Carboxylate

Carboxylate

A carboxylate anion is an ion with negative chargethat contains the group -COO. It is the conjugate base of a carboxylic acid.

Carboxylic acids dissociate into a carboxylate ion and a positively-charged hydrogen ion (proton) much more readily than alcohols dissociate (into an alkoxide ion and a proton), because the carboxylate ion is more stable: the negative charge that is left behind when a proton leaves the carboxylate group is 'shared' between the two electronegative oxygen atoms in a resonance structure. This delocalization of the electron cloud means that neither of the oxygen atoms is so strongly negatively charged; the positively-charged proton is therefore less readily attracted back to the carboxylate group once it has left. On the other hand, 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. Thus, the carboxylate ion is more stable - this is also why carboxylic acids have a lower pH than alcohols: the higher the number of protons that escape into solution, the lower the pH. [cite book | author= Fox, Marye Anne; Whitesell, James K. | year = 1997 | title = Organic Chemistry | edition = 2| publisher = Jones and Bartlett Publishers | location = Sudbury, Massachusetts| id = ISBN 0-7637-0178-5 ]

Examples

* formate ion, HCOO
* acetate ion, CH3COO

Discussion

References


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Look at other dictionaries:

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  • carboxylate — [kär bäks′ə lāt΄] n. a salt or ester of a carboxylic acid vt. carboxylated, carboxylating to form a carboxylic acid by introducing a carboxyl group into (a compound) carboxylation n …   English World dictionary

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  • carboxylate — n. salt from carboxylic acid (Chemistry) v. add carboxylate (chemical substance) to a compound …   English contemporary dictionary

  • carboxylate — karboksilatas statusas T sritis chemija formulė RCOO(M,R) atitikmenys: angl. carboxylate rus. карбоксилат …   Chemijos terminų aiškinamasis žodynas

  • carboxylate Chemistry — [kα: bɒksɪleɪt] noun a salt or ester of a carboxylic acid. verb add a carboxyl group to (a compound). Derivatives carboxylation noun …   English new terms dictionary

  • Carboxylate ester — A carboxylate ester is an ester where the parent acid is a carboxylic acid.Most typically, the term ester means a carboxylate ester. Although accurately, the acid part of an ester can be any acid.For one, methyl formate is a carboxylate… …   Wikipedia

  • Carboxylate transporter — A carboxylate transporter is a membrane transport protein that transports carboxylate. They are responsible for the reabsorption of filtered carboxylate in renal physiology, resulting in a 100%[1] reabsorption in the proximal tubule. Contents 1… …   Wikipedia

  • Carboxylate reductase — In enzymology, a carboxylate reductase (EC number|1.2.99.6) is an enzyme that catalyzes the chemical reaction:an aldehyde + acceptor + H2O ightleftharpoons a carboxylate + reduced acceptorThe 3 substrates of this enzyme are aldehyde, acceptor,… …   Wikipedia

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