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1,2-disubstituted Cycloalkene undergoing syn and anti addition. Syn addition is the addition of two substituents to the same side (or face) of a double bond or triple bond, resulting in a decrease in bond order but an increase in number of substituents. [3] Generally the substrate will be an alkene or alkyne.
Another example of this is the relationship between oleic acid and elaidic acid; oleic acid, the cis isomer, has a melting point of 13.4 °C, making it a liquid at room temperature, while the trans isomer, elaidic acid, has the much higher melting point of 43 °C, due to the straighter trans isomer being able to pack more tightly, and is solid ...
See: cis–trans isomerism. cis (left) and trans (right) configured double bond in maleic acid and fumaric acid. cis (left) and trans (right) isomerism in a ring system. The descriptors cis (Latin, on this side of) [2] and trans (Latin, over, beyond) [3] are used in various contexts for the description of chemical configurations: [4] [5]
Fumaric acid or trans-butenedioic acid is an organic compound with the formula HO 2 CCH=CHCO 2 H. A white solid, fumaric acid occurs widely in nature. It has a fruit-like taste and has been used as a food additive. Its E number is E297. [3] The salts and esters are known as fumarates. Fumarate can also refer to the C 4 H 2 O 2− 4 ion (in ...
Maleate isomerase can be used to produce fumaric acid, an important building block material for polymerization and esterification reactions, from the isomerization of maleic acid. [7] Maleic acid is produced from maleic anhydride. [7] Maleic acid can also be converted into fumaric acid by thermal or catalytic cis–trans isomerization.
Alkyne hydrogenation is stereospecific, occurring via syn addition to give the cis-alkene. [4] For example the hydrogenation of acetylenedicarboxylic acid using Lindlar catalyst gives maleic acid rather than fumaric acid. An example of commercial use is the organic synthesis of vitamin A which involves an alkyne reduction with the Lindlar catalyst.
The prefix endo is reserved for the isomer with the substituent located closest, or "syn", to the longest bridge. The prefix exo is reserved for the isomer with the substituent located farthest, or "anti", to the longest bridge. Here "longest" and "shortest" refer to the number of atoms that comprise the bridge.
When the single bond between the two centres is free to rotate, cis/trans descriptors become invalid. Two widely accepted prefixes used to distinguish diastereomers on sp³-hybridised bonds in an open-chain molecule are syn and anti. Masamune proposed the descriptors which work even if the groups are not attached to adjacent carbon atoms.