Engineering Commons^™

Understanding The Photodegradation Mechanism Of Gaseous Acetaldehyde Over Bi2wo6 – Modified Znwo4 Photocatalyst Under Uv Light Irradiation, Mirabbos Hojamberdiev, Ronald Vargas, Shahlo Daminova, Zuhra Kadirova

CHEMISTRY AND CHEMICAL ENGINEERING

Indoor air quality has a significant impact on human health as people spend more time indoors. As a common indoor air pollutant, acetaldehyde is considered toxic when exposed to it for a prolonged period. The aim of this study is the enhancement of the photocatalytic activity of ZnWO₄ with a monoclinic wolframite structure for degradation of gaseous acetaldehyde by modifying its surface with Bi₂WO₆ layered structure. The mechanisms behind the enhanced photocatalytic activity and the pathways for acetaldehyde photodegradation over the Bi₂WO₆-modified ZnWO₄ photocatalyst are discussed.

Modelling Of Reаctive Distillаtion Process For Etherificаtion Reаction, Adham Norkobilov, Olimjon Mаksudov, Abdulaziz Bаkhtiyorov, Orifjon Zаripov, Abbos Elmаnov

CHEMISTRY AND CHEMICAL ENGINEERING

А reаctive distillаtion system is exаmined to produce for the production of Ethyl tert butyl ether (ETBE) viа etherificаtion of isobutene with ethаnol. Optimizаtion methods using heаt integrаtion аre аlso conducted. The molаr reflux rаtio аnd reboiler duty аre cаlculаted using sensitivity аnаlysis. The bottom streаm with the sаtisfied purity of ETBE is integrаted for heаting the feed streаm to the column. Heаt integrаtion from reаctor heаt to the initiаl feed streаm аnd from bottom streаm of the column to the column inlet streаm with the purpose of аchieving tаrget feed temperаture leаds to high conversion in the reаctive distillаtion …

Study Of Various Quality Characteristics Of Polyester Fibers Obtained On The Basis Of Primary And Secondary Polyethylene Terephthalate, Samida Ernzarova, Asror Juraev, Muzaffar Alimukhamedov, Farhod Magrupov

CHEMISTRY AND CHEMICAL ENGINEERING

The aim of study is comprehensive determination of various quality characteristics of polyester fibers obtained on the basis of primary and secondary polyethylene terephthalate. The analysis of the raw material base of pre-oriented yarns (POY) threads has been carried out. The technological, physicomechanical properties, as well as the structure of the primary and secondary polyethylene terephthalate used in the production of the threads have been studied. The structure and properties of polyethylene terephthalate changed: the properties were worse, the structure were amorphous, the molecular weight decreased. The structure of recycled polyethylene terephthalate changed as a result of technological conversions in …

Мulti-Layer Fibrous Material Based On Textile Waste, Sevara Alimkhanova, Nodir Mirzaev, Adham Rafikov

CHEMISTRY AND CHEMICAL ENGINEERING

At the textile and sewing and knitting enterprises of the Republic of Uzbekistan, the number of which increases every year, a sufficient amount of technological waste is accumulated, which formed in the processes of sizing yarn, starting and setting up equipment, designing and sewing products. Meanwhile, there is a shortage of warm, comfortable, light, soft lining materials for clothes and shoes based on natural raw materials. With the purpose of rational use of textile waste - shredded, disheveled scraps of fabric and knitwear, a multilayer nonwoven material for details of clothing and footwear has been obtained. The material formed by …

Spectral Features And Hydrogen Bond Structure Of Aqueous Solutions Of Ethanol, Dilbar Bozorova, Shukur Gofurov, Mavlonbek Ziyayev, Abdulmutallib Kokhkharov, Oksana Ismailova

CHEMISTRY AND CHEMICAL ENGINEERING

The aim of this work is develop an approach that makes it possible to study the spectral properties and structure of intermolecular hydrogen bonds in aqueous solutions of ethanol formed in systems whose existence in a gaseous medium or an isolated state is practically impossible. This approach bases on the combined use of infrared spectroscopy and molecular dynamics (MD) methods. An analysis give the structural reorganization of water molecules depending on the concentration of ethanol alcohol. It has been shown that the method of molecular dynamics with classical force fields makes it possible to explicitly take into account the molecules …

