11dimethylethyl

11dimethylethyl is the name sometimes encountered for what is more widely known as the tert-butyl group. The standard IUPAC name for this substituent is 1,1-dimethylethyl, and the common synonym is tert-butyl. The term refers to a bulky alkyl substituent attached to a molecule via a central quaternary carbon that is bonded to three methyl groups and the remainder of the molecule.

Structurally, the tert-butyl group has the formula (CH3)3C–. It is derived from tert-butanol (2-methyl-2-propanol) and is attached to a parent structure through the tertiary carbon. The group is highly sterically demanding due to its three methyl substituents surrounding the attachment point, which can influence both reactivity and selectivity in chemical reactions. It is nonpolar and electron-donating through hyperconjugation, contributing to stabilization of adjacent positive charges in some contexts and hindrance in others.

In organic synthesis, the tert-butyl group serves as a versatile protecting group and as a bulky substituent to modulate reactivity. Notable examples include tert-butyloxycarbonyl (Boc) protection of amines, tert-butyl esters (OtBu) for carboxyl groups, and tert-butyldimethylsilyl (TBDMS) derivatives used to protect alcohols in multi-step sequences. Deprotection often employs acidic conditions or other selective reagents that cleave the tert-butyl-related protecting groups, sometimes releasing isobutene as a byproduct.

The term 11dimethylethyl thus denotes a widely used, bulky alkyl substituent whose IUPAC name is 1,1-dimethylethyl and which plays a central role in protecting group chemistry and steric modulation in organic synthesis.