METHODS OF ANALYSIS OF SUBSTANCES SYNTHESIZED VIA ETHYLENE TELOMERIZATION REACTION

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METHODS OF ANALYSIS OF SUBSTANCES SYNTHESIZED VIA

ETHYLENE TELOMERIZATION REACTION

S.Z.Khudayberganova

Sh.Y.Bolibekova

A.G.Kalibekova

Tashkent State Technical University

https://doi.org/10.5281/zenodo.15718610

Annotation

This scientific work explores the synthesis of isopropyl and isoamyl

alcohols via telomerization of ethylene with methanol under high-pressure
hermetic reactor conditions. Various analytical methods including IR
spectroscopy, chromatographic-mass spectrometry, Raman spectroscopy,
physicochemical, quantum chemical, and mathematical modeling were used to
study and identify the structure and properties of the synthesized compounds.
The analysis included the determination of boiling point, density, refractive
index, and molecular refraction. IR spectra were obtained using the “INVENIO-S
FTIR” spectrometer, and Raman spectra were recorded with the “InVia Raman
BRAVO” device. Chromato-mass analysis was conducted using the Agilent MSD
5975C-GC7890A spectrometer. Quantum chemical calculations were performed
via HyperChem Professional software, while mathematical modeling and
experimental data processing were conducted using Maple 2018, applying the
method of least squares. Density was determined using pycnometers, and
refractive indices were measured by an Abbe refractometer.

Keywords

Ethylene telomerization, isopropyl alcohol, isoamyl alcohol, IR

spectroscopy, Raman spectroscopy, chromatographic-mass spectrometry,
quantum chemical modeling, mathematical modeling, refractive index,
molecular refraction, physical properties.

In the scientific research, IR spectroscopy, chromatographic-mass

spectrometry, Raman spectroscopy, physicochemical, quantum chemical, and
mathematical modeling methods were used. The structure and composition of
the products obtained through chemical synthesis processes were studied and
analyzed. Chromatographic-mass spectra were obtained in the liquid phase
using a standard HP-5MS column on an “Agilent MSD 5975C-GC7890A”
chromatograph-mass spectrometer, operating in the temperature range from
0 °C to 320 °C, with initial heating from 50 °C to 120 °C. In the chromatographic-
mass spectrum of the synthesized isopropanol, ions corresponding to the

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molecular mass of the compound and fragment ions resulting from
decomposition were identified.

The IR spectra of the synthesized compounds were obtained using the

“INVENIO-S FTIR” spectrometer, manufactured by Bruker in 2021, which has an
optical spectral resolution of less than 0.25 cm⁻¹ and operates within the IR
spectral range of 4000–400 cm⁻¹.

The Raman spectra of the compounds were recorded using the “InVia

Raman spectrometer BRAVO.” This spectrometer is particularly suitable for
identifying specific features of compounds, such as molecular “fingerprints,” and
for observing the state, tension, and deformation changes in molecular bonds.
During analysis, the laser beam was focused on sample areas with a diameter of
10 µm to determine volume.

Quantum chemical calculations are among the physicochemical research

methods used to evaluate the geometry of molecules, calculate the stability of
intermediates and transition states, and determine the properties of complex
organic compounds. The chemical properties and reactivity of molecules depend
on their electronic structure and energetic characteristics. Within the scope of
the dissertation, quantum chemical calculations were conducted using the
“HyperChem Professional” software to study the formation energy, total energy,
heat of formation, electronic energy, electron density distribution, nuclear
energy, dipole moment, and possible reaction pathways of both the initial and
synthesized substances.

Mathematical modeling of the process and processing of experimental

data

– Mathematical modeling and data processing methods make it possible to

identify chemical reaction processes in a short time and optimize them, enabling
modern design with minimal cost and time. The synthesis processes of isopropyl
and isoamyl alcohols were mathematically modeled and their experimental data
processed using the least squares method in the Maple 2018 software.

Determination of density.

In chemical industry laboratories and

pharmaceutical plants, pycnometers are typically used along with hydrometers
for technical analyses. Density is one of the indicators used in various industrial
facilities to determine the quality of liquid substances. It helps verify whether
the properties of raw materials and finished products comply with established
standards.

