Karboksilat: Perbedaan antara revisi
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[[File:Carboxylate-resonance-hybrid.png|thumb|255px|Ion karboksilat]]
[[File:Acrylate-ion-3D-balls.png|thumb|Ion akrilat]]
Suatu '''karboksilat''' adalah suatu [[Garam (kimia)|garam]] atau [[ester]] dari [[asam karboksilat]].
''Garam karboksilat'' memiliki rumus umum M(RCOO)<sub>''n''</sub>, dengan M adalah logam dan ''n'' adalah 1, 2,...; ''ester karboksilat'' memiliki rumus umum RCOOR′. R dan R′ adalah gugus organik; R′ ≠ H.
Suatu '''ion karboksilat''' adalah [[basa konjugat]] dari asam karboksilat, RCOO<sup>−</sup>. Ia adalah [[ion]] dengan [[muatan negatif]].
== Resonance stabilization of the carboxylate ion==
Carboxylic acids easily dissociate into a carboxylate anion and a positively charged hydrogen ion (proton), much more readily than alcohols do (into an [[alkoxide]] ion and a proton), because the carboxylate ion is stabilized by [[Resonance (chemistry)|resonance]]. The negative charge that is left after [[deprotonation]] of the carboxyl group is delocalized between the two [[electronegative]] oxygen atoms in a resonance structure.
:[[File:Carboxylate-resonance-2D.png|400px|Equivalence of the resonance forms the delocalised form of a general carboxylate anion]]
This [[delocalization]] of the electron cloud means that both of the oxygen atoms are less strongly negatively charged; the positive proton is therefore less strongly attracted back to the carboxylate group once it has left; hence, the carboxylate ion is more stable. In contrast, an alkoxide ion, once formed, would have a strong negative charge on the oxygen atom, which would make it difficult for the proton to escape. Carboxylic acids thus have a lower [[pH]] than alcohols: the higher the number of protons in solution, the lower the pH.<ref>{{cite book | last1= Fox|first1= Marye Anne|last2= Whitesell|first2= James K. | year = 1997 | title = Organic Chemistry | edition = 2nd| publisher = Jones and Bartlett Publishers | location = Sudbury, MA| isbn = 0-7637-0178-5 }}</ref>
==Examples==
* [[Formate]] ion, HCOO<sup>−</sup>
* [[Acetate]] ion, CH<sub>3</sub>COO<sup>−</sup>
* [[Lactic acid|Lactate]] ion, CH<sub>3</sub>CH(OH)COO<sup>−</sup>
* [[Oxalate]] ion, {{chem|(COO)|2|2−}}
* [[Citrate]] ion, {{chem|C|3|H|5|O(COO)|3|3−}}
==Referensi==
{{Reflist}}
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