Talk:Maleic acid

message: :The section on the maleate ion should be expanded. It should also include an image. The maleate ion has one less hydrogen on one of either of the two ends (since maleic acid is symmetrical, both hydrogens can dissociate equally well). Fuzzform 23:36, 31 October 2007 (UTC)
thread_title: Maleate ion

message: The boiling point is lower than the melting point.  —Preceding unsigned comment added by 218.102.126.247 (talk) 11:08, 8 November 2007 (UTC)
replies: text: That's only because of the decomposition. The compound isn't stable enough to retain its bonds when heated to that temperature range. So in essence, like many organic compounds, it has neither a melting nor boiling point (an intermolecular property) but only a decomposition point (an intramolecular property).  —Preceding unsigned comment added by 137.30.93.201 (talk) 14:42, 10 September 2010 (UTC)
thread_title:  An obvious mistake 

message: Are both carboxyl groups ionised ? this book has "Maleate Ion HOOC-CH=CH-COO-" suggesting only one. If only one - is the one on the left or right as shown ?  Why only one; Is there an internal hydrogen bond that prevents the second carboxyl from ionising ? - Rod57 (talk) 13:43, 14 September 2015 (UTC)
replies: text: Depending on the situation, either one or both of the carboxylic acids can be deprotonated.  Typically "maleate" refers to the ion with a single charge, and when it is a dianion it is referred to as "dibasic" as in this catalog listing: http://www.sigmaaldrich.com/catalog/product/sial/63260?lang=en -- Ed (Edgar181) 14:34, 14 September 2015 (UTC)
thread_title:  What is the charge on the maleate ion 

message: I had been reviewing my old biochemistry text "Biochemistry, 8th edition (1970)" by James M. Orten and Otto W. Neuhaus, on page 266 where it discusses the Citric Acid Cycle, it makes the point that the trans isomer Fumaric acid is produced but the cis isomer Maleic acid is not produced and is "extremely toxic in the animal organism". The citation given is: Orten, J.M. and Smith, A.H.:Proc Soc. Exp. Biol. Med. 36:555, 1937.  — Preceding unsigned comment added by 172.78.56.88 (talk) 23:01, 18 December 2016 (UTC)
thread_title:  Toxicity of Maleic Acid, so it the Food reference in Error ?

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thread_title:  External links modified 

message: Where is this acid found in nature?
There is a reference to the enzyme maleate isomerase used by bacteria for nicotinate metabolism in the text, but no section on if the acid form exists naturally somewhere or if there are important reactions for e.g. metabolism out there that the acid in involved in... Afro~svwiki (talk) 12:49, 10 August 2021 (UTC)
thread_title:  Natural occurencies?