Research of the synthesis of new acetylene aminoalcohols

. The article describes the synthesis of acetylene amino alcohols based on secondary acetylene alcohol and amino compounds containing a hydroxyl group, the results of scientific research and their analysis to study the influence of factors such as temperature and catalyst on the yield of the product in the process. In the course of the work, a new type of acetylene amino alcohol was obtained with high efficiency as a result of the condensation reaction of ethanolamine (or diethanolamine) with hex-1-yn-3-ol mediated by formaldehyde. Optimal conditions for carrying out synthesis processes have been determined. The mechanism of these chemical processes is explained on the basis of theoretical quantum chemical calculations of the reactivity of the starting substances.


Introduction
Currently, functional derivatives of acetylene hydrocarbons are widely used in the chemical and petrochemical industries, medicine and pharmaceuticals, agriculture, machinery as semifinished products, corrosion inhibitors and biologically active preparations.In this regard, the development and improvement of technologies and methods for the synthesis of acetylene alcohols, amines and amino alcohols, acetylene acids and oxyacids are considered topical issues.
A lot of research is carried out in the world on the basis of acetylene derivatives to carry out synthesis, study the properties and use of biologically active compounds with high reactivity, which contain various functional groups.[1][2][3][4][5][6][7].
While the literature provides the results of a number of scientific studies on the synthesis of acetylene amino alcohols, methods for obtaining products based on secondary acetylene alcohols and saturated amino alcohols have been little studied.

Research methods
The work studied the processes of aminomethylation of secondary acetylene alcohol gex-1yn-3-ol by the Mannich reaction using monoethanolamine or diethanolamine, as well as the effect of temperature, reaction duration and catalyst on the performance of the product in these processes.Paraformaldehyde was used as a methylating agent in this process [6][7][8][9].Synthesis of aminomethylation based on hex-1-yn-3-ol, paraformaldehyde and monoethanolamine was carried out according to the following scheme (scheme 1).
The aminomethylation process based on hex-1-yn-3-ol, paraformaldehyde and monoethanolamine was carried out according to the following scheme (scheme 2).

Synthesis of amino alcohols
The four-necked flask with a capacity of 500 ml is equipped with a reverse refrigerator, a drip funnel, a thermometer and a mechanical stirrer.0.2 moles of hex-1-yn-3-ol, 0.2 moles of dry paraform, 150 ml of dioxane and 0.05 g of copper (I) chloride powder as a catalyst were placed in the flask.The reaction mixture was heated at 80-100 °C and 0.2 mol of monoethanolamine was added drop by drop for 30 minutes.Then the reaction mixture was heated at 90-100 °C for 4-5 hours with active stirring.After stopping the process , the mixture of reaction products was left at room temperature for 12 hours [10][11][12].
The next day, the reaction mixture was transferred to a separation funnel with a capacity of 1000 ml, decantated using 200 ml of chloroform to separate the organic layer.This process was repeated three times.The organic part is first distilled at normal atmospheric pressure at 60-80 °C and separated from chloroform, then divided into components under vacuum.
The resulting acetylene amino alcohol was purified from various additives using a system selected by column chromatography.
The process of synthesis of acetylene amino alcohol based on hex-1-yn-3-ol, paraform and diethanolamine was also carried out according to the above method.
Based on the results of the research work carried out, it can be said that with an increase in the mixing time from 180 minutes to 420 minutes, the yield of acetylene amino alcohol increases from 22.8% to 52.2%.When the temperature rises from 80 °C to 95 °C, the yield of acetylene amino alcohol increases from 36.0% to 54.4%.
These synthesized acetylene amino alcohols are highly soluble in polar solvents such as water, alcohol, acetone, chloroform, carbon tetrachloride, poorly soluble in nonpolar solvents such as benzene, hexane.

Results and discussion
Based on the results of the research work carried out, it can be said that with an increase in the mixing time from 180 minutes to 420 minutes, the yield of acetylene amino alcohol increases from 22.8% to 52.2%.When the temperature rises from 80 °C to 95 °C, the yield of acetylene amino alcohol increases from 36.0% to 62.7%.It was also noticed that in the synthesis of acetylene amino alcohol based on diethanolamine, the yield of the product is higher than the yield of acetylene amino alcohol based on monoethanolamine.
The reason for the relatively low performance of the product in the reaction of monoethanolamine with hex-1-yn-3-ol is explained by the following.Hex-1-yn-3-ol is exchanged with formaldehyde for one hydrogen atom of the amino group (-NH 2 ) in the monoethanolamine molecule to form 1-(2-hydroxyethylamino)heptyne-4-ol. Part of the resulting compound can again interact with hexyne-1-ol through formaldehyde due to the hydrogen of the imine group (-NH-) in its molecule.This leads to a decrease in fertility of 1-(2-hydroxyethylamino)heptyne-4-ol.The results obtained are shown in Tables 1, 2. In the synthesis of acetylene amino alcohols based on secondary acetylene alcohols, the dependence of the reaction direction on the atomic charge distribution in the starting substance acetylene alcohol was calculated by theoretical quantum chemical methods.The results obtained by quantum chemical calculations are presented in Figures 1-2.As can be seen from the above figure, the charge of the O(5) atom in the hex-1-in-3-ol molecule is -0.347 eV, and it is the most reactive active center in the molecule.However, as a result of the fact that the copper(I) chloride catalyst (copper(I) ion) forms a -complex with an acetylene bond, the most reactive active center becomes the carbon atom of the (4) methine group (charge -0.143 eV).As a result, the mobility of the hydrogen atom attached to this carbon atom increases and its exchange becomes easier.Since the charge of the nitrogen atom in monoethanolamine is -0.262 eV, according to the Mannich reaction, the amino group is a reactively active center, and the hydrogen atoms attached to this nitrogen atom are mobile.Due to this, the methylene group of formaldehyde is alternately replaced by these hydrogen atoms.

Conclusion
The synthesis of acetylene amino alcohols with high yields was carried out on the basis of secondary acetylene alcohol -hex-1-yn-3-ol, formaldehyde and monoethanolamine or diethanolamines.With the help of physical research methods, some physicochemical constants, composition and structure of the obtained acetylene amino alcohols were determined.
In the course of the research work, the active centers and reactivity of the starting substances were studied using modern computer programs, on the basis of which the directions of the reactions were theoretically determined.Using an experimental method, the influence of factors such as catalyst, temperature, reaction time on the synthesis processes and product performance was studied.Optimal conditions for the synthesis processes were selected.
It was found that this process takes place in a medium of dioxane and a catalyst from a copper (I) chloride salt.Instead of a general conclusion, we can say that new acetylene amino alcohols were synthesized by the Mannich reaction and the reaction mechanisms were studied.

Fig. 2 .
Fig. 2. Spatial structure and charge distribution of the monoethanolamine molecule.

Table 1 .
The effect of temperature and reaction duration on the yield of the product in the synthesis of 1-(2-hydroxyethylamino)hept-2-yn-4-ol.