SYNTHESIS AND PROPERTIES OF OLIGODIURETANEDIOLS BASED ON A MIXTURE OF (2,4–2,6) TOLUILENDIISOCYANATE

2021 ◽  
Vol 43 (3) ◽  
pp. 198-203
Author(s):  
S.M. KUZMENKO ◽  
◽  
E.O. SPORYAGIN ◽  
O.M. KUZMENKO ◽  
A.YA. PUZENKO ◽  
...  

The paper describes the synthesis, the reaction of a mixture of isomers (2,4–2,6) of toluilendiisocyanate with a double molar excess of aliphatic individual or oligomeric diols, a number of previously unknown oligodiuretanediols and their physicochemical constants. It is shown that with an increase in the synthesis temperature from 50 to 70 °C, the reaction time to complete depletion in the mixture of free NCO-groups decreases from 8–9 hours to 3–4 hours. The reaction temperature of 70–2 °С should be considered optimal, because at higher temperatures side reactions of free NCO-groups with already formed urethane ones are possible. Because the presence of even a small amount of moisture in the diols can provoke side effects during the urethane formation reaction, all of the above diols were dried from the adsorbed moisture by azeotropic distillation with toluene before use in the reaction. Since the final products are even at the synthesis temperature (68–70 °C) viscous liquids, and there are difficulties with the homogenization of the reaction mass during synthesis, and when unloading the finished product from the reaction plant, in all cases, the synthesis was performed in solution cyclohexanone by 50 % by weight of the final product. Control of the reaction was performed by changing the % wt. free NCO-groups in time. The reaction was considered complete if the measured % wt. free NCO-groups in the reaction mixture for at least one hour twice showed zero. The isolated oligodiuretanediols range from solid at room temperature to very viscous products, which significantly depends on the molecular weight of the diol used in the reaction (ie the concentration of urethane groups formed). They are homogeneous, transparent compounds that are readily soluble in esters, ethers, aromatic and halide-containing, aprotic solvents, ketones, poorly or completely insoluble in aliphatic saturated hydrocarbons. The structure of the synthesized oligomeric products is confirmed by functional analysis, IR–spectra. In the IR-spectra of each of the synthesized oligodiuretanediols there are no absorption bands in the region of 2270 cm-1, which confirms the complete completion of the reaction of urethane formation according to the scheme. At the same time, the absorption bands in the region of 3450 cm-1, 1720 cm-1, 1540 cm-1 are fixed, which are characteristic of the presence of urethane groups in the structure of the target products. As the chain length of the diol component –R– increases in the target product (which synchronously leads to an increase in molecular weight), the intensity of these absorption bands decreases, which is associated with a decrease in the concentration of formed urethane groups in the structure of oligodiuretanediols. The refractive index also decreases synchronously. Synthesized series of oligodiuretanediols can be used for synthesis on its basis of other classes of oligomers with the simultaneous presence in the structure of urethane groups. The ability of such compounds to be soluble in solvents of different nature has been studied, which provides information for the directions of their further use (varnishes, enamels, primers).

2021 ◽  
pp. 60-65
Author(s):  
R.S. Ismayilova ◽  
M.M. Kuliev ◽  
G.A. Akhundova

The effect on concentration of the nanofiller α-SiO2 filler and irradiation on the FTIR spectra of pure films polymer (ultra-high molecular weight polyethylene (UHMWPE)) and doped them this α-SiO2 with different concentration (0, 1, 3, 5 vol.%) were investigated using FTIR technique. The samples were irradiated for different doses like 0, 50, and 100 kGy by 60Co source with a dose rate of approximately 3.3∙10-3 kGy/h at room temperature. The correlation of absorption bands with occurrence of corresponding groups was carried out. The occurrence of a series of a characteristic absorptions bands of composites was shown.


1997 ◽  
Vol 70 (3) ◽  
pp. 519-529 ◽  
Author(s):  
J. C. Marmo ◽  
K. B. Wagener

Abstract The employment of transition metal catalysts has been a viable route in the degradation and depolymerization of unsaturated polymers. Initially, unsaturated polymers were degraded with a catalytic system containing a transition metal and a Lewis acid cocatalyst (WCl6/SnBu4). Degradation chemistry was effective in reducing the molecular weight of the polymer, however, the classical catalyst system induces side reactions which generates ill-defined products. These side reactions were obviated by using a preformed alkylidene without a Lewis acid cocatalyst, and perfectly difunctional telechelics were synthesized.


