Isobutyl group The

The two alkyl groups attached to aluminum in [(CH3)2CHCH2]2A1H are isobutyl groups. The hydrogen bonded to aluminum is named in a separate word as hydride. Thus, "dibal is a shortened form of the systematic name diisobutylaluminum hydride. 

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. 

Hydrogen-1 NMR. - A proton magnetic resonance spectral study of 0,0 -bis(aryl) isobutyl phosphonates (86) indicated that the P splits the a- and P-protons of the isobutyl group. The apparent coupling constant Jch.ch of a-protons has been found to be different in the two halves of the double doublets, and the two electronic parameters a and F give good predictive models for chemical shift values of a and aromatic protons. 

Isobutane The common name for 2-methylpropane, (CH3)3CH. Isobutyl group The group (CH3)2CHCH2—. 

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... 

Isobutyl group (Section 2 13) The group (CH3)2CHCH2— Isoelectric point (Section 27 3) pH at which the concentration of the zwittenonic form of an amino acid is a maximum At a pH below the isoelectric point the dominant species is a cation At higher pH an anion predominates At the isoelec tnc point the ammo acid has no net charge Isolated diene (Section 10 5) Diene of the type... 

Construct such a model for isotactic polypropylene. Estimate the volume of an isobutyl group on the scale of your model and examine whether interference between successive substituents would occur if this were the R group present. 

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. 

In Step C a dithiane anion was used as a nucleophilic acyl anion equivalent to introduce the C(10)-C(13) isobutyl group. 

Attempts to use the isobutyl group in the carbometalation of alkynes only give rise to hy-drometalated products, but ethyl and n-propyl groups can be successfully transferred from the corresponding dialkylaluminum chlorides. The regioselectivity in these reactions is lower than that for the methyl transfer. Indeed, the reaction mechanism may be different from that of methylalumination [62]. 

Triisobutylaluminum (TIBA) is an effective reducing agent for ketones. However, in most cases only one isobutyl group is available for reduction. Enolization occurs after a rapid reduction involving the first isobutyl group (143,147). For example, an enolate is formed in the reaction of TIBA with cyclohexanone (143) (eq. [31]). 

Figure 10.4 Structure of the self-dimerized V complex on Si02 modeled by DFT. (a) Top view (b) side view. Red vanadium green nitrogen blue oxygen gray Ph ring yellow isobutyl group derived from L-leucine.

The cationic polymerization of vinyl isobutyl ether at —40°C produces stereoregular polymers (structure 5.21). The carbocations of vinyl alkyl ethers are stabilized by the delocalization of p valence electrons in the oxygen atom, and thus these monomers are readily polymerized by cationic initiators. Poly(vinyl isobutyl ether) has a low Tg because of the steric hindrance offered by the isobutyl group. It is used as an adhesive and an impregnating resin. 

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