Secondary carbon, meaning

The literature states that if one uses ice cold, concentrated sulfuric acid on a terminal alkene (a.k.a. allylbenzene) an alcohol (OH) intermediate will form Markovnikoviy on the secondary carbon (don t ask). What does this mean Let s take an example. Say one has some elemi oil and wants that elemicin that is in it. What one can do is chili, say, 500mLs of the oil to freezing and do the same for about 100-200mLs of concentrated sulfuric acid (at least 90% cone.). Next, one just mixes the two together for about 5 min. What will happen is that the cold H2SO4 will make a hydrogen... 

Let us now synthesize the molecule I-a using procedure I-3a whereby we will add a 3-carbon molecule to a 2-carbon molecule. Remember for procedure I-3a the stipulation that one of the alkyl halides added must be a primary halide. Looking at the two carbons which are to be joined we can readily see that CH,CH, — is a primary carbon, while (CH3 )a CH— is a secondary carbon. This means that for the synthesis of I-a, the isopropyl group must be in the Form of the CuLi complex. Thus we need compound A and CHjCHjI (a permitted starting material). 

Notice that an iso group has a methyl group on the next-to-the-last carbon in the chain. Notice also that all isoalkyl compounds have the substituent (OH, Cl, NH2, etc.) on a primary carbon, except for isopropyl, which has the substituent on a secondary carbon. The isopropyl group could have been called a yec-propyl group. Either name would have been appropriate because the group has an iso structural unit and a hydrogen has been removed from a secondary carbon. Chemists decided to call it isopropyl, however, which means that sec is used only for yec-butyl. 

The value k n decreases for normal alkanes with increasing n. This effect reflects the growth of steric barriers as a result of the hydrophobic molecule rolling itself up into a coil . For n-octane, almost half the carbon atoms do not participate in the reaction. It should be noted that the rate constant of the oxidation remains practically unchanged despite the increase of the number of carbon atoms from pentane to octane. This may mean that only the C-H bonds of the primary and secondary carbon atoms from the hydrocarbon are reactive, i.e., ti)- and CO-1-carbon atoms. If this is so, then steric factors in the alkane oxidation by platinum complexes produce the same effect as they do in the selective oxidation under the action of monooxygenase with participation of cytochrome P450 and methane monooxygenase. 

More energy must be supplied to produce a primary alkyl radical (the propyl radical) from propane than is required to produce a secondary carbon radical (the isopropyl radical) from the same compound. This must mean that the primary radical has absorbed more energy and thus has greater potential energy. Because the relative stability of a chemical species is inversely related to its potential energy, the secondary radical must be the more stable radical (Fig. 10.1a). In fact, the secondary isopropyl radical is more stable than the primary propyl radical by 10 kJ mol ... 

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. 

Finally the aminoquinoline bearing a primary amine at the terminal carbon atom of the side chain is itself an effective antimalarial drug. Ring opening of 2-methyltetrahydrofuran by bromine gives the dibromide, 99. The primary halide is sufficiently less hindered so that reaction with potassium phthalimide affords exclusively the product of displacement of that halogen (100). Alkylation of the aminoquinoline with lOO affords the secondary amine, 101. Removal of the phthalimide group by means of hydrazine yields primaquine (102). ... 

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). 

One further difference between the tissues should be noted briefly—that of turnover—which holds implications for the nature of the isotopic signal recorded and its interpretation. Bone is constantly resorbed and reformed during life, i.e., it turns over , whereas enamel and dentine do not, although secondary dentine can be later accreted. Enamel and dentine form during a discrete period in the individual s life. This means that carbon isotope dietary signals in bone, for both collagen and apatite, reflect diet integrated over years, whereas those in enamel and dentine increments reflect diet at time of formation. 

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