DOCSLIB.ORG

Biuret—A Crucial Reaction Intermediate for Understanding Urea Pyrolysis to Form Carbon Nitrides: Crystal‐Structure Elucidati

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Biuret—A Crucial Reaction Intermediate for Understanding Urea Pyrolysis to Form Carbon Nitrides: Crystal‐Structure Elucidati Full Paper Chemistry—A European Journal doi.org/10.1002/chem.202001396 & Structure Elucidation |Hot Paper| Biuret—A Crucial Reaction Intermediate for Understanding Urea Pyrolysis To Form Carbon Nitrides:Crystal-Structure Elucidation and In Situ Diffractometric, Vibrational and Thermal Characterisation Peter Gross and Henning A. Hçppe*[a] Abstract: The crystal structure of biuret was elucidated by mass reveal that the concentration of reactive gases at the means of XRD analysisofsingle crystalsgrown through slow interfacetothe condensed sample residues is acrucial pa- evaporation from asolution in ethanol. It crystallises in its rameter for the prevailing decompositionpathway.Taking own structure type in space group C2/c (a =15.4135(8) , these findings into consideration, astudy on the optimisa- b=6.6042(3) , c=9.3055(4) , Z =8). Biuret decomposition tion of carbon nitride synthesis from urea on the gram scale, was studied in situ by means of temperature-programmed with standard solid-state laboratory techniques, is presented. powder XRD and FTIR spectroscopy,toidentify aco-crystal- Finally,aserendipitously encountered self-coating of the cru- line biuret–cyanuric acidphase as apreviously unrecognised cible inner walls by graphite during repeatedsynthetic reaction intermediate. Extensive thermogravimetric studies cycles, which prove to be highly beneficial for the obtained of varying cruciblegeometry,heatingrate and initial sample yields,isreported. Introduction from diesel engines,[10] and by materials scientists, on the other hand,[11] due to the recent discovery[12] of urea as precursor to [13] Despite its simple constitution,urea(NH2C(O)NH2)has kept sci- carbon nitride materials. As often happens, one man’s meat entists of various disciplines busy over the last four centuries.[1] is another man’s poison: although solid by-products of urea Its exploration has triggered some of the most pivotaldiscus- pyrolysis are one of many challenges for the implementation sions in the historyofscience, including Prout’s hypothesis,[2] of mobile SCR technologies,[14,15] the sum of which were apar- the Vitalism debate[3] or the theory of metabolic cycles,[4] many tial motivation for what, in 2015, came to light as the so-called of which revolve around the nature of urea formation/degrada- dieselemissions scandals,[16] carbon nitrides are heavily re- tion. In particular,the presumably simple, dry and uncatalysed searched as potentialsuperhard materials,[17] novel semicon- pyrolysis of urea “largelyremains amystery and achallenge to ductors,[18] luminescent materials,[19,20] catalysts and catalyst investigators”,[5] to date. In addition to these persisting funda- substrates,[21] materials for photocatalytic water splitting[22] and mental questionsofmolecular chemistry,renewed exploration because of fundamentalquestionsofstructural chemistry.[23–25] of this topic in recent years has been driven by engineers and Therefore, abetter understanding of urea pyrolysis remains a catalysis chemists, on one hand,[6–9] due to the increasing use crucial challenge for scientists from ahuge variety of disci- of urea as areductant for the selective catalytic reduction plines. (SCR) of nitrous oxidesinthe after-treatment of exhaust gases To shine some light onto urea pyrolysis, many thermogravi- metric and calorimetric studies have been conducted, often in combination with the analysisofevolved gases and/or pyroly- [a] P. Gross, Prof. Dr.H.A.Hçppe Lehrstuhl fürFestkçrperchemie, UniversitätAugsburg sis residues by meansofvibrational spectroscopy,mass spec- Universitätsstr.1,86159 Augsburg (Germany) trometry or chromatography,aswell as thermochemical mod- E-mail:[email protected] elling of the decompositionreaction.