Determination Of The Stability Of Complex Compounds Of Copper (Ii), Zinc (Ii), Cadmium (Ii) And Silver (I) With Covalently Immobilized Sulfur Contain Ligands, Sherzod Kasimov, Khayit Turaev, Abdulakhat Jalilov, Farkhod Narmuratov, Zulkhumor Jumayeva

CHEMISTRY AND CHEMICAL ENGINEERING

The purpose of this study is to determine the stability of the obtained coordination compounds of some d-metals with covalent immobilized sulfur-containing ligands. To achieve this goal, coordination compounds of copper (II), zinc (II), cadmium (II) and silver (I) ions with covalent immobilized sulfur-containing ligands - О,О-di- (2-aminoethyl) -dithiophosphate potassium - polyester matrix (KD2AEDTP-PEM), O,O-di- (2-aminoethyl) -dithiophosphate potassium - carbamide-formaldehyde matrix (KD2AEDTP-KFM). Studies were carried out to determine the acid-base properties of covalent-immobilized sulfur-containing ligands - KD2AEDTP-PEM, KD2AEDTP-KFM and the concentration stability of the obtained coordination compounds with ions of copper (II), zinc (II), cadmium (II), and silver (I). Based …

Synthesis And Spectroscopic Study Of Complex Compounds Mn(Ii), Co(Ii), Cu(Ii) And Zn With 5-Amino-2-Mercaptobenzimidazole, Lobar Gapurova, Dilnoza Rakhmonova, Shakhnoza Kadirova

CHEMISTRY AND CHEMICAL ENGINEERING

The aim of this work is to study the effect of the nature of electron-donor and electron-withdrawing substituents in the molecules of heterocyclic ligands, the nature of acidoligands and transition metal ions on the properties of the synthesized coordination compounds. A method for the synthesis of new complex compounds of Mn (II), Cо (II), Cu (II) and Zn with 5-amino-2-mercaptobenzimidazole has been developed and the composition and structure of the synthesized complex compounds have been studied using modern physicochemical methods, such as elemental, thermogravimetric, X-ray phase analysis and IR spectroscopy. Coordination competing donor centers, electronic and geometric structures of the …

Resistance Of Polystyrol Concrete To Dynamic Impact Loads, Natalya Dubovitskaya, Zamira Mukhamedbaeva, Abduvali Mukhamedbaev

CHEMISTRY AND CHEMICAL ENGINEERING

The aim of the study is to increase the resistance of polystyrene concrete obtained from recycled polystyrene to dynamic shock loads. The issues of resistance of polystyrene concrete to compression forces with increasing load are considered. It was found that in terms of impact resistance, polystyrene concrete can be classified as a viscous material capable of absorbing high energy of shock loads. It has been determined that when Na₂SO₄ is introduced as a hardening accelerator, polystyrene concrete samples can absorb an impact energy of more than 178.5 J.

Features Of The Formation Of The Coating Structure On Titanium-Based Alloys, Uchkun Rakhimov, Nasiba Abduraimova, Yulbarskhon Mansurov

CHEMISTRY AND CHEMICAL ENGINEERING

Previously shown that coatings formed on titanium by plasma electrolytic oxidation (PEO) in an electrolyte with zirconium sulfate Zr(SO₄)₂ consisted of ZrO₂ and TiO₂ oxides, their surface layer is enriched with zirconium, they have good protective properties in chlorine-containing media. The resulting layers have a fairly regular distribution of relatively small pores, with a diameter of about 1 μm or less, on the surface. The composition and structure of PEO layers depend on both the composition of the electrolyte and the modes of formation. It is of scientific and practical interest to elucidate the effect …

Rotary Furnace Lining To Reduce Thermal Stress, Zamira Mukhamedbaeva, Erkin Kurbanov, Abduvali Mukhamedbaev

CHEMISTRY AND CHEMICAL ENGINEERING

The aim of the study is to reduce the thermal stresses of the lining in the areas adjacent to the flare sintering zone of rotary kilns intended for the production of cement clinker. It is proposed to use a lining made of parallel rows of alternating chamotte and chromium-magnesite refractory products to reduce thermal stresses in the areas adjacent to the flare sintering zone by up to 20%, increase the service life of the lining by 1.1-1.2 times as a result of equalizing thermal stresses in the areas of the sintering zone. Optimization of the initial raw material mixture, in …

