Chemical reaction which converts between members of a homologous series
In
organic chemistry, a homologation reaction, also known as homologization, is any
chemical reaction that converts the
reactant into the next member of the
homologous series. A homologous series is a group of compounds that differ by a constant unit, generally a
methylene (−CH2−) group. The reactants undergo a homologation when the number of a repeated
structural unit in the molecules is increased. The most common homologation reactions increase the number of methylene (−CH2−) units in
saturated chain within the molecule.[1] For example, the reaction of
aldehydes or
ketones with
diazomethane or
methoxymethylenetriphenylphosphine to give the next homologue in the series.
Arndt–Eistert reaction is a series of chemical reactions designed to convert a carboxylic acid to a higher carboxylic acid homologue (i.e. contains one additional carbon atom)
Kowalski ester homologation, an alternative to the Arndt-Eistert synthesis. Has been used to convert β-amino esters from α-amino esters through an
ynolate intermediate.[2]
Seyferth–Gilbert homologation in which an aldehyde is converted to a terminal alkyne and then hydrolyzed back to an aldehyde.
Some reactions increase the chain length by more than one unit. For example, the
DeMayo reaction can be considered a two-carbon homologation reaction.
^D. Gray, C. Concellon and T. Gallagher (2004). "Kowalski Ester Homologation. Application to the Synthesis of β-Amino Esters". J. Org. Chem.69 (14): 4849–4851.
doi:
10.1021/jo049562h.
PMID15230615.
^Vincent P. Hollander and T. F. Gallagher
PARTIAL SYNTHESIS OF COMPOUNDS RELATED TO ADRENAL CORTICAL HORMONES. VII. DEGRADATION OF THE SIDE CHAIN OF CHOLANIC ACID
J. Biol. Chem., Mar 1946; 162: 549 - 554
Link
^On the Oxidation of 2-Hydroxy-1,4-naphthoquinone Derivatives with Alkaline Potassium Permanganate Samuel C. Hooker
J. Am. Chem. Soc.1936; 58(7); 1174-1179.
doi:
10.1021/ja01298a030
^On the Oxidation of 2-Hydroxy-1,4-naphthoquinone Derivatives with Alkaline Potassium Permanganate. Part II. Compounds with Unsaturated Side Chains Samuel C. Hooker and Al Steyermark
J. Am. Chem. Soc.1936; 58(7); pp 1179 - 1181;
doi:
10.1021/ja01298a031