140-95-4Relevant academic research and scientific papers
Surface modification of vesicles with methylol urea
Kim, Jin-Chul,Kim, Jong-Duk
, p. 1235 - 1239 (2002)
Surface-modified vesicles were prepared using N-[3-(dimethylamino)propyl]-octadecanamide and stearic acid as bilayer-forming lipids, and N-methylol urea-dodecylamine conjugates (MU-DOA) as a surface modifier. The conjugation of MU to DOA was confirmed by FTIR spectra. MU-DOA was incorporated into the vesicles by co-homogenization of the lipids and MU-DOA, and the incorporated MU-DOA was then reacted with MU in aqueous bulk phase through a self-condensation reaction between the methylols under an acidic condition at 70°C. On a scanning electron microscope, the vesicles were spherical and multilamellar, and they exhibited thin polymer films on their surfaces. The incorporation of MU-DOA into the bilayer and the surface coating of the vesicles did not significantly influence the transition temperature of the vesicles. The absolute values of zeta potentials of the surface-modified vesicles were smaller than those of the unmodified vesicles, and the point of zero charge was shifted from ca. pH 9.5 to ca. pH 6.5 by the surface modification.
Henry and Mannich reactions of polynitroalkanes in ionic liquids
Epishina, Margarita A.,Ovchinnikov, Igor V.,Kulikov, Alexander S.,Makhova, Nina N.,Tartakovsky, Vladimir A.
, p. 21 - 23 (2011)
Based on Henry and Mannich reactions of polynitroalkanes for the first time implemented in ionic liquids, ecologically pure and safe methods for the synthesis of polynitro alcohols and N-2,2,2-trinitroethyl derivatives of low basic amino compounds (urea, acetamide, 4-amino-3-methylfuroxan) have been elaborated.
Competitive adsorption of three phenolic compounds to hydrophilic urea-formaldehyde macroporous foams derived from lignin-based Pickering HIPEs template
Pan, Jianming,Luo, Jialu,Cao, Jun,Liu, Jinxing,Huang, Wei,Zhang, Wenli,Yang, Lili
, p. 93894 - 93904 (2016)
Hydrophilic urea-formaldehyde macroporous foams (UFMF) were simply synthesized by templating oil-in-water Pickering high internal phase emulsions (HIPEs) solely stabilized by lignin particles. Morphology and structure of the UFMF can be easily tailored by varying the experimental compositions of Pickering HIPEs and polymerization time. Due to their porous matrix, hydrophilic surface, and high content of binding groups (such as hydroxyl groups and carbonyl groups), as-prepared UFMF was adopted for the removal of three phenolic compounds (PCs) from aqueous solution. The influences of pH, solution temperature, contact time, and initial concentration of 2,4,5-trichlorophenol (2,4,5-TCP), 2,4,6-trichlorophenol (2,4,6-TCP) and 4-nitrophenol (4-NP) on adsorption capacity and competitive adsorption of multi PCs were investigated via the batch mode experiments. The adsorption kinetics and adsorption isotherms fit well by a pseudo-second-order model and Langmuir model, respectively. The max adsorption capacity of 2,4,5-TCP, 2,4,6-TCP and 4-NP at 25 °C are 116.3 mg g-1, 78.74 mg g-1, 29.41 mg g-1, respectively, and their adsorption rate follows the order 2,4,5-TCP > 2,4,6-TCP > 4-NP. Moreover, the group type and position effects both influence the adsorption, and follow the order: 2,4,5-position substitution of chloride > 2,4,6-position substitution of chloride > 4-position substitution of nitro-group, showing that the substitution with the more groups has the higher adsorption affinity.
Utilization of wheat straw for the preparation of coated controlled-release fertilizer with the function of water retention
Xie, Lihua,Liu, Mingzhu,Ni, Boli,Wang, Yanfang
, p. 6921 - 6928 (2012)
With the aim of improving fertilizer use efficiency and minimizing the negative impact on the environment, a new coated controlled-release fertilizer with the function of water retention was prepared. A novel low water solubility macromolecular fertilizer, poly(dimethylourea phosphate) (PDUP), was "designed" and formulated from N,N′-dimethylolurea (DMU) and potassium dihydrogen phosphate. Simultaneously, an eco-friendly superabsorbent composite based on wheat straw (WS), acrylic acid (AA), 2-acryloylamino-2- methyl-1-propanesulfonic acid (AMPS), and N-hydroxymethyl acrylamide (NHMAAm) was synthesized and used as the coating to control the release of nutrient. The nitrogen release profile and water retention capacity of the product were also investigated. The degradation of the coating material in soil solution was studied. Meanwhile, the impact of the content of N-hydroxymethyl acrylamide on the degradation extent was examined. The experimental data showed that the product with good water retention and controlled-release capacities, being economical and eco-friendly, could be promising for applications in agriculture and horticulture.
