Propargyl group

Propargyl group ( marked in blue ) as part of an organic structure (R = hydrogen atom, alkyl radical, aryl radical, carboxy radical, hydroxy radical, halogen, etc.). Examples:
(a) R = OH: propargyl alcohol , propyn-1-ol or 2-propyn-1-ol;
(b) R = Br: propargyl bromide, 3-bromopropyne or 3-bromo-1-propyne.

The propargyl group is a hydrocarbon residue from the field of organic chemistry . It consists of the unsaturated propyne residue, which contains a triple bond , and the alkyne is homologous to the allyl group .

Are at the propargyl cationic cleavable remains tied, the propargylic created by the demerger. This is mesomerism-stabilized between the boundary structures of the propargyl cation and the propadiene cation. Attacking nucleophiles can react in two positions, creating different products .

Acid-induced cleavage of a hydroxyl group or cleavage of an ether with formation of a propargylic cation.

In order to obtain a substitution in the propargylic position, a Nicholas reaction can be carried out in which the triple bond is protected beforehand by the formation of a cobalt complex.

Protection of the triple bond of the propargyl group by dicobalt hexacarbonyl , which can be obtained from dicobalt octacarbonyl .

Individual evidence

1. ^ Siegfried Hauptmann : Organic Chemistry , 2nd edition, VEB Deutscher Verlag für Grundstoffindindustrie, Leipzig, 1985, p. 257, ISBN 3-342-00280-8 .
2. ^ KM Nicholas, R. Pettit: An alkyne protecting group , in: Tetrahedron Letters 1971 , 37 , 3475-3478. doi : 10.1016 / S0040-4039 (01) 97209-0 .