US2236811A - Alkylation of phenols - Google Patents

Description

Patented Apr. 1, 1 941 UNITED" STATES PATENT OFFICE ALKYLATION OF PHENOLS Charles G. Dryer, Chicago, 111., assignor to Universal Oil Products Company, Chicago, lllg, a

corporation of Delaware No Drawing. Application April 28, i938, Serial 310.2,905

3 Claims.

I to prepare, recourse is frequently had to the use of crude phenolic liquors which are produced from the distillation of hydrocarbon materials such as wood, coal and ligni-te, and also to the crude tar acids separable I therefrom by treatment with alkalis and later acidification. Since the effectivenms of these semi-refined products is dependent primarily upon the effectiveness of the phenolic compounds which they contain and since these inhibitors are diluted with hydrocarbon and rcn reactions involving polymerization and condensation reactions involving unsaturated hydrocarbons and other compounds which result in the formation of heavy dark-colored tarry and resinous materials which are moreor less insoluble in hydrocarbons and which'impart color. or cloudiness to gasolines even when the tars are used in small amounts ot-the order 010.1 ,When, however, a minor percentage oi boric acid is added to sulfuric acid of approximately 96% concentration to produce an alkyla-ting catalyst mixture, these side-reactions are minimized and alkylation proceeds as the principalreaction 'sothat the other compoundsoi a relatively-inert character,

it is necessary in practice to employ only those fractions which contain inhibiting compounds of outstanding potency as otherwise the amount 0! crude tar which needs to be added will be so great that the color of gasolines or other compounds to which they are added may be adan'ected. In extreme cases undesirable odors may be imparted.

While i'ew fixed and invariable rules have been evolved as to the relation between structure and inhibiting efl'ectiveness even in the case of deflnlte groups oi compounds such as phenols and amino-phenols mentioned, there are few exceptions to the rule that the addition of alkyl groups to the ring hydrogens tends generally to increase oil solubility and decrease water solubility and reactivity with alkalis. The present invention is a contribution to the art of improving the inhibiting value of crude phenol-containing products.

Inone specific embodiment the present invention comprises treatment or crude phenol-contars to improve the inhibiting value thereof by subjecting said tars to treatment with oleilnic hydrocarbons in the presence of catalysts consisting of sulfuric acid containing boric acid. I have determined that the Phenolic compoimds in crude tars may be alkylated by oleilns in the presenceol relatively concentrated sulfuric acid which contains arelatively small amount 01' boric acid without experiencing the adverse eflects observed when boric acid is absent. When strong sulfuric acid is employed as an alkylation catalyst it is commonly observed that there are side phenolic compounds can be improvedv in their inhibiting characteristics without rendering the total tar inapplicable to the treatment of gasoline.

The process of treating the crude tars with olefins in the presence or the preferred catalysts involves only relatively simple operations. A tar fraction is mixed with approximately. 15% by weight of concentrated sulfuric acid containing about 10% of boric acid at slightly elevated temperatures 01 the order of F. and olefins are gradually added-until the desired degree of alkylation is eflected. As a rule it is not necessary to use olefins of higher molecular weight than octenes and sufliciently good improvements in inhibiting potency are obtainable by utilizing the olefin-containing gas fractions produced in the cracking of petroleum as wiil be shown in later examples, these gas mixtures being introduced into the well-stirred mixture of acid catalyst and tar until the desired degree of alkylation has been accomplished.

In treating crude phenol-containing tars ac- I cording to the process of the present invention one eflective method of contacting which may be applied to continuous operation consists in i'orcibly injecting normally gaseous olefins or olefincontaining vapors, acid catalyst and tar into mixing devices positioned inside the top 01' filled columns, theemulsion produced being allowed to trickle downwardly over the filling: material to complete the initiated reactions, all reaction products being withdrawn from the bottom of the tower and separated into a lower liquid layer comprising partially spent acid catalyst,anupperliquid layercomprising the treated tar fraction and any residual fixed gases. In case the olefinic content 01' gas separated at this point is still high enough for further reaction, the gases may be recycled. Furthermore, the acid layer may be continuously f re-used until its effectiveness drops below a prac-f tical minimum. The treated tar may be then subjected to distillation to produce separate inc-'- tions of varying inhibiting value. using vacuum as a general rule to prevent thermal decomposition reactions.

on account of the complex character of the reactions which must necessarily be involved when tars of complex composition are treated, it is impossible to follow the exact course of the reactions which take place and there may be other effects than those due to alkylation of both phenols and other inhibiting substances such as, for example, phenolic ethers; however, beneficial effects have been uniformly observed in the inhibiting effectiveness of various tars and reliance is placed upon the observed results rather than any specific reaction which may occur.

It should be apparent to those familiar with inhibitors and the principles of organic chemistry that the exact effects of treating different crude tars with different oleflns or olefin-containing mixtures in the presence of catalysts are not exactly predictable on account of the complex character of the tars and the number of olefins which may be employed for the alkylation of their inhibiting constituents. It is therefore not to be presumed that the effects of treating various tars by the present process are uniform or exactly predictable since some will respond better to treatment than others. As will be shown in later examples, fractions which are too low in inhibiting value to be used are frequently improved sumciently so that their use is practical and in other cases there is only a slight improvement which is not sufficient to warrant the practical application of the process. It is presumed that preliminary tests will be conducted upon different tars to which the process may be applied to determine whether they are capable of sufficient improvement to warrant the application of the process.

The following examples are given to indicate the value of the invention in connection with the treatment of various tars although as already stated, the invention is of broad scope and the examples are not introduced with the intent oi imposing specific limitations thereon.

Example I A fraction of a lignite tar boiling within the range of 185-230 C. was intimately mixed with by weight of 96% sulfuric acid containing 10% of boric acid and the mixture was maintained at a temperature of 120 F. while a butanebutylene fraction produced in the fractionation of a cracked gas mixture was introduced until there was a gain of in weight. The process was then stopped and the acid layer separated from the oily products which were then washed with water and sodium carbonate and mildly heated under vacuum to remove water. The flnal yield of distilled tar was 137% of the original.

The original and the treated tar fraction were each used to treat a gasoline produced by cracking a paraflinic oil, this gasoline showing an induction period in the oxygen bomb test of 146 minutes. The addition of the 0.01% of the original lignite tar distillate raised the induction period to 205 minutes. The use of the same quantity of alkylated product raised the induction period to 275 minutes. It will thus be seen that there was not only a gain in weight of inhibiting fraction but also that the inhibiting value was also raised. Multiplying the percentage increase in weight by the increase in inhibiting potency gives a factor of 2.9 which may be designated as the "inhibitor quotient."

Example II In this case a fraction of lignite tar boiling from 200 to 300 C. was treated in the presence of the same catalyst with a butane-butylene fraction to a 53% gain in weight. After separation of the acid catalyst, washing and distillation, it was found that the yield of inhibitor was In this instance the inhibiting value as measured by the increase in induction period in the oxygen bomb was the same as the original and the value of til-re treatment was evident by the increase in yiel In both of the preceding examples the solubility of the fraction in gasoline was markedly increased and the resistance to removal by accidental water or aqueous alkali contact was found to be reduced.

I claim as my invention:

1. A process for alkylating phenols which comprises reacting the same with an olefin in the presence of sulfuric acid containing a small amount of boric acid.

2. A process for alkylating phenols which com- 7 prises reacting the same with an olefin in the presence of concentrated sulfuric acid containing about 10% by weight of boric acid.

3. A process for alkylating phenols which comprises reacting the same with a normally gaseous olefin in the presence of sulfuric acid containing a small amount of boric acid.

CHARLES G. DRYER.