Improved performance of soy protein adhesive with melamine-urea-formaldehyde prepolymer
Chen, Yuzhu,Feng, Qiaoling,Jiang, Ke,Jing, Mingwei,Lei, Zhenghui,Lv, Wenxin,Tan, Hailu,Xiao, Hui,Yi, Maoyu
, p. 27126 - 27134 (2021/08/24)
In recent years, soy protein adhesive, as an environmentally friendly bio-based adhesive, has attracted extensive attention. In this study, in order to ameliorate the bonding quality of soy protein isolate (SPI) adhesive, the melamine-urea-formaldehyde prepolymer (MUFP) was synthesized, and different amounts of it were introduced into the SPI adhesive as a cross-linking agent. Fourier transform infrared (FT-IR) spectroscopy, gel permeation chromatography (GPC), thermogravimetric analyze (TGA), and scanning electron microscopy (SEM) were used to analysis the mechanism of modification. The results of plywood test indicated that the wet bonding strength of the adhesives was first increased and then decreased with an increase in the amount of MUFP additive. FT-IR, TGA, and SEM tests suggested that the introduction of MUFP could promote the establishment of a cross-linking structure in the cured adhesive layer to improve the bonding quality of adhesives, but presence of excessive MUFP could introduce hydrophilic groups and adversely affect water resistance. This journal is
Quantitative and qualitative 1H, 13C, and 15N NMR spectroscopic investigation of the urea-formaldehyde resin synthesis
Steinhof, Oliver,Kibrik, Eleonore J.,Scherr, Guenter,Hasse, Hans
, p. 138 - 162 (2014/04/03)
Urea-formaldehyde resins are bulk products of the chemical industry. Their synthesis involves a complex reaction network. The present work contributes to its elucidation by presenting results from detailed NMR spectroscopic studies with different methods. Besides1H NMR and13C NMR, 15N NMR spectroscopy is also applied.15N-enriched urea was used for the investigations. A detailed NMR signal assignment and a model of the reaction network of the hydroxymethylation step of the synthesis are presented. Because of its higher spectral dispersion and the fact that all key reactions directly involve the nitrogen centers,15N NMR provides a much larger amount of detail than do1H and13C NMR spectroscopy. Symmetric and asymmetric dimethylol urea can be clearly distinguished and separated from monomethylol urea, trimethylol urea, and methylene-bridged urea. The existence of hemiformals of methylol urea is confirmed. 1,3,5-Oxadiazinan-4-on (uron) and its derivatives were not found in the reaction mixtures investigated here but were prepared via alternative routes. The molar ratios of formaldehyde to urea were 1, 2, and 4, the pH values 7.5 and 8.5, and the reaction temperature 60 °C. Copyright 2014 John Wiley & Sons, Ltd. 15N-enriched urea is used in combination with quantitative15N and13C NMR spectroscopy and a Virtual Reference. This allows for a detailed peak assignment and absolute quantification of the early steps of this industrial process, which involves a complex reaction network. A detailed peak assignment for all three nuclei, a full quantitative description of the reaction mixture's composition and a model describing changes in shift depending on formaldehyde substitution are given. Copyright
Binding of phenols in the urea-formaldehyde-water system and the role of precondensation stage in the synthesis of polymethyleneurea
Maslosh,Zamashchikov,Bezbozhnaya
, p. 1197 - 1200 (2007/10/03)
The precondensation stage (keeping of a solution of urea and formaldehyde in a neutral medium) in the synthesis of polymethyleneurea is examined experimentally and by mathematical simulation.
HYDROXYMETHYL DERIVATIVES OF UREA AND FORMALDEHYDE: CONDITIONS OF THEIR FORMATION.
Bulygina,Gritsenko,Sokolovskaya,Sarbaev
, p. 419 - 421 (2007/10/02)
The polycondensation process may be represented in the form of a reaction between functional groups, with formation of monohydroxymethylurea (I) and dihydroxymethylurea (II). Formation of these derivatives depends on the PH, temperature, and excess of formaldehyde of urea. When the reaction is conducted in a weakly alkaline medium, either mono- or dihydroxymethylurea is formed. Formation of monohydroxymethylurea does not go to completion in an alkaline medium, as the reaction is reversible. The reaction can be shifted toward increase of the monohydroxymethylurea yield by the use of excess formaldehyde. On the basis of their investigations the authors propose specific conditions for preparation of pure mono- and dihydroxymethylurea. The synthesis is based on the reaction of urea with formaldehyde in aqueous solution containing 44 mass % of water at 1:1 molar ratio of urea to formaldehyde for formation of monohydroxymethylurea, and 1:2 molar ratio with 5% excess of formaldehyde over the stoichiometric ratio for formation of dihydroxymethylurea.
Canonical Chemical Theories Exemplified by the Mehtylolation of Urea and Melamine
Gebregiorgis, Taddesse,Gordon, Manfred
, p. 359 - 382 (2007/10/02)
Old and recent data on equilibria and kinetics of methylolation of urea and melamine are analysed.The theoretical framework affords a sequence, claimed to be canonical of successive phenomenological approximations.The theory, expounded earlier, begin with two successive schemes whose essentials go back to early work by Pauling and by Flory.The two stages here suffice to show that all the data from eight laboratories, covering the six-membered family of methylol ureas and rhe ten-membered family of methylol melamines, are in quantitative agreement, a circumstance unsespected by other workers in the field.The statisticalthermodynamic and kinetic principles involved are therefore expounded in more detail than before.Using them, very small substituent effects (e.g O.35 kJ kol-1 are deduced with high significance and accuracy.Owing largly to the recent measurement by Tomita, the methylol melamines are claimed currently to be the thermdinamically best characterised family in the chemical literature.A challenge arises for theoretical chemists to test quantum-theoreticaltechniques against the measured energetics of substituent effects in this family, and to exploit for other families the graph-theoretical analysis of molecular additivity which underlies the approximation schemes, which already well tested.