[7,26–40] Severalstudies ex- Homepage:https://www.ak-hoeppe.de plicitly reveal the distinct influence of pyrolysis parameters, Supporting information and the ORCID identification number(s) for the au- such as heating rate, initial sample mass and crucible shape on thor(s) of this article can be found under: https://doi.org/10.1002/chem.202001396.Itcontains further figuresillustrat- decomposition temperature,total mass loss and pyrolysis resi- ing powder diffractionpatterns, XPS spectra, as well as FTIR spectra and dues formed.[5,9, 41,42] Thismight be traced back to the complex tables comparing vibrational frequencies. mix of different reaction products and intermediates during 2020 The Authors. Published by Wiley-VCH GmbH. This is an open access urea pyrolysis (the specific compositionisdetermined by the article under the terms of Creative Commons Attribution NonCommercial exact pyrolysis parameters), many of which can furtherreact License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial with each other to form different intermediates. Among them, purposes. ammonia,cyanic acid, carbon dioxide, water,biuret Chem. Eur.J.2020, 26,14366 –14376 14366 2020 The Authors. Published by Wiley-VCH GmbH Full Paper Chemistry—A European Journal doi.org/10.1002/chem.202001396 (H2NC(O)NHC(O)NH2), triuret (H2N(C(O)NH)2C(O)NH2), cyanuric for complementary structural in situ methods, like diffraction [46] acid (H3[C3N3O3]), ammelide (H2[C3N3O2(NH2)]), ammeline or spectroscopy on the solids”. Astonishingly,todate, nei- (H[C3N3O(NH2)2]), melamine ([C3N3(NH2)3]),melam ther spectroscopic nor diffractometriccharacterisation tech- ([C3N3(NH2)2]NH[C3N3(NH2)2]), melem [C6N7(NH2)3]) and melon niqueshave been used to study the pyrolysis of urea andits ([C6N7(NH2)(NH)]n,the last of which is often somewhat mis- decomposition products in situ. In particular,the absence of named graphitic carbon nitride (g-C3N4)throughoutthe litera- diffraction studies is striking,especially with regard to the crys- ture,[24] have been found. All of them have been known since tallographic breakthroughs historically achieved with urea and the pioneering works of Berzelius,[43] Liebig[44] and Wçhler,[45] its decomposition products.[47] One reason for the lack of in and all contribute to the complexity of this pyrolysis with their situ probing of urea, althoughthis does not hold for its de- individual kinetics of formation and decomposition in often composition products, might be the complications linked with overlapping temperature regimes. The thermaldecomposition its melting and evaporation,[48] which we have also encoun- path of urea, as generally established in literature, can be tered during our preliminarystudies and that have prevented broken down into the simplified reaction steps given in Equa- us from conducting in situ powder XRD andFTIR measure- tions (1)–(15): mentsofurea. Furthermore, to the best of our knowledge, no study on the crystal structure of water-free biuret (the simplest T 133 Curea NH OCN m Ð 4ð Þm urea decomposition product already described by Wiedemann 1 [49] NH4 OCN m NH3 g HOCN g ð Þ over 170 years ago )has been published, although the crystal ð Þ ! ð Þ þ ð Þ structures of biurethydrate[50,51] and severalother crystal struc- HNCO [52–57] T 150 Curea þ biuret 2 tures containing biuret molecules have been elucidated. m ! ð Þ We therefore decided to contributeour attempt to solve this T 160 Cbiuret uream HOCN g 3 ! þ ð Þ ð Þ ongoing interdisciplinary chemical conundrum by reporting on our structuraland vibrational characterisationofbiuret, as well T 160 C3HNCO cyanuric acid 4 ! ð Þ as in situ powder XRD andFTIR measurements during its ther- HNCO mal decomposition. Furthermore, we present acomprehensive T 160 Cbiuret þ triuret 5 ! ð Þ thermogravimetric study on biuret, varying heatingrate, initial HNCO T 160 Cbiuret þ cyanuricacid 6 mass, crucibleform andatmosphere over alarge parameter NH!3 ð Þ À range.Finally,weput all lessons learnedinto use by optimising 2HNCO T 160 Curea þ ammelide 7 H O the yield of agram-scale synthesis of melon