Identification of absorption bands corresponding to C-C1 stretching vibrations in the IR spectra of organic compounds

1991 ◽  
Vol 55 (3) ◽  
pp. 863-866
Author(s):  
B. V. Lopatin ◽  
V. G. Vinokurov ◽  
N. B. Lopatina ◽  
V. A. Berdyugin
Keyword(s):  
Ir Spectra ◽  
Organic Compounds ◽  
Absorption Bands ◽  
Stretching Vibrations

scholarly journals SYNTHESIS OF A MODIFIED 4-AMINOBENZOIC ACID DERIVATIVE UNDER ULTRASOUND CONDITIONS

2020 ◽  
Vol 2 (440) ◽  
pp. 153-155
Author(s):  
A.Kh. Zhakina ◽  
D.S. Abdrakhmanova
Keyword(s):  
Nmr Spectroscopy ◽  
Maleic Anhydride ◽  
Ir Spectra ◽  
Chemical Reactions ◽  
Biologically Active ◽  
Aminobenzoic Acid ◽  
Absorption Bands ◽  
Synthesis Time ◽  
Propenoic Acid ◽  
Stretching Vibrations

The search for new effective drugs with biologically active properties is one of the urgent problems. Recently, to intensify the process of their synthesis and increase the efficiency of chemical reactions, wave chemistry has been used. Increased interest of researchers is caused by the synthesis of compounds with biologically active properties using the method of ultrasonic treatment (US). It is known that derivatives of p-aminobenzoic acid and their esters are synthetic analogues of natural compounds, and pyrrolidone derivatives have high hypnotic, anticonvulsant, antiarrhythmic activity, which stimulates the synthesis of new biologically active compounds. In a brief report, the possibility of synthesizing ethyl-4-(2,5-dioxo-2,5-dihydro-1H-pyrrolyl) benzoate from 3-[(4-ethoxycarbonyl) phenylcarbamoyl]-2-propenoic acid using ultrasonic activation through a step is considered disclosure of the furan cycle with further cyclization. Ethyl ester p-aminobenzoic acid and maleic anhydride were used as starting reagents. An ultrasound device IL-100-6/2, equipped with a magnetostrictive transducer, with an operating frequency of 22 kHz, with a maximum power of 1200 W and a cylindrical waveguide, was used as a source of ultrasound. The synthesis of 3-[(4-ethoxycarbonyl) phenylcarbamoyl]-2-propenoic acid was carried out by reacting the starting reagents at equimolar ratios and room temperature. The US time was 10 minutes. The reaction proceeds smoothly. Ultrasound has a significant effect on the rate of chemical reactions and can increase the yield of the final product. Under classical conditions, the synthesis time was 180 minutes; using ultrasound, the synthesis time was reduced by 3 times. The product yield was 92%. The structure and composition of the obtained compound was confirmed by IR- and H1 NMR-spectroscopy. In the IR-spectra of the obtained compound, there are absorption bands of the amide group (NHCO) in the region of 3280, 3190 cm-1, absorption bands of the carbonyl group (C=O), characteristic in the region of 1670 cm-1, absorption band (COC) in the region of 1230 cm-1. The resulting compound, 3-[(4-Ethoxycarbonyl) phenylcarbamoyl]-2-propenoic acid, made it possible to study the step of opening the furan ring, with further cyclization. Ethyl 4-(2,5-dioxo-2,5-dihydro-1H-pyrrolyl) benzoate was obtained in 89% yield by azeotropic distillation of water in the presence of toluenesulfonic acid in a DMFA-toluene mixture. The resulting product is a light yellow powder with melting point 114-115°C. The structure and composition of the obtained compound was confirmed by IR-and H1 NMR-spectroscopy. In the IR-spectra of the obtained compound, the stretching vibrations of the НС=СН group manifest themselves in the form of a low-intensity but characteristic signal at 3100-3090 cm-1, stretching vibrations of the С=О group as intense bands in the region of 1700-1680 cm-1 and a weak overtone at 3465-3450 cm-1, stretching vibrations of the COC group in the region of 1245 cm-1. When analyzing the Н1 NMR-spectrum of a compound, ethyl 4-(2,5-dioxo-2,5-dihydro-1Н-pyrrolyl) benzoate, the signals of aromatic four protons Н1- Н2 (4Нaryl, 3JНН 8 Hz) are recorded in the field of weak fields: H1 doublet at 7.51 ppm. and a doublet at 8.05 ppm. Signals of the ethyl fragment: (3H, CH3, 3JHH 8 Hz), appear as a singlet at 1.43 ppm. and (2H, CH2, 3JHH 8 Hz) quadruplet at 4.34 ppm. The protons of the CH group of the imide cycle (2H, CH=CH) appear as a singlet at 7.11 ppm. Keywords: ultrasound, ethyl ether p-aminobenzoic acid, maleic anhydride, cyclization.

