Primary carbon, meaning

The fact that we have three olefinic hydrogens means that our compound is a primary olefin, the fact that the other two carbons are both methylene carbons means that our substituent, bromine, is terminal. Thus the only possibility we have is that we are dealing with 4-bromo-1-butene (try to find another isomer that fits ). But this simple molecules has a highly complex proton spectrum, which can only be interpreted completely (exact chemical shift, coupling constants) by spectrum simulation. 

Some serious deviations occur for CH3 groups coupled to primary carbon atoms. In this case especially the tensor component parallel (or nearly parallel) to the C-C bond is overestimated. This also leads to a general overestimation of the mean value of the chemical shift on the end of chains. However, comparing theory and experiment one should keep in mind that the experimental conditions often do not meet the situation of a calculation of an isolated molecule, and the conformations of the molecules under study was unknown. 

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). 

Tlic CH3 CHa CHj - is a primary carbon. Tints the ring must be in the copper lithium complex. This means we need compound A and CH CHjCHal (a permitted starting material). 

A primary carbon atom is attached to only one < other C atoms, and so on. This means 1... 

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. 

Sodium iodide in acetone solution (Finkelstein s reagent ) is most commonly used. By means of this reagent, a nitrate or a sulfonate ester group on a primary carbon atom is replaced by iodine. ... 

The first reason is that sterically there is less hindrance encountered by the approaching nucleophile. The second reason is that primary carbons only very reluctantly form carbonium ions, and so the rate of any competing SN1 reaction is greatly reduced, which means that the presence of any SN2 reaction that occurs will be more readily noticed. 

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. 

This argument means to say that the major fraction of ethylene formed by excited intermediates (in systems which are effectively scavenged so as to eliminate thermal reactions) comes from primary carbon-hydrogen bond insertion by methyne. Small amounts of ethylene may arise from more complex reactions. 

A primary carbon atom Is attached to only one other C atom, a secondary to two other C atoms, and so on. This means there are five types of carbon atom. These names for bits of hydrocarbon framework are more than just useful ways of writing or talking about chemistry. They tell us something fundamental about the molecule and we shall use them when we describe reactions. 

While there are exceptions, most fuel cell developers have gravitated toward a common means of making a catalyst layer. Generally speaking, most catalyst layers employ a structure of platinum particles supported on carbon. The primary carbon particles are approximately 40 nm in diameter... 

A review of the data in Table I reveals that Monarch 880 carbon black is possibly most similar in chemical and physical property to Monarch 1100 except for density. The iodine number, vhich indicates reactivity of vinyl and odier functional groiqis, does not correlate with the results in Table n. Monarch 1100 is twice as dense as Monarch 880, vhich means greater nms per volume. This feature should correlate with tighter packing, possibly due to more interparticle fusion, of die primary carbon black nanoparticles in die aggregates. If diis postulate is valid, the observation that the more dense ag gates yield to breakiqi more efficiendy cannot be eiqilained by die current results. 

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. 

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