-2.0X 10-6 for hydrogen, —4.5 X10 c for aromatic carbon, — 6.0XlO-6 for aliphatic carbon) these lead to principal diamagnetic susceptibilities of molecules in approximate agreement with the available experimental data. The diamagnetic anisotropy of graphite is also discussed. 

X10-6 for H bonded to C. The atomic susceptibility of diamond is — 6.00X10-6 we accept this for aliphatic carbon. Now in the aliphatic carbon atom there are four L electrons contributing to the susceptibility in all directions, whereas in the aromatic carbon atom only three remain to be considered, the fourth being involved in the calculation of AK. For aromatic carbon, aside from the pz electron, we accordingly assume the atomic susceptibility... 

Alkenes can be acylated with an acyl halide and a Lewis acid catalyst in what is essentially a Friedel-Crafts reaction at an aliphatic carbon. ° The product can arise by two paths. The initial attack is by the acyl cation RCO (or by the acyl halide free or complexed see 11-14) at the double bond to give a carbocation ... 

The —SO2 group is linked to an aliphatic carbon. Low current yields could be due to hydrogen evolution. TEAOT, Et N tosylate TEAI, Et NI. 

T3C n.m.r. spectra were recorded for the oils produced at 400°, 450°, 550° and 600°C. As the temperature increased the aromatic carbon bands became much more intense compared to the aliphatic carbon bands (see Figure 8). Quantitative estimation of the peak areas was not attempted due to the effect of variations in spin-lattice relaxation times and nuclear Overhauser enhancement with different carbon atoms. Superimposed on the aliphatic carbon bands were sharp lines at 14, 23, 32, 29, and 29.5 ppm, which are due to the a, 8, y, 6, and e-carbons of long aliphatic chains (15). As the temperature increases, these lines... 

These results strongly suggest that in coal structure the covalent bond of benzyl ethers composed of aliphatic carbon and oxygen will be entirely cleaved at temperatures lower than 400°C, and the covalent bond composed of aromatic carbon and oxygen will be considerably decomposed at 450°C, since the unit structure of bituminous coal is considered to be composed of polynucleus of several benzene rings. 

The various symbols have the same meaning as before while the spectral density /csa(A),d(ffla) will be discussed in Section 4. For the moment, let us state that these cross-correlation rates can play a role only if the csa mechanism is important (i.e. for non-aliphatic carbons but certainly not for protons) and if measurements are performed at high... 

The authors work demonstrated that even samples as small as 2.5 mg could be studied yielding data with s/n > 5 1. They further demonstrated for samples with aromatic rings that 60 Hz optimization of the experiment was beneficial and that correlations to aliphatic carbons with smaller LJcc couplings did not experience a serious adverse impact due to the larger optimization but the reverse was not true. Correlations to aromatic carbons were not amenable to optimization biased toward aliphatic carbons (e.g. 40 Hz). Correlations observed in the 1,1-ADEQUATE spectrum of retrorsine (22) are shown on the structure. Complete 1,1-ADEQUATE correlations were not shown for delcosine (23) but the authors noted that the key correlations shown on the structure that were observed in the 1,1-ADEQUATE data were not observed in the H2BC spectrum acquired. The impact of the availability of the 1,1-ADEQUATE data on the Structure Elucidator CASE program is discussed in Section 7. 

Simple tertiary carbocations represent a benchmark against which to compare the reactivity of other a-methyl carbocations. Therefore, it is necessary to deal with complex questions about the mechanism for substitution and elimination reactions at tertiary aliphatic carbon in order to evaluate the rate constant... 

Recent investigations have indicated that the aliphatic carbon fraction, rather than aromatic fraction, was strongly correlated to HOC sorption. For instance, the sorption of phenanthrene was related to nonpolar aliphatic carbon fraction, excluding poly(methylene), but was very strongly correlated with the content of the amorphous nonpolar aliphatic domains including amorphous poly(methylene) (Mao et al. 2002). In other words, the rubbeiy, relatively low-density, and amorphous nonpolar aliphatic carbon domains are excellent for phenanthrene partitioning (Figs. 3 and 4). 

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