Patented May 29, 1945 2,377,038 w UNITED STATES PATENT OFFICE MANUFACTURE OF PERACDS Joseph S. Reichert, Samuel A. McNeight, and Arthur A. Elston, Niagara Falls, N. Y., assign ors to E. I. du Pont de Nemours & Company, Wilmington, Del, a corporation of Delaware No Drawing. Application September 15, 1941, Serial No. 410,878 6 Claims. (C. 260-502) This invention relates to a new and improved ods require the use of peroxide solutions having process for the preparation of peracids and their active oxygen concentrations equivalent to at salts, and to the novel peracids and persalts re least 7 volumes if satisfactory yields of peracids . Sulting therefrom. More particularly, it relates are to be obtained. The temperature under which to a new and improved method for the prepara the reaction proceeds is also of considerable in tion of the organic peracids, particularly the portance in these methods, and it has generally monoperacids, and the salts of these acids in been necessary to maintain an unusually low aqueous solutions of relatively dilute concentra temperature. These disadvantages have restrict tion. This application is, in part, a continuation ed the use of such methods, both because the of our copending application Serial No. 317,318, handling of peroxide solutions of high concentra filed February 5, 1940. tion may be inconvenient, as well as because of The organic peracids constitute a class of acids the necessity for cooling or otherwise controlling which are chemically characterized by the pres the temperature of the reaction mixture. Our ence of the perhydroxyl grouping OOH as part improved procedure makes it possible to prepare of the molecule. They may be regarded as de peracid solutions from peroxide solutions of rela rived from other acids by replacing the hydroxyl tively low active oxygen concentrations, concen group containing the ionizable hydrogen atom of trations of from 0.006 to 7.0 volumes, although it Said acids by the perhydroxyl group OOH. Thus, may also be employed effectively for manufac monoperSuccinic acid has the chemical constitu turing organic peracid and persalt Solutions of tion 20 as high as 12.5 volumes. Rigorous control of the CH2COOOH temperature under which the reaction proceeds &H cooh is avoided, and by suitable control of the pH we have found it possible to prepare peracids and and may be regarded as derived from succinic persalts in high yields at temperatures ranging acid, 25 anywhere from 15° C. to 90° C. CHCOOH In referring to the concentration of a Solution CHCOOH of a peroxygen compound, such as alkali metal by replacing a hydroxyl group containing an ion peroxide, hydrogen peroxide, sodium perborate, izable hydrogen atom with the perhydroxyl group. etc., or in referring to the concentration of an The invention with which this application is 30 aqueous solution of a peracid or persalt, it is especially concerned involves a process for pre usual in the art to refer to "volume concentra paring Solutions of Organic peracids or their salts, tion.' The volume concentration of such an more particularly aqueous Solutions of mono aqueous solution is the number of Volumes of peracids and the alkali-forming salts of the oxygen gas, measured at 0° C. and 760 mm, of monoperacids, by reacting an acid anhydride with 35 mercury pressure, that would be released upon an inorganic peroxide or peroxygen compound Complete decomposition from One Volume of the under conditions wherein the pH of the resulting solution measured at 20° C. There is, of course, peracid or persalt solution is carefully controlled, a definite correlation between the actual concen so as to fall within certain limits. As the in 40 tration of the solution and the volume concentra organic peroxide or percompound, ordinarily we tion, depending on the particular oxidizing agent prefer to utilize hydrogen peroxide or sodium involved. Thus a solution of hydrogen peroxide peroxide, and We have found that the peracids of 100 volumes concentration, a Solution Solid gen and their salts are produced in very satisfactory erally for commercial use under the trade-mark yields in the dilute solutions that we are espe 45 name “Albone,' for example, contains at least cially interested in preparing when the reaction 27.6% H2O2 by weight. is carried out under controlled conditions. In adueous solution the organic peracids and 'Methods previously employed for preparing the salts of these peracids, particularly their peracids have involved either reacting acid an alkali-forming salts, are full equivalents of each hydrides with solutions of hydrogen peroxide 5 other. As far as the utility of the Solution of the which were acidic in reaction at ordinary room Oxidizing agent is concerned, it makes little dif temperatures or temperatures below room tem ference whether the peracid radical is part of the peratures, or reacting them with strongly alkaline acid or of the salt of the acid. In any given peroxide Solutions at temperatures below 10° C. Solution the relative amounts of organic peracid and preferably below 0°C. These known meth 55 and salt of this peracid