Secondary alkyl group

Secondary alkyl group Tertiary alkyl group... 

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

Secondary alkyl group (Section 2 13) Structural unit of the type R2CH— m which the point of attachment is to a sec ondary carbon... 

Oxaziridines substituted in the 2-position with primary or secondary alkyl groups undergo decomposition at room temperature. In the course of some weeks, slow decomposition of undiluted compounds occurs, the pattern of which is analogous to that of acidic or alkaline N—O cleavage (Sections 5.08.3.1.3 and 4), Radical attack on a C—H bond in (109) effects N—O cleavage, probably synchronously (57JA5739). In the example presented here, methyl isobutyl ketone and ammonia were isolated after two hour s heating at 150 °C. 

The yields of the dimeric nitroso compounds are good. Thus the aliphatic nitroso compounds which previously were difficult to obtain become readily available. A series of dimeric nitroso compounds with primary and secondary alkyl groups are given in Table III. 

Acidic ether cleavages are typical nucleophilic substitution reactions, either SN1 or Sn2 depending on the structure of the substrate. Ethers with only primary and secondary alkyl groups react by an S 2 mechanism, in which or Br attacks the protonated ether at the less hindered site. This usually results in a selective cleavage into a single alcohol and a single alkyl halide. For example, ethyl isopropyl ether yields exclusively isopropyl alcohol and iodoethane on cleavage by HI because nucleophilic attack by iodide ion occurs at the less hindered primary site rather than at the more hindered secondary site. 

The alkyl group R of certain carboxylic esters can be reduced to RH by treatment with lithium in ethylamine. The reaction is successful when R is a tertiary or a sterically hindered secondary alkyl group. A free-radical mechanism is likely. Similar reduction, also by a free-radical mechanism, has been reported with sodium in HMPA-r-BuOH. In the latter case, tertiary R groups give high yields of RH, but primary and secondary R are converted to a mixture of RH and ROH. Both of these methods provide an indirect method of accomplishing 10-81 for tertiary R. 

Amine (1) was needed to study the stereochemistry of alkylation reactions. The primary alkyl group had best come from an amide or an Imine while the secondary alkyl group must come from an imine. The disconnections may be carried out in any order. 

Nitro groups attached to a primary and secondary alkyl group in a highly basic (pH > 13) medium exist as the nitronate (enolate) anions. These anions must be very difficult to reduce by electron transfer and are surely much more difficult to reduce than water. Since the electrohydrogenation of such nitro compounds to the corresponding amines is veiy efficient at Raney metal cathodes in 0.1 to 0.15 M KOH (or NaOH) aqueous alcohol (pH > 13) (12), as... 

The sequence of the Michael addition of nitroalkanes and denitration provides a general method for conjugate addition of primary and secondary alkyl groups to electron deficient alkenes (Eq. 4.122).168... 

So far triptycenes carrying a secondary alkyl group in the 9-position have been found to give rather unstable atropisomers. To raise the barrier to rotation of the sec-alkyl group, the introduction of substituents in more than one peri position may be helpful the same is true when there is a primary alkyl group at the 9-position (vide infra). 

Summarizing the results related to the barriers to rotation of a secondary alkyl group in the 9-position of a 1-substituted triptycene, we note that the maximum barrier is realized when the peri substituent is chlorine or bromine. Evidently the size of the substituent that gives the maximum barrier to rotation is shifted from that in the 9-rm-alkyl systems. This is considered to be a reflection of the strain in the ground state, which is usually larger in the tertiary alkyl systems than in the secondary, if the same substituent is present in the peri position. 

From the trend in barriers of tertiary and secondary alkyl groups attached to the 9-triptycyl group, the barrier to rotation about a C(9)—C(CH2) bond in 9-ben-zyltriptycenes (116) that carry a peri substituent is expected to be still lower, and it is only about 12 kcal/mol (165). However, if substituents are introduced at another peri position, the barriers are raised considerably. 1,2,3,4,5,6,7,8-... 

Iodide is a good nucleophile. It attacks the least substituted carbon of the oxonlum ion formed in step 1 and displaces an alcohol molecule by S 2 mechanism. Thus, in the cleavage of mixed ethers with two different alkyl groups, the alcohol and alkyl Iodide formed, depend on the nature of alkyl groups. When primary or secondary alkyl groups are present. It Is the lower alkyl group that forms kyl Iodide (Sn2 reaction). 

The inhibition of hydrocarbon autoxidation by zinc dialkyl dithiophosphates was first studied by Kennerly and Patterson (13) and later by Larson (14). In both cases the induction period preceding oxidation of a mineral oil at 155 °C. increased appreciably by adding a zinc dialkyl dithiophosphate. In particular, Larson (14) observed that zinc salts containing secondary alkyl groups were more efficient antioxidants than those containing primary groups. In these papers the inhibition mechanism was discussed only in terms of peroxide decomposition. 

Cyanamide and substituted cyanamides react with alcohols to give pseudoureas. Cyanamide reacts with alcohols in the presence of anhydrous hydrogen chloride, whereas disubstituted cyanamides require slightly more than an equivalent of sodium alkoxide for reaction with the alcohol. (See Tables III and IV.) Catalytic amounts of sodium alkoxides are sufficient to induce the reaction of a cyanamide with primary, secondary, or tertiary alcohols [21] (Eq. 17). When both R groups are secondary alkyl groups, alkaline catalysts... 

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