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Updated: Aug 16, 2026

Isolating Free Carbenes, their Mixed Dimers and Organic Radicals
Published on: April 19, 2019
2-Methyl-(1Z,3E)-butadiene-1,3,4-tricarboxylic acid, "isoprenetricarboxylic acid"
Mayer B Goren1, Edward A Sokoloski, Henry M Fales
1Laboratory of Applied Mass Spectrometry, National Heart, Lung, and Blood Institute, Bethesda, Maryland 20892, USA.
Abstract:
[reaction: see text] The synthesis of the title compound 7 from ethyl glyoxylate and dimethyl and diethyl beta-methylglutaconate is described along with its physical properties that suggest its inability to assume a cis-dienoid structure due to steric hindrance between the methyl and carboxyl groups.
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Conjugated dienes are compounds characterized by the presence of alternating double and single bonds. In a conjugated system like 1,3-butadiene, the unhybridized 2p orbital on each carbon overlaps continuously, allowing the π electrons to be delocalized across the entire molecule. In contrast, this type of overlap does not occur in cumulated and isolated dienes, such as 2,3-pentadiene and 1,4-pentadiene, respectively. Instead, the π electrons remain localized between the double...
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