Computer Simulation Of Particle Velocity In A Cyclone, Askar Artikov, Botir Usmonov, Dilshod Karabaev, Anvar Ulmasbaev, Lola Akabirova

CHEMISTRY AND CHEMICAL ENGINEERING

The article sets the goal of determining and calculating the speed of accelerated movement of particles in the gas-dust flow of an air cyclone, depending on the size of the cyclone, the physical properties of the particle and the gas-dust flow. A method for constructing a computer model of the motion of a particle in a roaring gas-dust flow of a cyclone is presented. The sequence of formalization of the computer model of the process of sedimentation of particles of a gas-dust flow of a cyclone unit is based on the theoretical foundations of aerodynamics and touches on the most …

Anti-Corrosion Protection Of Metal Parts Of Transportation Equipment With A Polymer Coating Based On Epoxiurethane, Aida Barkhanadjyan, Ravshan Khakimov, Botir Ibragimov, Oybek Vafayev, Dmitriy Ayrapetov

CHEMISTRY AND CHEMICAL ENGINEERING

Automotive vehicles are constantly exposed to corrosion processes, and the durability of metal parts depends on the intensity of corrosion. The loss of metals from corrosion is 8-10% of the initial metal mass. In total, losses from corrosion are 4-6% of national income in many countries. This indicates the need for research and the importance of scientific and technical work in this area. This can be achieved by developing a technology for producing anticorrosive compounds and applying them as protective coatings. The anticorrosive protection of a coating synthesized on the basis of local raw materials - epoxyurethane with an additive …

Synthesis And Research Of Silicon-Containing Phthalocyanine, Dilmurod Shukurov, Hayit Turayev, Abdulakhat Djalilov, Masud Karimov

CHEMISTRY AND CHEMICAL ENGINEERING

The aim of this study is to synthesize, and study a new form of dye based on phthalocyanine, a silicon-containing phthalocyanine pigment used as a dye for dye-sensitive solar cells, which are currently third generation solar cells as one of the energy source alternatives. To achieve this goal, a silicon-containing phthalocyanine pigment containing urea, phthalic anhydride and sodium fluorosilicate was synthesized and studied. Based on the results of IR spectroscopy, the reaction of pigment formation is proposed and the data of scanning electron microscopy is presented. Its differential thermal analysis, photodynamic analysis and its relationship with inorganic and organic solvents …

Development Of The Composition Of A Composite Material Based On Thermoreactive Binder Ed-20, Umida Ziyamukhamedova, Gavhar Miradullayeva, Erkin Rakhmatov, Jasur Nafasov, Mavtuna Inogamova

CHEMISTRY AND CHEMICAL ENGINEERING

The aim of the study is to determine the effect of the type of structural modifier and filler on the structure formation and technological properties of potting composite polymeric materials (HCPM) and protective coatings for sheet and complex-configuration technological equipment, taking into account their rheological properties. Compositions of composite polymer materials based on a thermosetting binder of epoxy-diane resin ED-20 filled with a mineral filler - kaolin modified with gassipol resin (GS) - were developed using Newton's interpolation formula and the Lagrange method. The optimal amount of gossypol resin determined in the composition of the composite – in the amount …

Effect Of Talc On The Properties Of A Compound Based On Ethylene-Propylene Copolymer, Ikromjon Usmanov, Farrukh Kurbanbekov, Bobir Aykhodjaev, Ravshan Adilov

CHEMISTRY AND CHEMICAL ENGINEERING

The aim of the research is to study the possibility of replacing Korean-made talc with inexpensive talc from an Afghan deposit, processed in Uzbekistan and used for the production of polypropylene compounds. In the future, these compounds are used for the manufacture of plastic car parts. A block copolymer produced by Uz Kor Gaz Chemical was chosen as a binder. For this, the influence of the content and type of talc on the properties of a compound based on an ethylene-propylene copolymer was studied.

