Tertiary carbon, meaning

G and H both give an immediate precipitate upon reaction with alcoholic silver nitrate. This means that the bromine is probably attached to a tertiary carbon. 

The slopes of the lines obtained from the Taft correlations of aliphatic primary, secondary and tertiary chlorides obtained at different temperatures by the extrapolation p%2lP%i T IT2 indicate that the positive nature at the carbon reaction center of the C—Cl bond in the transition state increases from a primary to a tertiary carbon atom (Table 8)70. An additional fact is that for each type of alkyl halide, the degree of positive charge at the carbon reaction center tends to decrease as the temperature increases. This means that the pyrolytic eliminations tend to be more concerted and less polar at very high temperatures. These data support Maccoll s theory on the heterolytic character of the alkyl halides pyrol-yses in the gas phase1. 

The two ends of the allylic system are contrasted sterically direct (S>j2) attack is at a primary carbon while allylic (S pO attack is at a tertiary carbon atom so that steric hindrance favours the Sn2 reaction. In addition, the number of substituents on the alkene product means that the S 2 product is nearly always preferred—Sn2 gives a trisubstituted alkene while the S 2 product has a less stable monosubstituted alkene. 

This means that it can be used to build up heavily branched esters and carboxylic acids—the sort that are hard to make by alkylation because of the problems of hindered enolates and unreactive secondary alkyl halides. Heavily substituted acids, where CO2H is attached to a tertiary carbon atom, would be hard to make by any other method. And the Favorskii rearrangement is a key step in this synthesis of the powerful painkiller Pethidine. 

The structure of III shows that a C-H bond, presumably that of the tertiary carbon of the isopentyl substituent, is somehow being replaced with a C-C linkage, a process customarily achieved by means of free radical couplings. However, such a radical, as well as any sort of carbanion, would be unlikely in aqueous phosphoric acid. There seem to be few alternatives left at this point. 

As illustrated in Fig. 20.1, the C-C bond that is broken in the hydrogenolysis of alkyl cyclopropanes is that one between the two least substituted carbon atoms of the ring. With unsymmetrical 1,2-dialkyl-cyclopropanes (1, R iR ) the bond adjacent to the smaller alkyl group is preferentially cleaved. When coupled with the facile cyclopropanation of alkenes, the hydrogenolysis of alkyl cyclopropanes over platinum oxide has served as a useful means of introducing a methyl group onto a tertiary carbon atom as illustrated by the preparation of tert-butyladamantane (3) (Eqn. 20.1) and the 9-methyldecalins, 5 and 6 (Eqn. 20.2). > ... 

One of the most important phenomena of C2-C3 copolymerization is that C3 units may enter the chain with either the head (methylene group) or the tail (tertiary carbon atom) pointing toward the catalyst This means that both vicinal methyl groups and methylene sequences containing an even number of units can occur in the copolymers. 

In branched-chain fatty acids the hydrogen on a tertiary carbon atom can be replaced by hydroxyl by means of alkaline permanganate solution e.g., 2-hydroxy-2-methylpropionic acid, HO—C(CH3)2—C02H, is obtained from isobutyric acid, and 4-methyl-y-valerolactone is obtained from 4-methylvaleric acid.227... 

Cj olefmic components find fewer applications than the C4 compounds. The main applications concern isoamylenes with a tertiary carbon atom, ix. essentially 2-methyl butenes, which produce isoprene by dehydrogenation and Ter Amyl Methyl Ether (TAME) by etherification. The fust conversion is discussed in detail in Section 6. As for the second its value, like that of MTBE, is associated with the antiknock properties of TAME which make it an excellent octane promoter for gasolines. By cracking, the ether can even reproduce isoamylenes. This operation offers one means of separating 2-metbyl butenes and a method that is likely to be more economic than direct extraction to obtain isoprene. 

The vigorous oxidation reaction depicted above will occur with primary and secondary alcohols, but not with tertiary alcohols. This means that the hydroxyl group in menthol must be on the secondary and not the tertiary carbon on the ring ... 

It was found that the macroradicals recorded by ESR spectroscopy usually have the unpaired electron located to a tertiary carbon atom. It means that the chemical bonds splitting preferentially occur to the chemical bonds containing a totally substituted carbon atom, i.e. at the a-methylstyrene structural units, Figure 3.303. 

To see what the prefixes sec- and tert- mean, we must introduce new and important terminology (Fig. 2.34). A primary carbon is a carbon that is attached to only one other carbon atom. A secondary carbon is a carbon attached to two other carbons, and a tertiary carbon is a carbon attached to three other carbons. A quaternary not quarternary) carbon (not shown in Figure 2.34, but we ll see one in a moment) is a carbon that is attached to four other carbons. Thus, the names rcc-butyl and tert-butyl tell you something about the structure. 

We have seen that increasing the substitution around a radical is a stabilizing influence. We called this an inductive ect, which means that the alkyl substituent donates electron density to the electron-deficient radical center. We often say that inductive effects are through-bond effects, as if the bond were a wire of sorts through which electron density can be transferred. Let s consider the rm-butyl radical. It is very nearly planar, and it has a half-filled 2p orbital on the tertiary carbon. 

The terms primary- secondary, tertiary, and quaternary are routinely used in organic chemistry, and their meanings need to become second nature. For example, it we were to say, "Citric acid is a tertiary alcohol," we would mean that it has an alcohol functional group (-OH) bonded to a carbon atom that is itself bonded to three other carbons. (These other carbons may in turn connect to other functional groups). 

To set up the calculation, we specify initial isotopic compositions for the fluid and calcite. We choose a value of —13 %c for r) 18 Os mow of the Lyons fluid, reflecting Tertiary rainfall in the region, and set the calcite composition to +11 %o, the mean of the measured values (Fig. 25.4). We further set S13C pi)B for the fluid to — 12 %o. We do not specify an initial carbon composition for the calcite, so the model sets this value to — 11 %c, in isotopic equilibrium with the fluid. Again, this value is near the mean of the measurements. 

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