10. Application of CCP in inhibitors synthesis for styrene produce

The approaches to inhibiting process for pyrocondensates and individual monomers are rather different. For example, as a rule for the inhibiting of thermo-polymerization of liquid products of pyrolysis, it is necessary to apply individual compounds as inhibitors, for example, TBPC or ionol, whereas for the prevention of undesirable polymerization of individual monomers, such as styrene, for example, it is advisable to use more effective so-called "inhibiting compositions."

It is known [8] that the phenol oligomer, obtained by phenol formaldehyde condensation, manifests rather low effectiveness as inhibitor in the production process of styrene, so it means that all production processes of phenol modifications for obtaining inhibitors are considerably different. For example, a method of acid-oxidative condensation of CCP to obtain effective coinhibitor for the process of styrene distilation has been developed by us [9]. Chemical modification of CCP to give "modificated phenol co-inhibitor" (MPC) is the synthesis one-pot reaction by the subsequent treatment of the substrate with catalytic amounts of concentrated sulfuric acid at heating up to 95°C for 1 h, then the hot acidic phenol solution is treated with hydrogen peroxide in the presence of catalyst that is iron (II) sulfate for 1 h, and thereafter the oxidate is cooled and neutralized with sodium nitrite at room temperature. The phenol oxidate is extracted with alkyl acetate, and the solution obtained is employed for the inhibiting of styrene thermo-polymerization. The estimation of the efficiency is made by thermal processing of pure styrene in the standard conditions at heating to 120 ± 1.5°C, with the blowing of nitrogen under stirring for 2.5 h. The amount of the polymer formed is detected by sedimentation of the styrene probe (2 sm<sup>3</sup> ) from autoclave and its dilution with ethyl alcohol (8 sm<sup>3</sup> ) and then centrifugation and separation of the sediment, the latter's drying and weighting according to the State Standard RU 10003-90.

The results of the experiments with different inhibiting compositions of styrene thermo-polymerizations are presented in Table 8.

It is clear from Table 8 that neither itself MPC nor itself MB (Mannich Base - 2,6-di-tert-butyl-4 dimethyl-aminometyl phenol, N,N'-dimethyl(3,5-di-tert-butyl-4-oxybenzyl)amine) (entry 2) possess satisfactory inhibiting properties, but their compositions "MCP + MB" in different combinations are rather competitive in comparison with the best known inhibitors, and they could be recommended as inhibitors for the styrene production.

Accordingly, the task-oriented chemical modification of coke phenols could solve the very complicated ecological proble the utilization of toxic technogeneous phenols transforming them into competitive reagents for petrochemical industry, namely high effective phenolic inhibitors of polymerization.

Chemical modification of phenols in this line could be realized by other methods, for example, by the reaction of SHP with bulky bi- and tricyclic substituents, for example, diisobornylphenols [2] and diadamantylphenols [9], or by the generation of the so-called inhibiting systems employing phenols, solvent, and turpentine [10]. That is another subject for investigations.


\*IPON - Russian analog Nalco inhibitor on base nitroxilyc radicals \*\*DOQ - Quinone-dioxime; PNP - p-nitro-phenol; АНМ - isobutyl-2,4-dinitro-phenol

Table 8. Comparative effect of PFR produced from phenols of different stock reservoirs at the consumption of 0.03% mass.