The properties of the obtained compounds checked using ISO standards. The fractional composition of the studied …

Influence Of Sulfur Modification On The Properties Of Sulfur Concrete, Zhavkhar Khayitova, Khasan Beknazarov, Hayit Turaev, Abdulakhat Jalilov

CHEMISTRY AND CHEMICAL ENGINEERING

The purpose of this study is the synthesis and study of modified sulfur concrete for use in industrial construction. To achieve this goal, sulfur concrete based on gossypol resin and pyrolysis distillate was modified and studied. The strength properties of sulfur-based concrete obtained from sulfur modified with gossypol resin and pyrolysis distillate were investigated. For the addition to sulfur concrete, industrial waste was used as a finely dispersed filler - fly ash from the Angren TPP and phosphogypsum generated at Ammophos-Maxam JSC. It was found that the best strength results correspond to sulfur-based concrete modified with gossypol resin using an …

Physical And Chemical Studies Of Overroof Rocks Of Clay Shales Of The Dzherdanak Deposit, Mastura Aripova, Ivan Levitskiy, Khabiba Khamidova, Odelbek Ammanov

CHEMISTRY AND CHEMICAL ENGINEERING

The purpose of this study is study of the physical and chemical properties of the overburden of the Dzherdanak deposit. The chemical and mineralogical composition of the overburden of the Djerdanak deposit has been studied by the methods of X-ray and thermography, electron microscopy and infrared spectroscopy. The main phases are quartz, kaolinite and muscovite. The study of the fine structure of the rock under an electron microscope showed the homogeneity of the rock with pronounced uniform inclusions, which is preserved even after firing. Changes in the rock after firing at 1050 °C have been determined. The formation of mullite …

On The Possibility Of Obtaining Effective Phosphoric Fertilizers As A Result Of Interaction Of Phosphorite-Containing Waste With Activated Glauconite Sands, Nargisa Takhirova, Fazlidin Khudoyberdiev, Shahlo Daminova

CHEMISTRY AND CHEMICAL ENGINEERING

These studies are devoted to the study of the chemical properties obtained as a result of chemical activation of glauconite and further neutralization of activated glauconite by waste products of phosphorite concentrates. Based on the results of X-ray structural studies of the obtained products, it is possible to obtain granular complex fertilizers after adding phosphorites to the system. Activation with mineral acids (nitric or sulfuric) should be carried out to accelerate the transformation of minerals from glauconite sands into an easily digestible form. Since the obtained compounds form an acidic environment, it is necessary to neutralize them. The neutralization process …

Study Of Sorption Of Rhenium Ions On Solid Extragents, Otabek Pardaev, Dildora Ilkhomjonkizi Khakimboeva, Shahlo Daminova, Ulugbek Sharafutdinov, Sharipov Khasan Turabovich

CHEMISTRY AND CHEMICAL ENGINEERING

In this work, the aim is to study the possibility of extracting rhenium from sulfuric acid solutions by sorption of impregnated sorbents based on polystyrene-divinylbenzene (MN202) and an organic reagent MAB (2-amino-1-methylbenzimidazole).New sorbent based on MN202 (Purolite) impregnated with organic reagents have been obtained and investigated. The sorbent characteristics determined using SEM, XRD and FTIR methods. The optimal conditions for the sorption of rhenium (VII) ions for the "element-sorbent" systems have been established. Under static conditions, the sorption of rhenium on impregnated sorbents in a sulfuric acid solution was studied in the periodic system with respect to the contact time, …

Synthesis Of Aromatic Acetylene Alcohols Using Complex Catalytic Systems, Odiljon Ziyadullaev, Guzal Otamukhamedova, Abduvakhab Ikramov, Saida Abdurakhmanova, Otabek Boytemirov

CHEMISTRY AND CHEMICAL ENGINEERING

Some cyclic ketones (cyclopentanone, cyclohexanone, 2-methylcyclohexanone, menthol, camphor and adamantanone) enantioselective alkynylation reactions with phenylacetylene have been studied in the presence of complex catalytic systems - Zn(OTf)₂/NЕt₃/MeCN, 3,3′-Ph₂BINOL-2Li/TGF and BuLi/KO^tBu/TGF. Synthesis were performed new aromatic acetylene alcohols – 1-(2-phenylathinyl) cyclopentanol (1), 1-(2-phenylethinyl)cyclohexanol (2), 2-methyl-1-(2-phenylethinyl)cyclohexanol (3), 2-isopropyl-5-methyl-1-(2-phenylethinyl)cyclohexanol (4), 1,7,7,-trimethyl-2-(2-phenylethinyl)bicyclo [2.2.1] heptanol-2 (5) and 2-phenylethinyltricyclo [3,3,1.0^3,7]nonanol-2 (6). Synthesis reactions of aromatic acetylene alcohols, activation energies were determined, kinetic of chemical changes and reaction mechanisms were proposed. The course of the reactions and the effect of the selected ketone molecule size, structure and …

