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Title NMR spectroscopic and densimetric study of reaction kinetics of formaldehyde polymer formation in water, deuterium oxide, and methanol
Creator/Author Hahnenstein, I. ; Albert, M. ; Hasse, H. ; Kreiter, C.G. ; Maurer, G. (Univ. Kaiserslautern (Germany))
Publication Date1995 Feb 01
OSTI IdentifierOSTI ID: 6493074
Other Number(s)ISSN0888-5885; CODEN: IECRED
Resource TypeJournal Article
Resource RelationIndustrial and Engineering Chemistry Research ; Vol/Issue: 34:2
Subject400105 -- Separation Procedures; FORMALDEHYDE-- SEPARATION PROCESSES; AQUEOUS SOLUTIONS;DESIGN;DISSOLUTION;GLYCOLS;HEAVY WATER;MATERIALS HANDLING;MEASURING METHODS;METHANOL;REACTION KINETICS;SEPARATION EQUIPMENT;SOLVENT PROPERTIES;SYNTHESIS
Related SubjectALCOHOLS;ALDEHYDES;DISPERSIONS;HYDROGEN COMPOUNDS;HYDROXY COMPOUNDS;KINETICS;MIXTURES;ORGANIC COMPOUNDS;OXYGEN COMPOUNDS;SOLUTIONS;WATER
Description/Abstract In industrial processes, formaldehyde is mainly handled in aqueous solutions, which often contain methanol.^In these solutions, formaldehyde forms predominantly adducts with the solvents.^In aqueous solutions, methylene glycol and poly(oxymethylene) glycols are formed, in methanolic solutions hemiformal and poly(oxymethylene) hemiformals.^As both the formation of poly(oxymethylene) glycol and of poly(oxymethylene) hemiformal are slow compared to typical residence times in separation equipment, reliable information on kinetics of these reactions is essential for process design.^Two independent methods were applied to obtain this information: NMR spectroscopy and high-resolution densimetry.^The experiments were carried out at temperatures between 273 and 334 K and pH between 2 and 9. Both for poly(oxymethylene) glycol formation and poly(oxymethylene) hemiformal formation, the minimal reaction rate occurs between pH 3 and 5. At 293 K, the inverse rate constant 1/k at this minimum is about 6 min for poly(oxymethylene) glycol formation and about 110 h for poly(oxymethylene) hemiformal formation.^The rate constants determined with NMR spectroscopy and densimetry generally agree well.^Previously reported discrepancies between results from both methods are explained by the fact that rate constants of poly(oxymethylene) glycol formation depend strongly on the solvent water or deuterium oxide.^Reaction kinetics of poly(oxymethylene) glycol and poly(oxymethylene) hemiformal formation in the mixed-solvent system with water and methanol predicted from results obtained in the single-solvent systems are in good agreement with experimental data.
Country of PublicationUnited States
LanguageEnglish
FormatPages: 440-450
System Entry Date2001 May 13

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