Feb. 26, 1957 I 1. w. GROTE 2,783,124 METHOD OF MAKING DIHYDROXY ‘ALUMINUM CARBONATE COMPOUNDS‘ '

Filed Oct. 21, 19755 ‘

Ohn.O.inonOnn00»ON0d0-6'O-n0 . 2,783,124 States Patent 'icc Patented Feb. 26, 1957

2 present invention are preferably the aluminum alkoxides, such as aluminum isopropylate (tri-isopropoxide), but 2,783,124 other aluminum tri-alkoxides may be used in which the alkoxide groups are C2-C4 groups. These aluminum al METHOD OF MAKING DEHYDROXY ALUMINUM coholates are hydrolyzable in an alkaline aqueous medi~ CARBQNATE CDMPOUNDS um to form aluminum hydroxide or other aluminum lrvine W. Grote, Chattanooga, Tenn., assignor to The group containing at least two hydroxyl radicals, the other Chattanooga Medicine Company, Chattanooga, Tenn, valency of the aluminum being satis?ed by, possibly, an a corporation of Tennessee alkoxide radical. 10 The reaction involved in the case of the aluminum Application October 21, 1955, Serial No. 542,023 alcoholates is represented by the following equation:

11 Claims. (Cl. 23-14) (1) ‘ (ZHzO) . A1(OR)3 + M11003 ---> (H0)2A1o COzM+3ROH wherein R is a C2-C4 alkyl group and M is a monovalent This invention relates to a method of preparing di 15 radical of the class consisting of alkali metal and am hydroxy aluminum carbonate compounds, and more par monium radicals. It is probable, as before stated, that ticularly to a method of making dihydroxy aluminum the reaction involves an intermediate formation of di sodium, potassium, or ammonium carbonates. These are hydroxy aluminum alcoholate. This reaction is prefera true compounds having the generic structural formula bly carried out in the presence of equi-molar proportions hereinafter given. The compounds so obtained may be of the reactants, although the bicarbonate may be in used in forming lakes in dyeing processes. In particular, slight excess. The disadvantage of using any appreciable however, the dihydroxy aluminum sodium carbonate is excess of bicarbonate is that it tends to be absorbed or useful as an antacid, as more particularly described and occluded in the precipitate of the dihydroxy aluminum claimed in my copending application ?led of even date carbonate compound and must then be washed out in herewith. Serial No. 541,938, ?led October 21, 1955. 25 order to obtain the pure compound. Actually, only the It has heretofore been proposed, as in the Lowig Ger one reaction product, namely, the dihydroxy aluminum man Patent No. 19,784 of 1882, to prepare a carbonated alkali metal or ammonium carbonate, is formed, regard sodium aluminate or carbonated potassium aluminate by les of the excess of the bicarbonate used, thus con?rming the reaction between sodium aluminate and sodium bi the fact previously stated that this reaction leads to a carbonate or the corresponding potassium salts. Accord single true compound. The bicarbonate compound, ing to that patent, the reaction that takes place under being on the alkaline side itself, if present in at least equi the conditions speci?ed therein is exempli?ed by the fol molar proportions, maintains a ‘pH of at least 7, a condi lowing equation: tion that is favorable to the formation of the desired end product. 35 Another suitable source of the cationic aluminum The German patent explains that ‘the caustic alkali in _ group is aluminum hydroxide, itself, which is available an atmosphere charged with carbonic acid immediately in the form of a gel, dried or semi-dried, or compressed, is reconverted to bicarbonate and consequently is merely or in other water-reactive form. Any form of altuninum the carrier of the carbonic acid to the alkali aluminate. hydroxide can be used that is capable of providing the di The method of the present invention differs from that 40 or tri-hydroxy aluminum group in a reactive state when of the German patent in starting with an aluminum com dispersed in an aqueous medium at a pH of at least 7. pound in which the aluminum is cationic and in yielding The reaction between aluminum hydroxide and sodium a ?nal product that differs in structure from Lowig’s prod bicarbonate is shown by the following equation: not in respect to the location of the sodium atom. Fur thermore, the aluminum compound used as my starting 45 material is preferably a relatively water insoluble com The potassium and ammonium carbonates react in the pound capable upon hydrolysis in a basic medium of fur same manner as shown for sodium carbonate in-the above nishing aluminum groups containing at least 2 hydroxyl equation. Instead of starting with aluminum hydroxide, radicals, or of furnishing aluminum hydroxide,,Al(OI-l)3. it is possible, although not so satisfactory, to start with Aluminum alkoxides, or alcoholates, and aluminum hy 50 an aluminum acylate, such as aluminum acetate, basic droxide gels are examples of preferred starting materials aluminum acetate, aluminum aceto-tartrate, and the like, meeting these requirements. The other reactant is an or an inorganic aluminum salt, such as aluminum borate, alkali metal or ammonium bicarbonate. The reaction is bromate, bromide, chloride, and the like, and use such carried out in an aqueous medium under basic conditions an excess of the bicarbonate as not only to neutralize such that cationic aluminum groups associated with two 55 the acidic component of the aluminum compound select or more hydroxyl radicals are available for reaction with ed as the starting material but also to effect the formation the alkali metal or ammonium bicarbonate to give the of the intermediate di- or tri-hydroxy aluminum group desired end product, namely, a dihydroxy aluminum for further reaction with the bicarbonate to form the di alkali metal carbonate, or dihydroxy aluminum am hydroxy aluminum alkali metal or ammonium carbonate. monium carbonate. The principal objection to starting with the aluminum It is therefore an important object of this invention to acylates or inorganic aluminum salts is that a pure di provide a new method for the preparation of these di hydroxy aluminum alkali metal or ammonium carbonate hydroxy aluminum alkali metal or ammonium carbonate compound is more difficult to obtain. Furthermore, un compounds by reacting an aluminum compound of the less the conditions are such as to bring about the inter type referred to with the corresponding bicarbonate com 65 mediate formationv of the di- or tri-hydroxy aluminum pound, in the presence of water. ' group previously referred to, other water insoluble prod Other and further important objects of this invention ' ucts than the desired dihydroxy aluminum alkali metai will become apparent from the ‘following description and or ammonium carbonate are likely to be formed. It is appended claims. The drawing is a chart ‘of the speci?c therefore much simpler and greatly to be preferred to titration curve for dihydroxy aluminum sodium 70 start with an aluminum alcoholate or aluminum hy carbonate. - ‘ droxide as the source of the cationic aluminum group. The aluminum compounds used in the, method of my The aluminum compound and the bicarbonate that are 2,783,124