directly from urea. À 2 ! ð Þ T 190 Ctriuret cyanuricacid 8 NH À !3 ð Þ HNCO T 190 Cbiuret þ ammelide 9 Results H O À 2! ð Þ Crystalstructure of biuret T 250 Ccyanuricacid 3HNCO 10 ! ð Þ Biuret crystallises in anew structure type in the monoclinic NH3 T 250 Cammelide þ ammeline 11 H O space group C2/c (no. 15) with eight molecules per unit cell, as À 2! ð Þ NH3 depictedinFigure 1. Relevantparameters of the crystal-struc- T 250 Cammeline þ melamine 12 H O À 2! ð Þ ture refinement are given in Table 1. All atoms are situated on general positions. The biuret moiety shows that the trans con- T 350 C2melamine melam 13 NH À !3 ð Þ figuration exclusively is almost perfectly flat (largest torsion T 350 C2melam melem 14 angle:38)and oriented either parallel to (19 7 11)orto(19 7¯ NH3 ð Þ À ! 11). The averaged interatomic distances for C O(1.24 ), C Ni À À T 350 C n melem melon 15 n NH (1.38 ,imide N) and C Na (1.32 ,amide N) correspond very À !3 ð Þ À well to the values found in other biuret-containing crystal It should be noted thatthese reaction steps, as well as the structures and to the sum of the ionic radii (Table 2).[58] The temperature ranges reported throughout the literature, might molecule features one intramolecular hydrogen bond between vary,depending on the theoretical and experimentalmethods one carbonyl and one amide group (O Hdistance:1.92 ), as À and parameters chosen. Only the first two steps, that is, the well as two intermolecular hydrogen bondsbetween amide meltingand evaporation of urea [Eq. (1)],aswell as the subse- and carbonyl groups towards each of the two adjacent, copla- quent formation of biuret [Eq. (2)],are agreedupon in all stud- nar biuret molecules,forming two sets of skew ribbons ubiqui- [39] ies, with afew notableexceptions. The challenge of under- tous in the crystal chemistry of ureas (Figure 1b).[51,59–62] The standing the reactionpathway of urea decompositionmight ribbonswithin aset are stackedantiparallel offset with ainter- therefore be simplified, to acertain degree, to the problem of ribbon distance of about 3.3 ,roughly corresponding to the biuret decomposition. sum of the van der Waals radii of N/O and C.
Load more

Recommended publications
  • Methodologies for Food Fraud
    Food Fraud Guide Methodologies for Food Fraud Tips for robust experimental results Executive summary Knowing that food fraud scandals often drive public awareness and regulatory changes, the goal of this paper is to present analytical techniques and experimental methodologies, and introduce multivariate statistics and sample class prediction as it relates to food adulteration. Some approaches such as molecular spectroscopy tend to be less expensive, and a few of these instruments have been miniaturized to the point where they can be field-deployed. Spectroscopic instruments are useful in fingerprinting food because small changes in a sample’s spectral profile can be detected with the latest technology, assuming appropriate data normalization techniques are applied. Similarly, the use of both unit- and high-resolution-based mass spectrometry (MS) can be important in food fraud testing because they can fingerprint food based on the pattern of discrete compounds they detect. While other techniques such as inductively coupled plasma mass spectrometry (ICP/MS) and inductively coupled plasma optical emission spectrometry (ICP/OES) have proven adept at identifying geographic origin based on trace element analysis. Genomic testing can accurately identify fish DNA, even from processed samples. From a methodological perspective, nontargeted approaches have proven effective in fingerprinting samples. The advent of inexpensive computer workstations and statistical software has made it possible to link nontargeted workflows with multivariate statistical analysis to extract useful information from analytical data. Until recently, these approaches have been too expensive or complex for researchers to perform by themselves; instead, the data had been handed over to dedicated statisticians or never fully investigated.