Examinations of the Matrix Isolation Infrared Spectra of Organic Compounds: PART XIII

1989 ◽  
Vol 43 (2) ◽  
pp. 305-310 ◽  
Author(s):  
W. M. Coleman ◽  
Bert M. Gordon
Keyword(s):  
Ir Spectra ◽  
Organic Compounds ◽  
Matrix Isolation ◽  
Intramolecular Hydrogen Bonding ◽  
Double Bond Position ◽  
Absorption Bands ◽  
The Matrix ◽  
Carbon Substitution ◽  
Ft Ir ◽  
Intramolecular Hydrogen

Matrix isolation Fourier transform infrared (MI/FT-IR) spectra have been collected on a series of internal alkenes, a series of hydroxy-substituted ketones, and a series of hydroxy-substituted esters. Assignments of double bond position and geometry are possible in the alkenes, due to the resolution of absorption bands of very similar energies. The location of the absorption bands for the alkenes was found to be very similar to the values found for the vapor-phase and condensed-phase spectra. Multiple carbonyl absorptions have been found in the MI/FT-IR spectra of the hydroxy ketones and hydroxy esters. Trends in the multiplicity of the carbonyl absorption patterns for these compounds as a function of ring size and hydroxyl carbon substitution have been used to document the presence of extensive intramolecular hydrogen bonding. The argon matrix as a phase for the study of stable organic compounds has, again, with this information, been shown to be unique.

Analysis of the characteristic absorption bands of the stretching vibrations of the lactone carbonyl groups in IR spectra of natural pseudoguaianolides

1990 ◽  
Vol 26 (2) ◽  
pp. 216-217
Author(s):  
�. L. Kristallovich ◽  
I. D. Sham'yanov ◽  
A. Ovezdurdyev ◽  
B. A. Akyev ◽  
M. R. Yagudaev ◽  
...  
Keyword(s):  
Ir Spectra ◽  
Carbonyl Groups ◽  
Absorption Bands ◽  
Characteristic Absorption ◽  
Lactone Carbonyl ◽  
Stretching Vibrations

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 ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Ir Spectra ◽  
Azeotropic Distillation ◽  
Synthesis Temperature ◽  
Side Reactions ◽  
Absorption Bands ◽  
Formation Reaction ◽  
Viscous Liquids ◽  
Urethane Formation ◽  
Product Control

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).

IDENTIFICATION OF COFFEE BEANS USING FTIR-SPECTROSCOPY AND MULTIVARIATE ANALYSIS

2021 ◽  
Author(s):  
Д.А. МЕТЛЕНКИН ◽  
Ю.Т. ПЛАТОВ ◽  
Р.А. ПЛАТОВА ◽  
А.Е. РУБЦОВ ◽  
А.М. МИХАЙЛОВА
Keyword(s):  
Multivariate Analysis ◽  
Discriminant Analysis ◽  
Ir Spectra ◽  
Ftir Spectroscopy ◽  
Spectral Data ◽  
Calibration Model ◽  
Absorption Bands ◽  
Coffee Beans ◽  
The Matrix ◽  
Decaffeinated Coffee

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.

IR spectra of powder hematite: effects of particle size and shape

Clay Minerals ◽  
1981 ◽  
Vol 16 (4) ◽  
pp. 375-382 ◽  
Author(s):  
Jose L. Rendon ◽  
Carlos J. Serna
Keyword(s):  
Particle Size ◽  
Ir Spectra ◽  
Ir Absorption ◽  
Surface Mode ◽  
Absorption Bands ◽  
Size And Shape ◽  
Ir Absorption Spectra ◽  
Theoretical Predictions ◽  
Particle Size And Shape ◽  
Average Size

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.

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