Heterogeneous Catalytic Conversions Of Acetylene, Abduvakhab Ikramov, Sevara Kholikova, Noryigit Musulmanov

CHEMISTRY AND CHEMICAL ENGINEERING

The reactions of interaction of acetylene with water vapor, acetic acid and ammonia in the presence of heterogeneous catalysts have investigated. Depending on the nature of the starting components used, acetaldehyde and acetone, vinyl acetate, pyridine bases and pyrrole synthesized. Heterogeneous catalysts selected for each studied reaction based on some scientific prerequisites for the selection of catalysts. Active catalysts for the investigated reactions were determined, which contain compounds of cadmium, zinc, bismuth, chromium, iron and copper, in general, d-group metals. γ-Al₂O₃, bentonite and kaolin used as a catalyst carrier. Hydrofluoric acid, acetic acid, ammonium fluoride and …

Composite Elastomer Materials Based On New Ingredients, Akhmadjon Ibadullaev, Elmira Teshabaeva, Murodjon Vapaev

CHEMISTRY AND CHEMICAL ENGINEERING

The results of a study present the effect of new modified ingredients on the complex of properties of composite elastomeric materials. Methods for modifying mineral fillers have developed. It found that the introduction of modified ingredients into the composition of elastomeric compositions enhances the interfacial interaction at the “rubber-filler” interface and the formation of additional bonds between rubber macromolecules and functional groups, resulting in an improvement in the complex of properties of the compositions. New accelerators, activators for vulcanization of rubbers and plasticizers with stabilizing properties have proposed, and their optimal contents in the composition have determined.

Composition For Protecting Technological Equipment Against Salt Deposits And Internal Corrosion, Hasan Kadirov, Sadritdin Turabdjanov

CHEMISTRY AND CHEMICAL ENGINEERING

Aimed studies on the synthesis of metal complexonates have carried out. The reaction of obtaining zincate zincate oxyethylene diphosphonic acid OEDP has studied. On the basis of synthesized zincate-OEDP, compositions of corrosion inhibitors and deposits of mineral salts with the addition of a vacuum residue of monoethanolamine (RMEA) and polyaminocrotanol (PKI-3), which are able to effectively suppress corrosion processes in environments with different initial corrosive activity, have been compiled. It is proved that the high efficiency of the composition OEDP : zincate-OEDP : PKI-3 (maximum protective effect - 97.9%) is much more effective than the composition OEDP : zincate-OEDP : …

Rational Disposal Of Pet Containing Waste And Prospects For The Synthesis Of New Polymers, Asror Juraev, Muzaffar Alimukhamedov, Ravshan Adilov, Farhod Magrupov

CHEMISTRY AND CHEMICAL ENGINEERING

As a result of the research on the utilization of polyethylene terephthalate-containing household waste, a promising direction was identified in the production of a new type of secondary polyethylene terephthalate (SPET) - unsaturated polyesters.It was revealed that the final product, which formed when the alcoholization process is complete in any proportion of of glycol and secondary polyethylene terephthalate, is the bisalkylent terephthalate of terephthalic acid; the content of the alcoholysis product consists of bisalkylent terephthalate, different molecule mass, functionally hydroxyl-containing complex polyester polyol and free diols.

The laws of alcoholization of secondary …

Layered Bismuth Tungstate: Heterogeneous Photocatalysis For Environmental Remediation, Mirabbos Hojamberdiev, Zuhra Kadirova, Shahlo Daminova, Khasan Sharipov, Nobuhiro Matsushita

CHEMISTRY AND CHEMICAL ENGINEERING

Air and water pollution has been one of the challenging environmental issues in modern society. Since the Honda-Fujishima effect was first reported in 1972, a semiconductor-based photocatalysis has been regarded as one of the most green and economical processes for potential application in environmental remediation. Bismuth-based semiconductors are regarded as a promising group of advanced photocatalytic materials due to their suitable band gap for visible light response, an increased mobility of photo-generated charge carriers because of well-dispersed Bi 6s orbital, non-toxicity, and easy tailoring of their morphologies. To utilize its full potential in environmental remediation, various studies have been carried …

Sorption-Spectrometric Determination Of Nickel By Monoammonium Salt Of Glycirrizic Acid, Ugilay Abdurakhmanova, Khabibjon Kushiev

