PROCEEDINGS
OF THE TOMSK POLYTECHNIC INSTITUTE
OF THE ORDER OF THE OCTOBER REVOLUTION
AND THE ORDER OF THE RED BANNER OF LABOR
NAMED AFTER S. M. KIROV

Volume 253
1976

GAS-CHROMATOGRAPHIC ANALYSIS OF ALCOHOLS AND ACIDS OF THE FATTY SERIES

S. I. SMOLYANINOV, A. V. KRAVTSOV, I. V. GONCHAROV

(Presented by the Scientific-Methodological Seminar of the KhTF)

One possible method for obtaining fatty alcohols may be the synthesis from carbon monoxide and water vapor proposed by Kelbslem and co-workers [1]. The synthesis product is a complex mixture of hydrocarbons and oxygen-containing compounds. It is very tempting to select process conditions such that the synthesis is directed toward the formation predominantly of oxygen-containing compounds.

For a quantitative assessment of the influence of external conditions, a rapid and sufficiently accurate method for analyzing the reaction product is needed. These requirements are met by the method of gas chromatography.

Gas-chromatographic analysis of hydrocarbons presents no particular difficulty and can be carried out by one of the many methods described in the literature [2, 3]. Chromatography of acids and alcohols is a much more complicated task, and therefore the aim of the present study was to develop a procedure for the chromatographic analysis of fatty alcohols and acids.

The difficulty of separating acids and alcohols is due to their high tendency to form hydrogen bonds with the solid support. For this reason, the peaks on the chromatogram are asymmetrical and broadened. To reduce the “tailing” effect, a polar liquid phase and an acidic additive are used.

The work was carried out on a universal gas chromatograph “Khrom-2,” equipped with a flame-ionization detector.

In addition to phases described in the literature (Tween-80 [8], Carbowax 20M [5], polyethylene glycol adipate [6]), substances not previously used for this purpose were tested, such as butter and the polyester of aldehydic acid and glycerin.

The best results were obtained when using butter as the liquid phase, deposited on Celite-545 in an amount of 1.6% of the weight of the support. Adipic acid, in an amount of 0.8% relative to the weight of the support, served as the acidic additive.

Selection of separation conditions was carried out on artificial mixtures of alcohols and acids. It proved impossible to find conditions under which separation of a mixture of alcohols \(C_1—C_9\), with a temperature interval of \(64—230^\circ\text{C}\), would be possible; therefore the analysis was performed at two temperatures.

On a packed column 160 cm long and with an internal diameter of 6 mm, at a temperature of \(140^\circ\text{C}\) and a carrier-gas pressure of \(0.88\ \text{kg}/\text{cm}^2\), it was achiev-

gave satisfactory separation of alcohols \(C_4\)–\(C_9\). The lower alcohols \(C_1\)–\(C_3\) emerged as a single peak. Their separation was carried out on a capillary column 50 m long and with an internal diameter of 0.2 mm at a temperature of \(110^\circ\mathrm{C}\), a pressure of \(0.92\ \mathrm{kg/cm^2}\), and a flow rate of \(0.12\ \mathrm{l/min}\). The acids \(C_2\)–\(C_7\) were separated on a packed column at a temperature of \(140^\circ\mathrm{C}\) and a carrier-gas pressure of \(0.84\ \mathrm{kg/cm^2}\).

Quantitative calculation of chromatograms was carried out by the internal-normalization method. Recalculation of the concentration of alcohols analyzed on the capillary column was carried out according to the relationship we proposed

\[ P_i = P_b \frac{h_i \cdot l_i \cdot K_i}{h_b \cdot l_b \cdot K_b} \cdot 100, \]

where \(P_i\) is the concentration of the component on the capillary column;
\(h_i, l_i, K_i\) are its height, retention distance, and calibration coefficient;
\(h_b \cdot l_b \cdot K_b\) are the height, retention distance, and calibration coefficient for butyl alcohol, obtained on the capillary column;
\(P_b\) is the concentration of butanol obtained on the packed column.

Analysis of mixtures with known concentration confirmed the correctness of applying the proposed relationship.

Thus, on the basis of the work performed, the following conclusions may be drawn.

1. A new liquid phase has been found for the separation of fatty acids and alcohols, and its ratio with the solid support and the acid additive has been selected.

2. The analysis conditions have been determined.

3. A relationship has been proposed that makes it possible to carry out quantitative calculation of chromatograms by the internal-normalization method in a multistage analysis scheme.

REFERENCES

1. H. Kolbel und E. Vorwerk, Brennstoff Chemie, 38, 4283, 1957.
2. K. Brenner, V. Coates, Nature, 181, 1401, 1958.
3. M. Nelson, W. Hines, Anal. Chem., 32, 110, 1960.
4. E. M. Emery, W. Koerner, Anal. Chem., 35, 647, 1963.
5. R. Baker, J. Chromatogr., 4, 418, 1966. (Cited in Referativnyi Zhurnal Khimiya, 14 G 181, 1967)
6. A. K. Appleby, J. Chromatogr., 5, 211, 1967. (Cited in Referativnyi Zhurnal Khimiya, 22 G 168, 1968)