Potassium methoxide is the alkoxide of methanol with the counterionpotassium and is used as a strong base and as a catalyst for transesterification, in particular for the production of biodiesel.
The preparation of potassium methoxide can be achieved on the laboratory scale by the (strongly exothermic) reaction of metallic potassium and methanol upon the release of equimolar amounts of hydrogen.[1]
Kaliummethanolat aus Kalium und Methanol
The reaction of metal hydrides (potassium hydride) with methanol forming potassium methoxide is also possible but less important.
Kaliummethanolat aus Kaliumhydrid und Methanol
The exothermic reaction of potassium hydroxide with methanol leads in an equilibrium reaction to potassium methanolate and water (avoiding formation of highly inflammable hydrogen gas). In a continuous process the formed water must be removed permanently.[2]
Kaliummethanolat aus Kaliumhydroxid und Methanol
The complete removal of the water is critical for the reaction conversion, due to the pronounced hygroscopy of potassium hydroxide, which contains about 10% of water.[3] The significantly higher dissolution rate of potassium hydroxide in methanol compared to sodium hydroxide is advantageous.
On a large scale, potassium methoxide is produced by decomposing potassium amalgam with methanol, which is produced by the chloralkali-electrolysis of potassium chloride by the amalgam process. Impurities of the resulting potassium methoxide in methanol with metallic mercury can be eliminated by ultrafiltration.[4] Solid potassium methoxide is obtained by distilling off the methanol. Because of their simpler production and better handling for chemical purposes solutions of potassium methanolate ( 25 to 32% by weight) are preferably used, which were continuously withdrawn from the amalgam process.
The displacement of the amalgam process by the ecologically and economically superior membrane process for the preparation of the mass chemicals sodium hydroxide and potassium hydroxide will make this standard production process for the production of alkali metal alkoxides in future useless.[5]
Propertiesedit
Potassium methoxide is a white to yellowish, hygroscopic, odorless crystalline powder which reacts violently with water forming potassium hydroxide and methanol. The aqueous solutions obtained are highly basic and have a corrosive effect. The substance is classified as an inflammable solid with a spontaneous ignition temperature of 70 °C.[6]
The human toxicity and ecotoxicity evaluation of potassium methoxide is based on the properties of the decomposition products potassium hydroxide and methanol during hydrolysis in the aqueous medium.[citation needed]
The main application of potassium methoxide is use as basic transesterification catalyst in biodiesel synthesis (as a 25-32% methanolic solution). Triglycerides of vegetable and animal origin are reacted with methanol in the presence of alkali metal methanolates to form the corresponding fatty methyl esters.[9][3]
Potassium methoxide allows a facilitated formation of fatty soaps in comparison to the (lower-priced) sodium methoxide (here potassium salts of the fatty acids from the triglycerides) and higher yields are obtained with potassium methoxide. The optimum conditions for biodiesel production from canola oil are reported as being 1.59% by weight of potassium methoxide, a reaction temperature of 50 °C and a methanol/oil ratio of 4.5: 1. The biodiesel yield is 95.8% with a fatty acid content of 0.75% by weight.[10]
Literatureedit
N.Y. Turova; E.P. Turevskaya; V.G. Kessler; M.I. Yanovskaya, eds. (2002), The Chemistry of Metal Alkoxides, Springer US, doi:10.1007/b113856, ISBN978-0-7923-7521-0
^Chimtek Engineering: Potassium Methylate Production Technology, retrieved 12 August 2015.
^ abJ. Ruwwe (2008), "Metal alkoxides as catalysts for the biodiesel production" (PDF), Chim. Oggi Chem. Today, vol. 26, no. 1, pp. 26–28
^EP 2656905, M. Horn, B. Helpap, M. Thiel, M. Neumann, "Entquickung von Lösungen durch Ultrafiltration", published 2013-10-30, assigned to Evonik Degussa GmbH
^ICF International: Study on EU Implementation of the Minamata Convention on Mercury, retrieved 12 August 2015.