    [Show full text]
  • USP Roundtable for DS Protein Standards
    USP Roundtable for DS Protein Standards Hosted on February 07, 2017 USP–U.S., Rockville, MD Discussion Agenda Identification Tests for Proteins from Various Sources Quantitative Determination of Proteins Determination of the Purity of Proteins Limits for Contaminants in Proteins Labelling, Packaging, Storage, and Handling 2 Identification Tests for Proteins from Various Sources Current identification tests for proteins used in industry Comprehensive supplier chain qualification program helps reduce routine ID tests at the manufacturing site. Some manufacturers audit suppliers on a quarterly or annual basis. Typical identification tests: appearance, organoleptic, Kjeldahl, Near Infrared (NIR) for process monitoring and QC release. Amino acid profiling is used on a demand basis by customers. Suggested identification tests for proteins from various sources Manufacturers were aware of advanced tests: electrophoresis, CE, peptide mapping, mass spectrometry, ELISA for plant based proteins. Suggested that amino acid profiling in combination with protein profiling with electrophoresis (SDS PAGE) is feasible and suitable. 3 Quantitative Determination of Proteins from Various Sources Current quantification tests for different sources The standard method for protein quantification in industry is Kjeldahl or combustion (Dumas). NIR is commonly used for protein quantification. Total amino acid (AA) contents is believed to provide accurate protein contents. Suggested quantification tests for protein ingredients and finished products containing proteins from various sources Suggested that Kjeldahl or Dumas is a widely accepted quantification method. Total Amino Acids (AA) can be used as a complementary method to Kjeldahl or Dumas. Total AA methods require further standardization and validation. 4 Determination of the Purity of Proteins from Various Sources Impurities/specific tests for proteins Dairy protein industry routinely test for loss on drying (LOD), ash, fat and lactose.
    [Show full text]
  • Thermodynamics and Reaction Mechanism of Urea Decomposition† Cite This: Phys
    PCCP View Article Online PAPER View Journal | View Issue Thermodynamics and reaction mechanism of urea decomposition† Cite this: Phys. Chem. Chem. Phys., 2019, 21,16785 a b b b Steffen Tischer, * Marion Bo¨rnhorst, Jonas Amsler, Gu¨nter Schoch and Olaf Deutschmann ab The selective catalytic reduction technique for automotive applications depends on ammonia production from a urea–water solution via thermolysis and hydrolysis. In this process, undesired liquid and solid by-products are formed in the exhaust pipe. The formation and decomposition of these Received 18th March 2019, by-products have been studied by thermogravimetric analysis and differential scanning calorimetry. Accepted 5th July 2019 A new reaction scheme is proposed that emphasizes the role of thermodynamic equilibrium of the DOI: 10.1039/c9cp01529a reactants in liquid and solid phases. Thermodynamic data for triuret have been refined. The observed phenomenon of liquefaction and re-solidification of biuret in the temperature range of 193–230 1Cis rsc.li/pccp explained by formation of a eutectic mixture with urea. Creative Commons Attribution-NonCommercial 3.0 Unported Licence. 1 Introduction and ammonium ISE (ion-selective electrode) measurements. Concluding from experimental results and literature data, 23 Air pollution by nitrogen oxides from Diesel engines is a major possible reactions including urea and its by-products biuret, problem concerning the environment and society. Therefore, cyanuric acid, ammelide, ammeline and melamine are presented. governments follow the need to regulate emissions by law (e.g., Further, cyanate and cyanurate salts and cyanamide are 715/2007/EG, ‘‘Euro 5 and Euro 6’’).1 The favored method to proposed as possible intermediates of high temperature urea reduce nitrogen oxides is selective catalytic reduction (SCR) decomposition.
