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Methine group
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<h2 id="overlapping-methines">Overlapping methines</h2> <p>Two or more methine bridges can overlap, forming a chain or ring of carbon atoms connected by alternating single and double bonds, as in <a href="/facts/Piperylene/3cAzSzVG">piperylene</a> H2C=CH−CH=CH−CH3, or the compound </p> <p>Every carbon atom in this molecule is a methine carbon atom, except for three; two that are attached to the two <a href="/facts/Nitrogen/Nf1QpGDz">nitrogen</a> atoms and not to any hydrogen atoms, and the carbon attached to the nitrogen atom, which is attached to two hydrogen atoms (far right). There is a five-carbon-atom poly-methine chain in the center of this molecule. </p><p>Chains of alternating single and double bonds often form <a href="/facts/Conjugated_system/Ddx9qzox">conjugated systems</a>. When closed, as in <a href="/facts/Benzene/Fguue7nr">benzene</a> (=CH−CH=)3, they often give <a href="/facts/Aromatic_(chemistry)/wK0DzRY6">aromatic</a> character to the compound. </p> <h2 id="see-also">See also</h2> <ul><li><a href="/facts/Methyl_group/fkM97EMD">Methyl group</a> −CH3</li> <li><a href="/facts/Methylene_group/sdGv7zMu">Methylene group</a> or methylidene =CH2</li> <li><a href="/facts/Methylene_bridge/t3lvUJuT">Methylene bridge</a> or methanediyl −CH2−</li> <li>Methanetriyl group >CH−</li> <li>Methylylidyne group ≡C−</li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>"Methanylylidene group". Chemical Entities of Biological Interest (ChEBI) database. 2007. Retrieved 2015-03-05. <a href="http://www.ebi.ac.uk/chebi/searchId.do;459B480BAF25AAC3CD9F2B5C3C3A9A07?chebiId=CHEBI:29432" target="_blank">http://www.ebi.ac.uk/chebi/searchId.do;459B480BAF25AAC3CD9F2B5C3C3A9A07?chebiId=CHEBI:29432</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>(2007) Methanetriyl group in the Chemical Entities of Biological Interest (ChEBI) database. Accessed on 2015-03-05. <a href="http://www.ebi.ac.uk/chebi/searchId.do;58A938AD0980FE8C9FAC6FF7D03B7F51?chebiId=CHEBI:29433" target="_blank">http://www.ebi.ac.uk/chebi/searchId.do;58A938AD0980FE8C9FAC6FF7D03B7F51?chebiId=CHEBI:29433</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> </ol>