United States Patent Office

Patented July 13, 1948 2,444,924 UNITED STATES PATENT OFFICE Ladislaus Guillaume Farkas and Ozjasz : schichter, Jerusalem, Palestine No Drawing. Application September 28, 1945, Se rial No. 619,256. In Palestine October 1, 1944 . 1. 16 Claims. (C. 260-495) . 2 This invention relates to the oxidation of alco- amount of the compound, to be oxidized, and an holic hydroxyl groups or of aldehyde groups. amount stoichiometrically corresponding to the More specifically, the invention is concerned with desired amount of oxidation product of an ox the oxidation of primary and secondary alkanols idizing agent, other than bromine, that is capa and alkanals, and of similar compounds... The 5 ble of oxidizing the bromide ion to elementary invention has more particularly as its object to bromine under reaction conditions. provide a convenient process for the prepara- As examples of oxidizing agents of the class tion by straight, non-disruptive oxidation of such referred to hereinbefore, we may employ com compounds as are not or only difficultly obtain- . pounds containing both halogen and oxygen able so far by other methods. 10. atoms, such as chlorine dioxide and other The terms "straight" and "non-disruptive". oxides, or chlorates, bromates, chlorites, bro used for the qualification of the term "oxida- mites, hypochlorites, perchlorates and perbro tion' are meant to restrict the invention to such mates of the alkalies, alkaline earths or other oxidation reactions as lead to the removal of metals or non-metals such as the above men hydrogen from the hydroxyl or aldehyde groups 15tioned salts of sodium, potassium, calcium, mag and/or to the addition thereto of oxygen without nesium, zinc or ammonium, or oxides of am the splitting-off of carbon atoms from the mole- photeric metals in valence states of at least +4, cule of the compound so treated, with the forma- such as dioxides of (chlorine) manganese or lead, tion of carboxyl or aldehyde groups from pri- chronic acid or its salts such as potassium. mary alcoholic hydroxyl group (the carboxylic. 20. chromate or bichromate, manganates or per acid so formed being usually esterified with the manganates of sodium, potassium calcium, mag starting alcohol present in excess), of keto groups : nesium, and other metals. Although these are from secondary hydroxyl groups, and of carboxyl - preferred, elementary chlorine, Or Oxygen, Or groups from aldehyde groups. ozone may also be employed. The straight, non-disruptive oidation of many 25 The bromine may be initially added to the re substances of the kind inquestion be car action mixture in elementary form or as abro ried out with a great variety of oxidizing agents. mide or hypobromite such as sodium, potassium However, in the great majority oknown proc- or calciuromide or hypobromite. If it is esses of this kind, the reaction is either not com plete, or too slow for practical performance for 30 toadded elementary as a bromide, bromine this bywill the at onceoxidizing be oxidized agent preparation purposes, or accompanied by unde- resent. and the el tary bromin l sired side reactions, usually of a disruptive char- pre a e elementary bronine originally acter. In particular it is known that chlorine added or thus produced, or the hypobromite, as can be used as an oxidizing agent for the con- the case may be, becomes active towards the version of alcohols into higher oxidized sub- compound to be oxidized, oxidizes a correspond stances, but usually the use of chlorine for this 35 ing amount thereof and is thereby reduced itself to bromide, and the cycle begins afresh. type of reactions entails the drawbacks stated Where a or te is used as an oxidizing agent above. In addition, the chlorine has a tendency P to enter the molecule of the compound to be and is gradually Converted into the bromide, the e pound to latter is produced in a theoretical yield. Since oxidizedtemperatures. as a substituent, particularly at elevated 40 bromate can easily be prepared in a highly pure It has now been found that the various draw- state, the bromide is correspondingly pure. This backs of known various oxidizing agents can be is especially remarkable in view of the difficul avoided and a virtually complete, smooth and ties encountered in the hitherto usual process of compoundsquickstraight, of the non-disruptive kind specified oxidationcan be obtained, of the derdensbonate another aspect, to a promide. particular Accordigy, embodiment of to the virtual exclusion of side reactions, if the the present invention can be defined as a process oxidation is carried out by means of oxidizing of preparing bromides of the highest degree of agents other than bromine in the presence of a purity, wherein a pure bromate is subjected to relatively small amount of elementary bromine. 