Why does adipic acid give cyclic ketone on heating while glutaric and succinic acid give cyclic anhydride?
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2$\begingroup$ It's different reaction, with Ba(OH)2. I guess you should find more precise source of information. $\endgroup$– MithoronJan 6, 2018 at 20:32
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6$\begingroup$ Seven-rings are notoriously unstable. $\endgroup$– KarlJan 6, 2018 at 21:20
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3$\begingroup$ en.wikipedia.org/wiki/Ketonic_decarboxylation and orgsyn.org/demo.aspx?prep=CV1P0192 $\endgroup$– Nilay GhoshJan 7, 2018 at 4:48
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$\begingroup$ The calcium salt of adipic acid also works. Essentially a Dieckmann cyclization with decarboxylation. Been there. Done it. No metal salt needed with succinic and glutaric acid. $\endgroup$– user55119Mar 23, 2018 at 15:17
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$\begingroup$ @RitwikDas Can you specify the source? Thanks! $\endgroup$– RishiJul 13, 2021 at 12:39
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2 Answers
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According to Blanc Rule for Dibasic Carboxylic acids, A cyclic Ketone is formed unless a five or six membered cyclic acid anhydride can be formed. This rule is valid for 1,4; 1,5; 1,6. dicarboxylic acids
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Because cyclic anhydride formed will be a 7 Member ring compound which is less stable than 5 membered cyclic ketone
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4$\begingroup$ Can you please cite some sources? Also, note that the rings are substituted. Btw, welcome to Chem.SE! $\endgroup$ May 18, 2018 at 8:41