    [Show full text]
  • 4 Hazard Evaluation of Flame Retardants for Printed Circuit Boards
    FLAME RETARDANTS IN PRINTED CIRCUIT BOARDS Chapter 4 FINAL REPORT August 2015 EPA Publication 744-R-15-001 4 Hazard Evaluation of Flame Retardants for Printed Circuit Boards This chapter summarizes the toxicological and environmental hazards of each flame-retardant chemical that was identified for potential functional use in printed circuit boards (PCBs) laminates. Evaluations of chemical formulations may also include associated substances (e.g., starting materials, by-products, and impurities) if their presence is specifically required to allow that alternative to fully function in the assigned role. Otherwise, pure substances were analyzed in this assessment. Users of the alternative assessments should be aware of the purity of the trade product they purchase, as the presence of impurities may alter the hazard of the alternative. Toxicological and environmental endpoints included in the hazard profiles are discussed in Section 4.1 along with the criteria used to evaluate each hazard endpoint. Data sources and the review methodology are described in Section 4.2. The report then offers a detailed description of the utility of physical-chemical properties in understanding hazard in Section 4.3 and the process of evaluating human health and environmental endpoints in Section 4.4 and Section 4.5, respectively. A discussion of the evaluation of endocrine activity is included in Section 4.6. The characteristics of each chemical included in the alternatives assessment are summarized in the comparative hazard summary table in Section 4.8. Lastly, the collected data and hazard profile of each chemical are presented in Section 4.9. 4.1 Toxicological and Environmental Endpoints The assessment of endpoints with the intent to create hazard profiles for a Design for the Environment (DfE) alternatives assessment follows the guidance of the DfE Program Alternatives Assessment Criteria for Hazard Evaluation (U.S.
    [Show full text]
  • Title Synthesis of Melamine from Urea, II Author(S)
    Title Synthesis of melamine from urea, II Author(s) Kinoshita, Hideo The Review of Physical Chemistry of Japan (1954), 24(1): 19- Citation 27 Issue Date 1954-09-10 URL http://hdl.handle.net/2433/46705 Right Type Departmental Bulletin Paper Textversion publisher Kyoto University The Review of Physical Chemistry of Japan Vol. 24 No. 1 (1954) SYNTHESIS OF MELAMINE FROM UREA, II BS' HILan 1{IYU$H IT Ai it Introduction It was reportedil that the reaction of yielding melamine from urea begins from 275'G, reaches equi]ibrium within 6 hours at 325`C and there is no considerable change in the quantity and the yield of melamine above 325°C. And it was recognized that the reaction velocity is faster, as the packing ratioisgreater and so the pressure of gas phase is-higher. The yield of melamine was calculated from the following equation and the maximum yield was 99.4b. 6NH,CONH_ _ (NH_CN), + 6NH, + 3C0. (1) Moreover, as the intermediate products of this reaction, biuret, cyanuric acid and the water insoluble were obtained. The nitrogen content of this water insoluble ~cas dis- tributedbetween 45.4 and 55.7%. For the purpose of studying the process of this reaction, the author experimented the following cases, the reaction of urea under the condition of existing excess ammonia, the reaction between cyanuric acid and ammonia, the reaction between the water Insoluble and ammonia, and the reaction between melamine and water. These results are compared with those of the previous paper, and moreover the author makes clear that the water insoluble consists of ammelide and ammeline.
    [Show full text]
  • Contaminants – Food Compendium
    Solutions that meet your demands for food safety testing Excellent choices for food applications Contaminants Acrylamides > Return to Table of Contents > Search entire document Gas Chromatography/Mass Spectrometry Approaches to the Analysis of Acrylamide in Foods Application Food Safety Author Introduction Bernhard Rothweiler The discovery announced in April 2002 by scien- Agilent Technologies tists at Sweden’s National Food Administration of Deutschland GmbH acrylamide (2-propenamide) in fried and baked Hewlett-Packard Strasse 8 foods at levels many times that allowed in water 76337 Waldbronn suggested a much higher exposure than previously Germany estimated [1-3]. Acrylamide (Figure 1), a known neurotoxin, is considered a probable human car- Eberhardt Kuhn cinogen. The World Health Organization considers Agilent Technologies, Inc. 0.5 µg/L the maximum level for acrylamide in 91 Blue Ravine Road water. However, foods such as french fries, baked Folsom, CA potato chips, crisp breads, and other common USA cooked foods, were found to contain acrylamide Harry Prest between 100 and 1000 µg/kg. Acrylamide was not found in the raw foodstuffs and cooking by boiling Agilent Technologies, Inc. produced no detectable levels. Recent work has 5301 Stevens Creek Blvd. suggested that acrylamide forms via the Maillard Santa Clara, CA reaction, which occurs when amino acids and USA sugars (for example, asparagine and sucrose) are heated together [4]. The concern over these rela- Abstract tively high concentrations has led to studies of the occurrence of acrylamide in a wide variety of Discovery of acrylamide in cooked foods has required an foods. examination of foods for potential exposure. A classic H O approach employs extracting acrylamide from the food with water and converting the acrylamide to brominated H H2N derivatives.
