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== Exemplos de casos estudados ==
[[Ficheiro:Tetrahydrocannabinolicacid.svg|miniatura|Ácido tetrahidrocannabinólico. A descarboxilación deste composto pola calor é esencial para oefectopsicoactivo do [[cánnabis]] fumado, e depende da conversión dun [[enol]] ao grupo cero cando o carbono alfa é protonado.]]
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Sometido a calor, o ácido Δ9-tetrahidrocannabinólico descarboxílase para dar o composto psicoactivo Δ9-[[tetrahidrocannabinol]].<ref>{{cite web|url= http://www.cannabisculture.com/content/2003/01/02/2794|title= Does marijuana have to be heated to become psychoactive?}}</ref> <ref>{{cite journal|url=https://www.researchgate.net/publication/251476768_Decarboxylation_of_D_9-tetrahydrocannabinol_Kinetics_and_molecular_modeling|title=Decarboxylation of Δ9-tetrahydrocannabinol: Kinetics and molecular modeling|journal=Journal of Molecular Structure|volume=987|pages=67|date=February 2011|doi=10.1016/j.molstruc.2010.11.061|last1=Perrotin-Brunel|first1=Helene|last2=Buijs|first2=Wim|last3=Spronsen|first3=Jaap van|last4=Roosmalen|first4=Maaike J.E. van|last5=Peters|first5=Cor J.|last6=Verpoorte|first6=Rob|last7=Witkamp|first7=Geert-Jan|bibcode=2011JMoSt.987...67P}}</ref>
[[Ficheiro:Tetrahydrocannabinolicacid.svg|miniatura|Ácido tetrahidrocannabinólico. The decarboxylation of this compound by heat is essential for the psychoactive effect of smoked [[cannabis]], and depends on conversion of the [[enol]] to a keto group when the alpha carbon is protonated.]]
Upon heating, Δ9-Tetrahydrocannabinolic acid decarboxylates to give the psychoactive compound Δ9-[[Tetrahydrocannabinol]].<ref>{{cite web|url= http://www.cannabisculture.com/content/2003/01/02/2794|title= Does marijuana have to be heated to become psychoactive?}}</ref> When cannabis is heated in vacuum, the decarboxylation of [[tetrahydrocannabinolic acid]] (THCA) appears to follow [[first order kinetics]]. The log fraction of THCA present decreases steadily over time, and the rate of decrease varies according to temperature. At 10-degree increments from 100 to 140 C, half of the THCA is consumed in 30, 11, 6, 3, and 2 minutes; hence the rate constant follows [[Arrhenius' law]], ranging between 10<sup>−8</sup> and 10<sup>−5</sup> in a linear log-log relationship with inverse temperature. However, modelling of decarboxylation of [[salicylic acid]] with a water molecule had suggested an activation barrier of 150 kJ/mol for a single molecule in solvent, much too high for the observed rate. Therefore, it was concluded that this reaction, conducted in the solid phase in plant material with a high fraction of carboxylic acids, follows a pseudo first order kinetics in which a nearby carboxylic acid participates without affecting the observed rate constant. Two transition states corresponding to indirect and direct keto-enol routes are possible, with energies of 93 and 104 kJ/mol. Both intermediates involve protonation of the [[alpha carbon]], disrupting one of the double bonds of the aromatic ring and permitting the beta-keto group (which takes the form of an [[enol]] in THCA and THC) to participate in decarboxylation.<ref>{{cite journal|url=https://www.researchgate.net/publication/251476768_Decarboxylation_of_D_9-tetrahydrocannabinol_Kinetics_and_molecular_modeling|title=Decarboxylation of Δ9-tetrahydrocannabinol: Kinetics and molecular modeling|journal=Journal of Molecular Structure|volume=987|pages=67|date=February 2011|doi=10.1016/j.molstruc.2010.11.061|last1=Perrotin-Brunel|first1=Helene|last2=Buijs|first2=Wim|last3=Spronsen|first3=Jaap van|last4=Roosmalen|first4=Maaike J.E. van|last5=Peters|first5=Cor J.|last6=Verpoorte|first6=Rob|last7=Witkamp|first7=Geert-Jan|bibcode=2011JMoSt.987...67P}}</ref>
InEn beveragesbebidas storedalmacenadas fordurante longlongos periodsperíodos, verypoden smallformarse amountscantidades ofmoipequenas de [[benzenebenceno]] maya formpartir fromde [[benzoicácico acidbenzoico]] by decarboxylationpor catalyzeddescarboxilación bycatalizada thepola presencepresenza ofde [[ascorbicácido acidascórbico]].<ref>{{cite web |url=http://www.cfsan.fda.gov/~dms/benzdata.html |title=Archived copy |accessdate=2008-03-26 |deadurl=yes |archiveurl=https://web.archive.org/web/20080326000150/http://www.cfsan.fda.gov/~dms/benzdata.html |archivedate=2008-03-26 |df= }}</ref>
TheA additionadición ofde catalyticcantidades amountscatalíticas ofde [[cyclohexenoneciclohexenona]] hascataliza beena reporteddescarboxilación to catalyze the decarboxylation ofde [[amino acidsaminoácido]]s.<ref>http://www.erowid.org/archive/rhodium/chemistry/tryptophan.html, Tryptamine from Tryptophan</ref> HoweverPorén, using such catalystsutilizar mayestacatálise alsopode yieldorixinar ana amountformación ofde unwantedprodutos by-productsindesexados.
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== Notas ==
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