CHEMISTRY AND CHEMICAL ENGINEERING

The aim of this work is to develop a sensitive, selective and rapid method for the determination of nickel ions using the monoammonium salt of glycyrrhizic acid as an analytical reagent. There obtained IR spectra of the nickel diglycyrrhizinate complex. A simple and express spectral method for determination of the nickel ion is presented. The optimal conditions for the determination of the nickel ion are found. Under optimal conditions, a gradual graph was drawn up, which is linear in the concentration range for nickel of 20.0–40.0 μg/25 ml, the composition of the complex of nickel with the monoammonium salt …

Features Of Chloridizing Roasting Of Almalyk Mining Metallurgical Combinate Wastes, Malokhat Atamuratova, Dildora Khakimboeva, Khasan Sharipov, Zuhra Kadirova, Tulkin Shakarov

CHEMISTRY AND CHEMICAL ENGINEERING

With the aim to develop a comprehensive technology for processing Almalyk Mining Metallurgical Combinate (AMMC) wastes, the influence of chloride additives on the copper and zinc chloride volatilization process is considered. The relationship between presence of the calcium, potassium and sodium chlorides chlorinating additive on the copper and zinc chlorides sublimation from the AGMK wastes at roasting temperatures up to 700-1000˚C was established.

The Role Of The 2,7-Dinitroso-1,8-Dihydroxynaphthalene-3,6-Disulfonic Acid Reagent In Determining The Thorium Ion (Iv), Nigora Qutlimurotova, Salohiddin Mahmadoliyev, Khabibullo Todjimukhamedov

CHEMISTRY AND CHEMICAL ENGINEERING

The aim is to develop a method for the amperometric determination of thorium (IV) ion with 2,7-dinitroso-1,8-dihydroxynaphthalene-3,6-disulfoxyl reagent. Methods of amperometric determination of thorium by solution of 2,7-dinitrozo-1,8-dihydroxynaphthalene-3,6-disulfonic acid on different acid-base properties of background electrolytes and buffer mixtures are considered. The half-wave potential of new reagent was found by logarithmic analysis equal 0.72 V at pH 2.82, which once again indicates on the irreversibility of the process of electrooxidation of the studied organic reagent in used acid-base medias. The conditions for amperometric titration of thorium are optimized, and the influence of outside accompanying metals on the shape of curves …

Synthesis Of Some N-Oxides Of Pyridylacethylene Amines Based On 2-Methyl-5-Ethynylpyridine, Abduvakhab Ikramov, Odiljon Ziyadullayev, Adkham Khamidjanov, Shavkat Bojariev, Davron Khandamov

CHEMISTRY AND CHEMICAL ENGINEERING

The aim of this work is to study the reaction of 2-methyl-5-ethynylpyridine N-oxide with some aliphatic and aromatic amines to obtain N-oxides of pyridylacetylenic amines. 2-Methyl-5-ethylpyridine converted to 2-methyl-5-vinylpyridine by dehydrogenation, and 2-methyl-5-ethynylpyridine obtained by bromination and dehydrobromination. 2-methyl-5-ethynylpyridine N-oxide synthesized by oxidation of 2-methyl-5-ethynylpyridine with perhydrol in acetic anhydride. The synthesis of N-oxides of pyridylacetylenic amines by the Mannich reaction carried out. The effect of the solvents: methanol, ethanol and n-dioxane, the catalyst, and the reaction time on the yield of the final product studied. The structure and composition of the synthesized PAA N-oxides were established using IR and …

The Role Of Hydrogen Bonds In Diluted Ethanol Solutions Of Cyclohexane And Dimethylformamide, Dilbar Bozorova, Shukur Gofurov, Mavlonbek Ziyayev, Dildora Mirtojiyeva, Odina Ismanova, Oksana Ismoilova

CHEMISTRY AND CHEMICAL ENGINEERING

The refractometric method and Fourier transform infrared spectroscopy were used to determine the optical features of the concentration characteristics of diluted ethanol solutions of cyclohexane and dimethylformamide. It was found for the first time that at some concentrations the hydrogen bond is stronger than for a pure ethanol solution. The first maximum of the excess refractive index of solutions is formed at a concentration of 0.02 mole fraction of cyclohexane and dimethylformamide, which is in good correlation with IR spectroscopy, indicating the largest number of formed hydrogen bonds.