    [Show full text]
  • Hydrophilic Interaction Chromatography (HILIC) for Simultaneous and Fast Analysis of Melamine, Cyanuric Acid, and Other Metabolites in Milk and Protein- Rich Powders
    Hydrophilic Interaction Chromatography (HILIC) for Simultaneous and Fast Analysis of Melamine, Cyanuric Acid, and other Metabolites in Milk and Protein- Rich Powders Eugene Chang, Varian, Inc., 25200 Commercentre Dr., Lake Forest, CA 92630, U.S.A. James Neal-Kababick, Flora Research Laboratories,1000 SE M St # B, Grants Pass, OR 97526, U.S.A. Ritu Arora, Varian, Inc., 25200 Commercentre Dr.,Lake Forest, CA 92630, U.S.A. Abstract Hydrophilic Interaction Chromatography (HILIC) is one of the fastest growing chromatographic techniques employed today for retaining polar analytes. It overcomes the shortcomings of some of the other retention mechanisms for polar compound analysis like ion-exchange, ion-pair reversed-phase, or making use of polar modified chemistries. These techniques mainly employ buffers which have either high ionic strength and/or are not compatible with MS detection. Moreover, ion pair separation of both an acid and a base in the same analysis is difficult. High visibility and the potential public-health threat regarding the concern over melamine adulteration in both animal and human-food sources has prompted many government agencies including the U.S. FDA to release standard test methods for the analysis of melamine and related compounds like cyanuric acid in protein materials (1). Besides these analytes, several food manufacturers require a method for other metabolites like ammelide and ammeline. Melamine and its metabolites are extremely polar compounds Melamine and serve as very good candidates for HILIC chromatography. The U.S. FDA method for melamine and cyanuric acid was followed with some modifications made to establish a method for all four compounds.
    [Show full text]
  • 2342 Introduction
    2342 J. S. BLAIR AND J. M. BRAHAM amine base is fairly uniform in regard to toxicity and sulfur content irre- spective of the period of formation during the reduction. Amino hydroxyarseno compounds in general contain the fewest sulfur atoms when prepared from the amino acids. Fixation of the hydroxyl hydrogen in the nitrohydroxyarsonic acids tends to make the hydrosulfite reduction abnormal, and the products, when isolable, contain more sulfur than analogous substances prepared without fixation of this hydrogen atom. The hydroxyl hydrogen ortho to the nitro group seems to play an important role in the formation of arseno compounds of the type under consideration. Probably the sulfonic acid group found in certain samples of arsphen- amine enters the ring by way of the nitrogen atom with the intermediate formation of a sulfamic acid. I wish to thank Dr. Reid Hunt for determining the toxicity of the samples involved in this work and Mr. Arthur J. Norton for his assistance in puri- fying the hydrosulfite and analyzing some of the substances obtained. BOSTON,MASSACHCSETTS [COKTRIBUTION FROM THE FIXEDNITROGEN RESEARCH LABORATORY] MECHANISM OF GUANIDINE FORMATION IN FUSED MIXTURES OF DICYANODIAMIDE AND AMMONIUM SALTS BY J. S. BLAIRAND J. M. BRAHAY' Received July 13, 1922 Introduction In the course of an investigation on the use of calcium cyanamide as a source of nitroguanidine and other guanidine derivatives, some experi- ments were performed in which dicyanodiamide was fused with various ammonium salts, with the original purpose of determining the feasibility of this method for the production of guanidine salts. Their formation in this manner has been described by several investigators, but the opti- mum conditions for guanidine production had not at that time been as- certained.