2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Xianhai Hu ◽  
Xingyuan Zhang ◽  
Jin Liu

A waterborne polyurethane-based polymeric dye (WPU-CFBB) was synthesized by anchoring 1, 4-bis(methylamino)anthraquinone (CFBB) to waterborne polyurethane chains. The number molecular weight, glass transition temperature, and average emulsion particle size for the polymeric dye were determined, respectively. This polymeric dye exhibited intriguing optical behaviors. The polymeric dye engendered two new absorption bands centered at about 520 nm and 760 nm if compared with CFBB in UV-vis spectra. The 760 nm peak showed hypsochromic shift with the decrease of average particle sizes. The polymeric dye dramatically demonstrated both hypsochromic and bathochromic effects with increasing temperature. The fluorescence intensity of the polymeric dye was much higher than that of CFBB. It was found that the fluorescence intensities would be enhanced from 20°C to 40°C and then decline from 40°C to 90°C. The fluorescence of the polymeric dye emulsion was very stable and was not sensitive to quenchers.


2015 ◽  
Vol 11 (8) ◽  
pp. 3866-3872
Author(s):  
E.A. Masimov ◽  
Etibar Hummat Ismailov ◽  
S.Y. Odzhaqverdiyeva

Dynamic light scattering (DLS) method in combination with the UV/VIS spectrophotometry is used to study the interaction of polyethylene- glycols with a molecular weight  6000 ( PEG6000 ) with sodium salts of citric and succinic acids in aqueous solutions. The values of density, viscosity, refractive and diffusion indexes, the values of the hydrodynamic diameter, wavelength electronic absorption bands for PEG6000 aqueous solutions, their mixtures with succinic and citric acids are determined. It was shown that depending on the composition of the solutions the values of hydrodynamic diameter for aqueous solutions containing 1-5 wt.% PEG6000 and their mixtures with succinic and citric acids (~ 1 wt%) ranges from 3.6 to 5.2 nm. It is assumed that the formation of complexes with the sizes  that are within the above range is due to the features of interaction  and the structure of the complexes formed in solution.