selected may be admixed dry and added to the water, corded with time. In this determination, the Fisher or they may be added separately, or they may be dissolved titrimeter was used with calomel and glass electrodes for separately and the solutions admixed. In reactions in pH determinations. The eye control was set using a volving the preferred starting materials, such as the alumi buffer solution of pH 3 made by mixing 0.1 molar citric num alcoholates and aluminum hydroxide, the bicar acid solution with 0.2 molar disodium phosphate solution bonate is preferably dissolved in water ?rst, and the in the proportion of 15.89 ml. to 4.11 ml. according to aluminum compound added to the resulting solution of Mcllvaines’ standard butler solution directions. The pH the bicarbonate. In reactions which are not extremely readings at 23 ° C. were as follows: fast or which require additional heat and/or agitation to proceed at a reasonable rate, there may not be too much 10 Time in minutes 1 l 2 1 advantage in having one or both of the reactants in solu tion before being brought into contact, since one of the 1.61 1.40 main advantages of putting the bicarbonate into solution 2.32 2. 00 3.10 2. 05 first is that this procedure tends to avoid precipitation of 3.30 3.12 the bicarbonate by occlusion or adsorption along with ...... 3.30 3 30 x30 the insoluble reaction product. In a preferred procedure, 3.30 3.51 the bicarbonate is dissolved in Water and the aluminum 3.30 3. 33 3. 30 32 alcoholate, in a. substantially pure form, is stirred there 3 30 :s. 31 into. A gelatinous precipitate forms very rapidly, but with time or continued stirring, is converted into a more 20 1 Specimens 1 and 2 were specimens 01' dihydroxy aluminum sodium granular and, therefore, a more easily ?ltered precipitate, carbonate prepared in accordance with the method of Example T, which may be readily separated from the aqueous rc It will be seen from the foregoing that under the condi inalnder ol‘ the reaction system. tions of the neutralization determination above set forth, The following examples show speci?c embodiments: the pH value rises to a pH of at least 3 within ?ve minutes 25 EXAMPLE I of the beginning of the test period and shortly thereafter reaches and stays at a pH of about 3.30 for the balance Sodium bicarbonate (168 gms, 2 moles) was dissolved of the thirty minute test period. in 1400 cc. of water in a 2 liter stainless steel beaker. Dihydroxy aluminum sodium carbonate, prepared as The solution temperature was adjusted to between 45 above described, is substantially amorphous, or at least and 50° C. Liquid aluminum isopropylate (ca. 408 gms, 30 is a very poorly crystallized substance. When tested for 2 moles) was added rapidly to the sodium bicarbonate index of refraction using the immersion method, the com solution in the beaker, with violent agitation. The usual pound is found to have only one aggregate index of re» addition time was about 1%. minutes. A stainless steel fraction, which was somewhere between 1.488 and 1.509. turbine type agitator was used and run at high speed. The reason for this broad index of refraction range is that The slurry was stirred for ten minutes and allowed to 35 the index of the same specimen varies when tested at stand over night. It was then ?ltered and the ?lter cake different times. dried to a moisture content of between 10 and 12%. The speci?c acid titration curve for dihydroxy alumi The following analytical results show a comparison num sodium carbonate is illustrated in the drawing by between the percentages calculated for the various com the solid line curve indicated by the reference numeral 10. ponents of dihydroxy aluminum sodium carbonate of the 40 The procedure for the speci?c acid titration is as follows: formula above given, and the percentages actually found The reagent used is hydrochloric acid which has been by analysis: adjusted as nearly as possible to a normality of 0.10 and Analytical results on dihydroxy aluminum sodium car accurately standardized. In the preparation of the sample, bonate of Example I the antacid material to be tested is dried to 10-12% 45 water content, the material ground to pass 100 mesh screen and then reduced to a ?ne powder with a mortar and Calculated Found pestle. A sample Weight in grams of exactly 10 times the normality of the standardized hydrochloric acid is 35.40 30.8 30.56 29. 