    [Show full text]
  • Assembly Study of Melamine and Its Derivatives
    International Journal of Organic and Inorganic Chemistry Editorial Article Assembly Study of Melamine and its Derivatives Emad Yousif*, Basheer A. Hamad, Ahmed A. Ahmed, Dina S. Ahmed Department of Chemistry, College of Science, Al-Nahrain University, Iraq Received: 23 August, 2018; Accepted: 23 August, 2018; Published: 25 August, 2018 *Corresponding Author: Emad Yousif, Department of Chemistry, College of Science, Al-Nahrain University, Baghdad 10072, Iraq [email protected] Copyright: © 2018 Yousif E, Hamad BA, et al Assembly Study of Melamine and its Derivatives. Int J Org Inorg Chem; 1(1): 1-3. Editorial attributed to the adsorption of these Melamine is well established nitrogen compounds by their protonizable amino rich triazine ring containing molecule with groups and non-bonding electrons of nitrogen three additional nitrogen atoms those can atoms and π-electrons of three double (-C=N- easily protonate and enhance the solubility of ) bonds [2,3]. Melamine is a nontoxic, white, polar solvents [1]. odourless hetero-aromatic substance, which Figure (1): Structure of melamine. is used as a raw material for various industrial products, mostly as a high- molecular weight compound obtained from reaction with formaldehyde. Melamine- formaldehyde (MF) resins are obtained by Recently, derivatization of melamine poly-condensation of melamine with gained the significant advanced for variety of formaldehyde in acidic or basic media [4]. purposes including corrosion inhibition. Figure (2): Melamine formaldehyde (MF). Literature survey revealed that melamine and its several derivatives have been investigated as effective corrosion inhibitors for metals and alloys in aggressive solutions owing to their high protection ability which is in turn Yousif E, Hamad BA, et al (2018) Assembly Study of Melamine and its Derivatives.
    [Show full text]
  • Safety Data Sheets
    SAFETY DATA SHEETS According to Globally Harmonized System of Classification and Labelling of Chemicals (GHS) - Sixth revised edition Version: 1.0 Creation Date: Feb. 5, 2018 Revision Date: Feb. 5, 2018 1. Identification 1.1 GHS Product identifier Product name 2,4,6-Triamino-s-triazine 1.2 Other means of identification Product number A501506 Other names Theoharn 1.3 Recommended use of the chemical and restrictions on use Identified uses Used for research and development only.Adhesives and sealant chemicals,Dyes,Flame retardants,Intermediates,Laboratory chemicals,Paint additives and coating additives not described by other categories,Pigments,Plasticizers Uses advised against no data available 1.4 Supplier's details Company Sangon Biotech (Shanghai) Co., Ltd. Address 698 Xiangmin Road, Songjiang, Shanghai 201611, China Telephone +86-400-821-0268 / +86-800-820-1016 Fax +86-400-821-0268 to 9 1.5 Emergency phone number Emergency phone +86-21-57072055 number Service hours Monday to Friday, 9am-5pm (Standard time zone: UTC/GMT +8 hours). 2. Hazard identification 2.1 Classification of the substance or mixture Not classified. 2.2 GHS label elements, including precautionary statements Pictogram(s) No symbol. Signal word No signal word Hazard statement(s) none Precautionary statement(s) 2,4,6-Triamino-s-triazine Page 1 of 9 Prevention none Response none Storage none Disposal none 2.3 Other hazards which do not result in classification no data available 3. Composition/information on ingredients 3.1 Substances Chemical Common names and CAS EC Concentration name synonyms number number Melamine 2,4,6-Triamino-s-triazine 108-78-1 203-615-4 ≥98% 4.