depend generally upon 2 2,877,088 the pH of the solution. In view of the full equiv Such as benzene Sulfonic acid and naphthalene alency between the organic peracids and persalts, sulfonic acid. Among heterocyclic acids, nicotinic it is usual to use the term “peracid' generically acid, quinolinic acid, and furoic acid are also to include not only the acids themselves, but their compounds from which peracids may be derived. salts, particularly the alkali-forming salts. Else In fact, any organic peracid such as, for ex where throughout this specification and the ap ample, in addition to the acids previously men pended claims this procedure will be adopted, the tioned, perpropionic acid, monopercrotonic acid, term "peracid' or “peracids' including the salts monoperadipic acid, persulfobenzoic acid, non Of these acids. - Opernaphthalic acid, and the peracids derived AS previously stated, the peracids may be gen 0 from acid anhydrides by the Diels-Alder diene erally regarded as derived from acids by replace Synthesis Such as those prepared from maleic an ment of one or more of the hydroxyl groups con hydride with cyclopentadiene, butadiene, benzene, taining an ionizable hydrogen atom by the per terpenes and rosin hydrocarbons, and derivatives hydroxyl group OOH. A typical example is mon of naphthoquinoline, pyridine and heterocyclic Opersuccinic acid, which may be generally re hydrocarbons may be prepared by our improved garded as derived from succinic acid. Other ex method. Among organic acids containing no car amples of organic monoperacids which can be boxyl groups which may be regarded as base acids manufactured in high yields in relatively dilute . from which peracids are derivable by the previ solution. Without the necessity for controlling the ously noted substitution, we may include phos temperature, in accordance with our improved 20 phonic acids, the corresponding peracids being process, include peracetic acid, monoperphthalic capable of manufacture by our improved method. acid, monopermaleic acid, monoperglutaric acid, In accordance With our improved process, solu and monoperterephthalic acid. In addition to tions of peracids or their salts are prepared by such monoperacids derived from organic acids reacting an organic acid anhydride and a solution containing One or more carboxyl groups, there are of a peroxygen compound of the desired concen of course monoperacids derived by the introduc tration, the alkali content of the solution being so tion of a perhydsoxyl group into other classes of adjusted that the peracids formed during the re organic acids. Thus, monoperacids which may be action are partly or completely neutralized. prepared in accordance With our process include When a peroxide solution, such as a solution of those derived by introducing a perhydroxyl group 30 Sodium peroxide or hydrogen peroxide, is utilized in place of the hydroxyl group containing the as the peroxygen compound, the reaction is car ionizable hydrogen atom of a hydroxy organic ried out by preparing a peroxide solution of the acid. Peracids may in this way be derived from desired concentration. The alkali content of this all classes of Saturated and unsaturated acids, Solution is then so adjusted that the peracids and Whether the acids be aliphatic or aromatic. Other acids subsequently formed, upon the addition of organic acids not characterized by the presence the organic acid anhydride, are partly or com of a carboxyl group, such as the Sulfonic acids, pletely neutralized. Generally an equimolar either aliphatic or aromatic, may be regarded as amount of the Selected organic acid anhydride base acids from which peracids capable of manu is dissolved in the alkaline peroxide solution, facture by means of our improved method may be 40 Whereupon the reaction proceeds to form the de derived by the substitution previously noted. sired peracid or persalt. Peracids may also be derived from heterocyclic We have found that by suitable adjustment of compounds such as furoic acid. While our inven the alkali content of the solution of the peroxygen tion is directed to the manufacture primarily of compound reacted with the anhydride, solutions the organic monoperacids, under certain circum of peracids may be formed at temperatures rang. stances our process may be used to form diper ing from 15° C. to 90° C. and with active oxygen acids and, even under certain circumstances, tri concentrations ranging from 0.006 volume to 12.5 peracids. volumes. In all cases satisfactory yields of per Among aliphatic organic acids from Which acid or persalt are secured. This process con Inonoperacids may be regarded as derived, which 50 stitutes a distinct improvement as far as prepar monoperacids may be prepared in accordance with ing peracid Solutions of these low concentrations our improved process, We may mention both mon is concerned, since previous methods for prepar obasic acids, of which acetic acid is an example, ing such Solutions, particularly solutions of con as well as dibasic acids, of which succinic acid is centration ranging from 0.006 volume to 7.0 vol an example.