^B.N. Pattanaik (2013), "The advances in processes and catalysts for the production of methyl formate by methanol carbonylation – a review", IJCPT, vol. 3, no. 2, pp. 55–70, ISSN 2277-4807
^US 20140148614, D. Schneider, K.-D. Mohl, M. Schäfer, J. Paschold, J.H. Teles, S. Rittinger, "Process for preparing methyl formate by reaction of methanol with carbon monoxide in the presence of a catalyst system comprising alkali metal formate and alkali metal alkoxide", published 2014-05-29, assigned to BASF SE
^G. Knothe; J. Krahl; J. Van Gerpen, eds. (2010), The Biodiesel Handbook (2nd ed.), AOCS Press, ISBN978-1-893997-62-2
^A. Singh; B. He; J. Thompson; J. Van Gerpen (2006), (PDF), Appl. Eng. Agric., vol. 22, no. 4, pp. 597–600, archived from the original (PDF) on 2015-11-23, retrieved 2017-02-13
December 15, 2023
potassium, methoxide, alkoxide, methanol, with, counterion, potassium, used, strong, base, catalyst, transesterification, particular, production, biodiesel, namesiupac, name, systematic, iupac, name, potassium, methylateidentifierscas, number, hydrogen, error,. Potassium methoxide is the alkoxide of methanol with the counterion potassium and is used as a strong base and as a catalyst for transesterification in particular for the production of biodiesel Potassium methoxide NamesIUPAC name Potassium methoxideSystematic IUPAC name Potassium methylateIdentifiersCAS Number 865 33 8 hydrogen error N3D model JSmol Interactive imageChemSpider 141079ECHA InfoCard 100 011 579EC Number 212 736 1PubChem CID 23664618UNII 45MYQ0GWGBUN number 3206CompTox Dashboard EPA DTXSID1029627InChI InChI 1S CH3O K c1 2 h1H3 q 1 1Key BDAWXSQJJCIFIK UHFFFAOYSA NInChI 1 CH3O K c1 2 h1H3 q 1 1Key BDAWXSQJJCIFIK UHFFFAOYADSMILES K O CPropertiesChemical formula CH3KOMolar mass 70 132HazardsGHS labelling PictogramsSignal word DangerHazard statements H228 H251 H290 H302 H314Precautionary statements P210 P234 P235 P410 P240 P241 P260 P264 P270 P280 P301 P312 P301 P330 P331 P303 P361 P353 P304 P340 P305 P351 P338 P310 P321 P330 P363 P370 P378 P390 P404 P405 P407 P413 P420 P501Except where otherwise noted data are given for materials in their standard state at 25 C 77 F 100 kPa Infobox references Contents 1 Preparation 2 Properties 3 Use 4 Literature 5 See also 6 ReferencesPreparation editThe preparation of potassium methoxide can be achieved on the laboratory scale by the strongly exothermic reaction of metallic potassium and methanol upon the release of equimolar amounts of hydrogen 1 nbsp Kaliummethanolat aus Kalium und MethanolThe reaction of metal hydrides potassium hydride with methanol forming potassium methoxide is also possible but less important nbsp Kaliummethanolat aus Kaliumhydrid und MethanolThe exothermic reaction of potassium hydroxide with methanol leads in an equilibrium reaction to potassium methanolate and water avoiding formation of highly inflammable hydrogen gas In a continuous process the formed water must be removed permanently 2 nbsp Kaliummethanolat aus Kaliumhydroxid und MethanolThe complete removal of the water is critical for the reaction conversion due to the pronounced hygroscopy of potassium hydroxide which contains about 10 of water 3 The significantly higher dissolution rate of potassium hydroxide in methanol compared to sodium hydroxide is advantageous On a large scale potassium methoxide is produced by decomposing potassium amalgam with methanol which is produced by the chloralkali electrolysis of potassium chloride by the amalgam process Impurities of the resulting potassium methoxide in methanol with metallic mercury can be eliminated by ultrafiltration 4 Solid potassium methoxide is obtained by distilling off the methanol Because of their simpler production and better handling for