Secondary carbons

The nitroparaffiiis in which the nitro group is attached to a primary or secondary carbon atom exist in tautomeric forms, for example ... 

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... 

That looks simple and direct don t it If safrole was used as the alkene one would get safrole-azide as product. Just one teensy little reduction away from MDA. Strike also found some azide papers that, with a little work, will get safrole-azide in a totally different way. Strike came across a lot of work where groups were using dinucleophilic addition to get an azide and a halogen added across a double bond. The azide would always go to the beta secondary carbon and the halogen to the primary carbon (just what one would want if safrole was the substrate). 

Interestingly, the allylation of a stabilized carbon nucleophile has been found to be reversible. Complete isomerization of dimethyl methylmalonate, involving bis-allylic C—C bond cleavage, from a secondary carbon 38 to a primary carbon 39 was observed by treatment with a Pd catalyst for 24 h. The C—C bond cleavage of a monoaliylic system proceeds slowly[40]. 

Furthermore, the regioselective hydrogenolysis can be extended to internal allylic systems. In this case, clean differentiation of a tertiary carbon from a secondary carbon in an allylic system is a problem. The regioselectivity in the hydrogenolysis of unsymmetrically substituted internal allylic compounds depends on the nature and size of the substituents. The less substituted alkene 596 was obtained from 595 as the main product, but the selectivity was only... 

On the other hand, the expected alkene 598 was regioselectively formed from the allylic carbonate 597[388]. In these reactions, the hydride from formate preferentially attacks the tertiary carbon rather than the secondary carbon. 

Confoimer with the two methyls of the 5-i-Pr group framing the C4 methyl group. Given in the order secondary carbon, primary carbon for alkyl groups. 

Carbon atoms are classified according to their degree of substitution by other car bons A primary carbon is directly attached to one other carbon Similarly a secondary carbon is directly attached to two other carbons a tertiary carbon to three and a qua ternary carbon to four Alkyl groups are designated as primary secondary or tertiary according to the degree of substitution of the carbon at the potential point of attachment... 

The secondary carbon bears more of the positive charge than does the primary carbon and attack by the nucleophilic bromide ion is faster there Hence the major product is the secondary bromide... 

Secondary carbon (Section 2 13) tached to two other carbons... 

Substituent group Primary carbon Secondary carbon Tertiary carbon Quaternary carbon... 

Freudenberg has obtained one nitrogen-free product, C13H24O, b.p. 215-220°, by the distillation of aconitine or amorphous aconitine with barium hydroxide or zinc dust. He suggests that the fundamental hydrocarbon, C20H33, may contain two five-membered and four six-membered rings, which will include nine secondary carbon atoms. 

Boron tribromide replaces fluonne with bromine on tertiary or secondary carbons however, trifluoromethyl groups are inert in this reaction [70] (equation 57). 

An isopropyl group is a secondary alkyl group. Its point of attachment is to a secondary carbon atom, one that is directly bonded to two other carbons. 

The major application of the Mitsunobu reaction is the conversion of a chiral secondary alcohol 1 into an ester 3 with concomitant inversion of configuration at the secondary carbon center. In a second step the ester can be hydrolyzed to yield the inverted alcohol 4, which is enantiomeric to 1. By using appropriate nucleophiles, alcohols can be converted to other classes of compounds—e.g. azides, amines or ethers. 

Perhaps the earliest report of the replacement of a sulfonate ester attached to a secondary carbon atom in a sugar derivative was that of Helferich (53). Under quite drastic conditions (sodium iodide in acetone, 105°C., 72 hours, sealed system) the 4-mesylate derivative 9 was converted into a crystalline 4-deoxy-4-iodo sugar derivative 10 in 46% yield. Although the position of the iodine atom was established, the configuration at C-4 was not known. 

Primary carbon (1°) Secondary carbon (2°) Tertiary carbon (3°) Quaternary carbon (4C]... 

Figure 16.13 Carbocation intermediates in the nitration of toluene. Ortho and para intermediates are more stable than the meta intermediate because the positive charge is on a tertiary carbon rather than a secondary carbon.

Identify the substitution pattern of the two epoxide carbon atoms—in this case, one carbon is secondary and one is primary. Then recall the guidelines for epoxide cleavages. An epoxide with only primary and secondary carbons usually undergoes cleavage by SN2-like attack of a nucleophile on the less hindered carbon, but an epoxide with a tertiary carbon atom usually undergoes cleavage by backside attack on the more hindered carbon. In this case, an S]sj2 cleavage of the primary C—O epoxide bond will occur. 

Schiffbase, 1147 Scurvy vitamin C and, 772 sec-Butyl group, 84 Second-order reaction, 363 Secondary alcohol, 600 Secondary amine, 917 Secondary carbon, 84 Secondary hydrogen. 85 Secondary structure (protein), 1038-1039... 

Paraformaldehyde/DMSO dissolves cellulose rapidly, with neghgible degradation, and forms the hydoxymethyl (methylol) derivative at Ce [ 140-142]. Therefore, cellulose derivatives at the secondary carbon atoms are easily obtained after (ready) hydrolysis of the methylol residue. Additionally, fresh formaldehyde may add to the methylol group, resulting in longer methylene oxide chains, that can be functionahzed at the terminal OH group, akin to non-ionic, ethylene oxide-based surfactants [143,144]. 

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