Butyl groups isobutyl

Those derived from isobutane are the 2 methylpropyl (isobutyl) group and the 1 1 dimethylethyl (tert butyl) group Isobutyl is a primary alkyl group because its poten tial point of attachment is to a primary carbon tert Butyl is a tertiary alkyl group because Its potential point of attachment is to a tertiary carbon... 

A loss of 55 is possibly the loss of C4H7 from esters (double hydrogen rearrangement). The loss suggests a butyl or isobutyl group, especially when m/z 56 is also present. 

Unwanted branching of many polymers probably occurs through such isomerizations. PP, formed using cationic polymerization, has methyl, ethyl, w-propyl, w-butyl, isopropyl, gem-dimethyl, isobutyl, and t-butyl groups connected to the main chain. 

Some information is available on other acrylates. N,N-disubstituted acrylamides form isotactic polymers with lithium alkyls in hydrocarbons (12). t-Butylacrylate forms crystallizable polymers with lithium-based catalysts in non-polar solvents (65) whereas the methyl, n-butyl, sec-butyl and isobutyl esters do not. Isopropylacrylate also gives isotactic polymer with lithium compounds in non-polar solvents (34). The inability of n-alkylacrylates to form crystallizable polymers may result from a requirement for a branched alkyl group for stereospecific polymerization. On the other hand lack of crystallizability cannot be taken as definite evidence of a lack of stereoregulating influence, as sometimes quite highly regular polymer fails to crystallize. The butyllithium-initiated polymers of methylmethacrylate for instance cannot be crystallized. The presence of a small amount of more random structure appears to inhibit the crystallization process1. 

Similarly, there are four different kinds of butyl groups. Two (butyl and sec-butyl) are derived from straight-chain butane, and two (isobutyl and tert-butyl) are derived from branched-chain isobutane. The prefixes sec- (for secondary) and tert- (for tertiary) refer to the number of other carbon atoms attached to the branching carbon. There are two other carbons attached to the branch point in a sec-butyl group and three other carbons attached to the branch point in a tert-butyl group. 

Two or more compounds made up of the same number and types of atoms but with different chemical structures are known as isomers. We have already seen the difference between the two isomers -butyl and isobutyl alcohol. These are known as skeletal isomers, since they have different carbon skeletons. There are also positional isomers in which the "functional group" is located at a different position on the carbon skeleton. For example, alpha, beta, and gamma terpineol all have the same arrangement of carbon atoms but with the—OH (hydroxy) group and the double bond in different positions ... 

The names of the secondary-butyl (sec-butyl) and tertiary-butyl (ferf-butyl or f-butyl) groups are based on the degree of alkyl substitution of the carbon atom attached to the main chain. In the, vec-butyl group, the carbon atom bonded to the main chain is secondary (2°), or bonded to two other carbon atoms. In the ferf-butyl group, it is tertiary (3°), or bonded to three other carbon atoms. In both the n-butyl group and the isobutyl group, the carbon atoms bonded to the main chain are primary (1°), bonded to only one other carbon atom. 

We find that there are four butyl groups, two derived from the straight-chain w-butane, and two derived from the branched-chain isobutane. These are given the designations - normal), sec (secondary), iso-, and tert- (tertiary), as shown below. Again the difference between w-bulyl and jec-butyl and between isobutyl and terhbutyl lies in the point of attachment of the alkyl group to the rest of the molecule. 

If the molecule has an easily accessible functional group such as an alcohol, phenol, or amino group, then alkyl chains of various lengths and bulks such as methyl, ethyl, propyl, butyl, isopropyl, isobutyl or terf-butyl can be attached. 

In situ generated allenyltitanium complexes of type 47 are aminated by azodicarboxylic esters and the products may be degraded to a-hydrazino acids (Eq. 59).360 High a-symmetric induction is achieved only when R is a methyl group when it is n-butyl or isobutyl, the enantiomeric excess in the product decreases to 55% and 27%, respectively. 

A facile isomerization of a f-butyl group to an isobutyl group a-bonded to a gold(III) center has been observed in Irans-Au(C I3)2(C4H9)(PPh3) (Scheme 13). The f-butyl to... 

---