chemical purposes solutions of potassium methanolate 25 to 32 by weight are preferably used which were continuously withdrawn from the amalgam process The displacement of the amalgam process by the ecologically and economically superior membrane process for the preparation of the mass chemicals sodium hydroxide and potassium hydroxide will make this standard production process for the production of alkali metal alkoxides in future useless 5 Properties editPotassium methoxide is a white to yellowish hygroscopic odorless crystalline powder which reacts violently with water forming potassium hydroxide and methanol The aqueous solutions obtained are highly basic and have a corrosive effect The substance is classified as an inflammable solid with a spontaneous ignition temperature of 70 C 6 The human toxicity and ecotoxicity evaluation of potassium methoxide is based on the properties of the decomposition products potassium hydroxide and methanol during hydrolysis in the aqueous medium citation needed Use editThe carbonylation of methanol with carbon monoxide to methyl formate methyl methanoate is catalyzed by strong bases such as potassium methoxide 7 8 The main application of potassium methoxide is use as basic transesterification catalyst in biodiesel synthesis as a 25 32 methanolic solution Triglycerides of vegetable and animal origin are reacted with methanol in the presence of alkali metal methanolates to form the corresponding fatty methyl esters 9 3 Potassium methoxide allows a facilitated formation of fatty soaps in comparison to the lower priced sodium methoxide here potassium salts of the fatty acids from the triglycerides and higher yields are obtained with potassium methoxide The optimum conditions for biodiesel production from canola oil are reported as being 1 59 by weight of potassium methoxide a reaction temperature of 50 C and a methanol oil ratio of 4 5 1 The biodiesel yield is 95 8 with a fatty acid content of 0 75 by weight 10 Literature editN Y Turova E P Turevskaya V G Kessler M I Yanovskaya eds 2002 The Chemistry of Metal Alkoxides Springer US doi 10 1007 b113856 ISBN 978 0 7923 7521 0See also editMethoxideReferences edit A R Ronzio W B Cook 4 Amino 2 6 dimethylpyrimidine Organic Syntheses 24 doi 10 15227 orgsyn 024 0006 Chimtek Engineering Potassium Methylate Production Technology retrieved 12 August 2015 a b J Ruwwe 2008 Metal alkoxides as catalysts for the biodiesel production PDF Chim Oggi Chem Today vol 26 no 1 pp 26 28 EP 2656905 M Horn B Helpap M Thiel M Neumann Entquickung von Losungen durch Ultrafiltration published 2013 10 30 assigned to Evonik Degussa GmbH ICF International Study on EU Implementation of the Minamata Convention on Mercury retrieved 12 August 2015 Evonik Industries GPS Safety Summary Potassium Methylate retrieved 12 August 2015 B N Pattanaik 2013 The advances in processes and catalysts for the production of methyl formate by methanol carbonylation a review IJCPT vol 3 no 2 pp 55 70 ISSN 2277 4807 US 20140148614 D Schneider K D Mohl M Schafer J Paschold J H Teles S Rittinger Process for preparing methyl formate by reaction of methanol with carbon monoxide in the presence of a catalyst system comprising alkali metal formate and alkali metal alkoxide published 2014 05 29 assigned to BASF SE G Knothe J Krahl J Van Gerpen eds 2010 The Biodiesel Handbook 2nd ed AOCS Press ISBN 978 1 893997 62 2 A Singh B He J Thompson J Van Gerpen 2006 Process optimization of biodiesel production using alkaline catalysts PDF Appl Eng Agric vol 22 no 4 pp 597 600 archived from the original PDF on 2015 11 23 retrieved 2017 02 13 Retrieved from https en wikipedia org w index php title Potassium methoxide amp oldid 1159822611, wikipedia, wiki, book, books, library,