    [Show full text]
  • Analysis of Melamine and Cyanuric Acid by Liquid Chromatography with Diode Array Detection and Tandem Mass Spectrometry Byungchul Kim
    The University of Maine DigitalCommons@UMaine Electronic Theses and Dissertations Fogler Library 5-2009 Analysis of Melamine and Cyanuric Acid by Liquid Chromatography with Diode Array Detection and Tandem Mass Spectrometry Byungchul Kim Follow this and additional works at: http://digitalcommons.library.umaine.edu/etd Part of the Food Chemistry Commons Recommended Citation Kim, Byungchul, "Analysis of Melamine and Cyanuric Acid by Liquid Chromatography with Diode Array Detection and Tandem Mass Spectrometry" (2009). Electronic Theses and Dissertations. 12. http://digitalcommons.library.umaine.edu/etd/12 This Open-Access Dissertation is brought to you for free and open access by DigitalCommons@UMaine. It has been accepted for inclusion in Electronic Theses and Dissertations by an authorized administrator of DigitalCommons@UMaine. ANALYSIS OF MELAMINE AND CYANURIC ACID BY LIQUID CHROMATOGRAPHY WITH DIODE ARRAY DETECTION AND TANDEM MASS SPECTROMETRY By Byungchul Kim B.E. Pukyong National University, 1998 M.S. Pukyong National University, 2000 M.S. University of Arkansas, 2004 A THESIS Submitted in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy (in Food and Nutrition Sciences) The Graduate School The University of Maine May, 2009 Advisory Committee: Rodney J. Bushway, Professor of Food Science & Human Nutrition-Co chair L. Brian Perkins, Assistant Research Professor of Food Science-Co chair Alfred A. Bushway, Professor of Food Science & Human Nutrition Beth Calder, Extension Food Science Specialist and Assistant Professor of Food Science & Human Nutrition Lawrence A. LeBlanc, Assistant Research Professor of Food Science Titan Fan, President of Beacon Analytical Systems, Inc. © 2009 Byungchul Kim All Rights Reserved ii LIBRARY RIGHTS STATEMENT In presenting this thesis in partial fulfillment of the requirements for an advanced degree at The University of Maine, I agree that the Library shall make it freely available for inspection.
    [Show full text]
  • United States Patent (19) 11 Patent Number: 4,963,674 Mason Et Al
    United States Patent (19) 11 Patent Number: 4,963,674 Mason et al. 45 Date of Patent: Oct. 16, 1990 (54) PURIFICATION OF CYANURIC ACID Primary Examiner-John M. Ford 75 Inventors: Robert W. Mason, Lake Charles; Attorney, Agent, or Firm-James B. Haglind; Paul Thomas C. Parker, Sulphur, both of Weinstein La. 57 ABSTRACT 73 Assignee: Olin Corporation, Cheshire, Conn. A process for the purification of crude cyanuric acid containing aminotriazine compounds as impurities (21) Appl. No.: 454,653 which comprises digesting the crude cyanuric acid in an (22 Filed: Dec. 21, 1989 aqueous solution containing low concentrations of a mineral acid. The mineral acid is, for example sulfuric Related U.S. Application Data acid, nitric acid, hydrochloric acid, or phosphoric acid. 63 Continuation-in-part of Ser. No. 164,671, Mar. 7, 1988, The digestion is operated at a temperature in the range abandoned. of from about 120° C. and about 220 C. and autogenous pressure using a stoichiometric ratio of sulfuric acid to 51) Int. Cl. ............................................ COTD 251/32 aminotriazine compounds of less than 1, to produce a 52 U.S.C. .................................................... 544/192 slurry of purified cyanuric acid in an acid depleted 58 Field of Search ....... ... 544/192 ammonium sulfate solution. 56 References Cited Purification of cyanuric acid by the process of the pres U.S. PATENT DOCUMENTS ent invention permits a substantial reduction in the 2,943,088 6/1960 Westfall .............................. 544/192 amounts of acid used in the digestion and the base re 3,107,244 10/1963 Robertson ........................... 544/92 quired for ammonia stripping and neutralization of the 3,969,352 7/1976 Berkowitz ..........................
    [Show full text]