Before starting the analysis with the pycnometer, it was thoroughly rinsed

with a chromic acid mixture, followed by distilled water. First, the clean and dry
pycnometer was weighed on an analytical balance. Then, both the glass vessel

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and distilled water were heated to the same temperature at which the density of
the studied liquid was to be measured. The distilled water was poured into the
empty pycnometer up to the calibration mark on its neck. After that, the mass of
the pycnometer with water was measured. Then, the water was poured out, and
the measuring device was dried in a special oven. Isopropyl alcohol was poured
into the prepared glass vessel up to the same calibration mark. The temperature
was kept identical to that during the water filling. Finally, the pycnometer was
weighed again.

The density of isoamyl alcohol was also determined using the same method

by measuring the masses of the pycnometer filled with water and the
pycnometer filled with isoamyl alcohol.

In the final stage, calculations were performed using the following formula.

Given that the density of water at 20 °C is 0.9982 g/cm³, the relative density is
calculated using the formula below:

𝑑

4

20

=

𝑚

𝑊

∗ 0,998230

m

– the mass of the substance in the pycnometer at 20 °C;

W

– the mass of an equal volume of water at the same temperature (20 °C).

Boiling point.

The boiling point of liquid organic compounds is used to

determine their purity and to separate them. This can be performed using a
distillation apparatus. For the distillation, 75 ml of isopropyl alcohol was poured
into a 100 ml flask equipped with a thermometer and heated on an electric
heater.
Boiling point of isopropanol: T_boil(isopropanol) = 82.4 °C
The boiling point of isoamyl alcohol was determined using the same method:
T_boil(isoamyl alcohol) = 132 °C

Refractive Index and Molecular Refraction.

These properties are used to

determine the purity of liquid compounds. The change in direction of light as it
passes from one medium to another is called refraction. The incident ray, the
refracted ray, and the perpendicular drawn to the point of incidence at the
boundary of the two media lie in the same plane. If the angle of incidence is
denoted by α and the angle of refraction by β, then the ratio of the sine of the
angle of incidence to the sine of the angle of refraction is a constant value for the
two media:

sin α / sin β = C₁ / C₂ = n

C₁

and

C₂

are the speeds of light in the first and second media respectively;

n

is the constant for the two media and is called the refractive index.

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Air is usually considered as the first medium. The refractive index depends

on temperature and dispersion. An increase in temperature by 1 °C typically
reduces

the

refractive

index

by

approximately

0.0004.

The refractive indices of the synthesized organic compounds were determined
using an Abbe refractometer.

Procedure for measurement:

First, the prism block is opened, then a drop

of the liquid sample is placed on the lower prism using a pipette, after which the
prism block is closed. The refractometer is positioned so that adequate light falls
on the viewing area. The main adjustment screw is turned until part of the visual
field becomes dark. The compensator of the refractometer is adjusted until the
boundary line is clearly visible and aligns precisely with the central crosshairs in
the eyepiece. The reading shown on the refractometer scale is recorded. To
verify the reliability of the measurement, the process is repeated several times.
The surfaces of the refractometer prisms are first cleaned with a damp cloth and
then dried with cotton.

After determining the refractive indices and densities of the substances, the

molecular refraction (R_M) values are calculated using the Lorentz–
Lorenz formula.

𝑹

𝑴

=

𝒏

𝟐

− 𝟏

𝒏

𝟐

+ 𝟏

·

𝑴

𝒅

M

– molecular weight;

d

– density of the substance.

Molecular (or specific) refraction

represents the polarizability of all

electrons in a molecule. Molecular refraction does not depend on temperature,
pressure,

or

the

physical

state

(phase)

of

the

substance.

Refraction is considered an additive physical property, meaning that the
molecular refraction of a compound is equal to the sum of the refractions of the
atoms that constitute the molecule.

The methods for synthesizing isopropyl and isoamyl alcohols via the

telomerization reaction of ethylene with methanol are presented. The synthesis
was conducted in a hermetically sealed reactor operating under high pressure.
Methods for determining the physical properties—such as boiling point, density,
refractive index, and molecular refraction—of the synthesized compounds are
provided. To determine the molecular structure of the synthesized compounds,
Raman spectroscopy, IR spectroscopy, and chromatographic-mass spectrometry
methods were used. For mathematical modeling of the process and analysis of
experimental data, the Maple 2018 software was applied.

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