Author(s):  
Д.А. МЕТЛЕНКИН ◽  
Ю.Т. ПЛАТОВ ◽  
Р.А. ПЛАТОВА ◽  
А.Е. РУБЦОВ ◽  
А.М. МИХАЙЛОВА

Для идентификации кофе используют методы газовой и жидкостной хроматографии, которые дают точную и подробную информацию о его химическом составе, однако трудоемки, сложны по пробоподготовке и непригодны для оперативного мониторинга качества. Цель настоящего исследования – разработка и апробация метода идентификации кофе по ботаническому виду, географическому месту произрастания и обжарке с применением Фурье-ИК-спектроскопии и многомерного анализа. В качестве объектов исследования были образцы кофе в зернах, различающиеся по ботаническому виду (арабика/робуста), географическому месту произрастания (Азия/Америка/Африка) и обжарке (жареный/нежареный). Для разработки моделей идентификации кофе в зернах была сформирована база спектральных данных и применены методы многомерного анализа – метод главных компонент (МГК) и дискриминантный анализ (ДА). ИК-спектры образцов кофе регистрировали с помощью Фурье-ИК-спектрометра Bruker ALPHA с алмазным модулем НПВО в диапазоне 4000–400 см–1 при разрешающей способности спектрометра 2 см–1. Спектральные данные были экспортированы из встроенного программного обеспечения OPUS 7.3.5.0 в Excel. При анализе матрицы спектральных данных выявлены наиболее интенсивные полосы поглощения ИК-спектра, приписываемые наличию функциональных групп воды, липидов, полисахаридов, кофеина и хлорогеновой кислоты в кофе. При сравнении ИК-спектров образцов кофеина, декофеинизированного кофе и кофе в зернах выявлены полосы поглощения спектра, которые можно использовать для построения калибровочной модели содержания кофеина в составе кофе в зернах. По спектральным данным МГК построена многомерная модель градации образцов кофе в зависимости от ботанического вида и наличия обжарки. По матрице факторных нагрузок выявлены полосы поглощения спектра, объясняющие различия образцов по ботаническому виду и обжарке и вносящие наибольший вклад в разделение образцов кофе на группы. Методом ДА по 19 переменным – коэффициентам поглощения на волновых числах спектра разработана система классификационных функций градации образцов кофе по географическому месту произрастания. Доказано, что сочетание Фурье-ИК-спектроскопии с методами многомерного анализа можно использовать как быстрый и неразрушающий инструмент для идентификации кофе в зернах. Gas and liquid chromatography methods are used to identify coffee. They provide accurate and detailed information about its chemical composition; however they are time-consuming, complex in sample preparation and unsuitable for operational quality monitoring. The purpose of this study is to develop and test a method for identifying coffee by botanical species, geographical place of growth and roasting using FTIR-spectroscopy and multivariate analysis. Samples of coffee beans were selected as objects of research, differing in botanical type (Arabica/Robusta), geographical place of growth (Asia/America/Africa) and roasting (roasted/not roasted). To develop models for the identification of grain coffee, a spectral database was formed and the methods of multivariate analysis were applied: principal components analysis (PCA), discriminant analysis. The IR-spectra of coffee samples were recorded using a Bruker ALPHA FTIR-spectrometer with a diamond module in the range of 4000–400 cm–1 with a resolution of the spectrometer of 2 cm–1. Spectral data were exported from the OPUS 7.3.5.0 embedded software to Excel. During analysis the matrix of spectral data, the most intense absorption bands of the IR-spectrum were revealed, attributed to the presence of functional groups of water, lipids, polysaccharides, caffeine and chlorogenic acid in grain coffee. By comparison the IR spectra of the samples: caffeine, decaffeinated coffee and grain coffee, absorption bands of the spectrum were revealed, which can be used to build a calibration model of the caffeine content in the composition of coffee beans. Using PCA based on the spectral data, a multivariate model of the gradation of coffee by botanical type and depending on the roast was build. According to the matrix of factor loadings, absorption bands of the spectrum were revealed, explaining the differences between the samples in botanical type and roasting and making the greatest contribution to the division of coffee samples into groups. By the method of discriminant analysis using 19 variables – absorption coefficients at the wave numbers of the spectrum – a system of classification functions for the gradation of grain coffee samples according to the geographical place of growth has been developed. It is proved that the combination of FTIR-spectroscopy with multivariate analysis methods can be used as a fast and non-destructive tool for identifying coffee beans.


Clay Minerals ◽  
1981 ◽  
Vol 16 (4) ◽  
pp. 375-382 ◽  
Author(s):  
Jose L. Rendon ◽  
Carlos J. Serna

AbstractHematites obtained by heating goethite gave different IR absorption spectra depending on the temperature of formation. Hematites formed between 250–600°C consisted of lath-like crystals (average size 0.4 ×0.08 µm) and showed, in accordance with theoretical predictions, very similar IR spectra whose absorption bands could all be assigned to surface mode vibrations. However, significantly different IR spectra were given by hematites formed between 700–950°C, the differences being correlated with variations in the size and shape of the particles. Differences observed in the IR spectra of powder hematite do not therefore justify new names for the mineral, as have been proposed in the literature.


1997 ◽  
Vol 52 (5) ◽  
pp. 457-461 ◽  
Author(s):  
Sn. Bakalova ◽  
A. Georgieva ◽  
P. Nikolov ◽  
E. Stanoeva

Abstract The absorption and luminescence characteristics of a group of newly synthesized methyl esters of 2-alkyl (p-substituted-aryl) -aminomethylene-3,4-dihydro-1(2 H)-naphthalenone-4-carboxylic acids have been investigated. The studied compounds may exist in three tautomeric forms. On the basis of comparison of their electronic spectra to those of similar substances, the observed substituent effect on the position of the UV-VIS absorption bands, the IR spectra and the results of PPP-SCF-CI quantum-chemical calculations it is concluded that the keto tautomer predominates in solution.


1975 ◽  
Vol 30 (3-4) ◽  
pp. 215-218 ◽  
Author(s):  
A. H. Abou El Ela ◽  
F. M. Abdelkerim ◽  
H. F. Aly ◽  
H. H. Afifi

The visible and near IR spectra of the ammonium salt of cupferron and manganese, cobalt, nickel and copper divalent cupferrate complexes are investigated. New absorption bands observed are given and assigned using the Tanabe-Sugano diagrams. In the absorption spectra of the divalent transition metal cupferrates a characteristic shift in the maxima and minima appears. Solvent effects on this shift were investigated.


Sign in / Sign up

Export Citation Format

Share Document