50 reduction by the combined action of bromide ion Accordingly, this invention consists in a proc- and an organic substance, or a mixture of or ess of oxidizing compounds of the kind referred ganic substances, containing one or more pri to, wherein the oxidation is performed by the , mary and/or secondary alcoholic hydroxyl combined action of an amount of bromine groups and/or aldehyde groups. The bromate stoichiometrically small in proportion to the 55 employed in this case can be sodium, ammonium, 2,444,924 3 4. potassium, calcium, magnesium bronate or the When the bromine is released in the course of bromate of some other metal. the oxidation reaction from such bromine corn The process according to this invention may pounds as hydrogen bromide or copper bromide be carried out in the presence of a solvent capa it is preferred to use hydrogen bromide in an ble of dissolving with the oxidized reaction prod amount corresponding to 0.03 to 0.5 mole of bro uct. It is even possible, and sometime advan mide for each gram atom of available oxygen in tageous, to use as such solvent another portion the oxidizing agent. of the reaction product, whereby a more concen The process according to this invention has trated solution of the latter is obtained which is proved most suitable for the preparation, for ex easier to be separated and worked up. O ample, of esters. of various alcohols with the cor Materials that can be used as solvents may be responding acids, such as ethyl acetate or butyl hydrocarbons, halogenated hydrocarbons, acids, butyrate, or higher ones like hexyl caproate, lau esters, ethers, phenols and the like such as ben ry laurate and others for the corresponding al zene, chlorobenzene, acetic acid, propionic acid, cohols. From various secondary alcohols, the ethylacetate, butylether, phenol, cresol or xylenol. 5 corresponding ketones have been prepared. The reaction can be carried out at atmospheric Where the starting material contains both pri pressure, reduced pressure, for example at 10 mary and secondary alcoholic hydroxyl groups, to 300mm mercury pressure, or at Superat the oxidation of the secondary hydroxyl group mospheric pressure for example at one to ten at is in general far quicker than that of the pri mospheres. The proper pressure range can be mary one. Similarly, where a compound con conveniently adjusted to the required reaction 20 tains a hydroxyl group besides an aldehyde group, temperature when the reaction can be carried the oxidation of the latter is in general much out at the boiling point of the mixture under quicker than that of the former. This different refluxing conditions so that the reaction ten behaviour of different groups towards the oxi perature can be kept readily constant. 25 dizing agents can be utilized for conducting the The temperature of reaction ranges from about reaction in a desired direction in preference to 30° C. up to about 150° C., temperatures from any undesired oxidation within the same sys about 35 C. to about 80° C. being preferred. ten. It has been found, furthermore, that the oxi The invention is illustrated in the following dation reaction can be promoted by catalysts 30 examples to which it is, of course, not restricted. such as copper compounds, e.g., copper bronate; Where in the following, reference is made to molybdenum compounds, e.g., molybdena or so aqueous solutions of calcium bromate and of dium molybdate; and other compounds of cat hydrogen bromide, these are respectively of alytic metals such as those of the "transitional' 35.5% strength by Weight (12 moles per kg. of elements, which have their differentiating elec 35 solution) and 44% by weight. --- tron in the second from the outermost shell. A - Eacamaple 1 convenient periodic table showing this relation ship is shown in the Journal of Chemical Educa 288 grs. of ethyl alcohol of 96% strength (cor *tion, August 1939, page 394. The elements of responding to 6 moles) are mixed in an Erlen the first transitional series are those having 40 meyer fiask with 111 grs. of solid potassium bro atomic nuinbers of 21 to 30 inclusive, those of the mate (0.67 mole) and 32 grs. of elementary bro second transitional series are those having atomic mine (0.2 mole). The mixture is stirred. The numbers 39 to 48 inclusive; those of the third reaction which soon sets in is exothermic and transitional series are those having atomic num causes the mixture to heat. When a temper bers 57 and 72 to 80, inclusive; and those of the 45 ature of 50° C. is reached the flask is cooled and fourth transitional group which are now known, the mixture is kept at 50 C. for about 6 hours, the group being as yet incomplete, are those hav first by further cooling, later on by slight heat ing atomic numbers 89 to 92 inclusive. Exam ing.

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