59 used. For example, with 0.1015 N acid, a sample weight 1. 40 1. 48 50 59.69 53. 27 of 1.0150 grams would be used. This is done so that the 15.97 16.2 result will represent ml. of 0.1000 N acid/gram without Molecular weight ______. 144. 00 ______. _ any calculation. In the test, the accurately weighted sample is placed in Moisture ______“percent-” _ 11.0 a 200 ml. high form beaker and 25.0 ml. of distilled water pH water suspension ______9.70 55 are added. The pH at zero acid concentration is do Acid consuming power ______cc./gm__ 230 termined with the Beckman type “E” glass electrode Density ______gms./cc__ 2.144 standardized at pH 9.18 and 10.0. Appropriate quanti The moisture determination was made by heating di ties of standard acid solution are added to separate hydroxide aluminum sodium carbonate at 110° C. in samples so that the range from zero concentration oi‘ 60 vacuo over phosphorus pentoxide for two hours and de acid to 70 ml. acid/gram is covered with enough points termining the loss in weight. to draw a smooth curve connecting the points. This The pH of the water suspension of the compound was range is the signi?cant one for showing differences bc taken as the pH of a slurry of 1 gram of the ?nely pow tween the action of aluminum antacids. If it is desired to dered material in 25 ml. of distilled water. investigate the complete acid consuming power of the ant 65 acid, the range should be extended to 300 ml. cf The acid consuming power of the compound was deter acid/gram. The mixture is stirred vigorously for one mined by adding 0.25 gm. of the ?nely powdered material hour with a mechanical stirrer to give opportunity to to 75 ml. of 0.1~N hydrochloric acid. The solution was reach equilibrium. The pH is determined in this acid gently agitated for ten minutes and then back titrated range with the standard glass electrode standardized at pH with O. 1-N sodium hydroxide to a pH of 3.8. The acid 70 4.0 and 6.85. , consuming power is expressed as the ml. of 0.100-N The results of the test for speci?c acid titration char' hydrochloric acid consumed by a gram of the sample. acteristics of dihydroxy aluminum sodium carbonate are In order to determine its neutralization characteristics, illustrated in the graph of the pH versus ml. of 0.100 I‘! 30 mgs. of the compound of Example I were added to ‘ hydrochloric acid/ gram of sample. Curve 10 is the result 20 ml. 0.0l—N hydrochloric acid and the pH change re 76 of the points so plotted. greases 5 6 The corresponding potassium and ammonium com‘ showed strong adsorption by the dihydroxy aluminum pounds can be formed by the same procedure set forth sodium carbonate. ' in Example I, using equi-molzar proportions. In general, This is a continuation in-part of my applications Serial the potassium and ammonium compounds so produced Nos. 342,957 (now forfeited) and 400,822. have properties comparable to those of dihydroxy alumi I claim as my invention: num sodium carbonate, but the potassium and ammonium 1. A method of preparing a compound having in its compounds are not so suited for use as antacid material, anhydrous form the formula the potassium compound because potassium pharmaoeuti~ OH cals are not generally favored by the medical profession, Al-—0--CO OM and the ammonium compound ‘because insu?‘iciently stable 10 over long storage periods, OH wherein M is an monovalent radical selected from the EXAMPLE II group consisting of alkali metal and ammonium radicals, Reheis “F-1000” dried aluminum hydroxide gel (0.2 which comprises bringing together in an aqueous medium mole, 20.4 gms.) was thoroughly mixed with sodium bi 15 a cationic aluminum compound-selected from the group carbonate (0.2 mole, 16.8 gms.) and 100 cc. of 65° C. consisting of aluminum alcoholates in which the alkoxide water. The mixture was heated 2 hours in the'water bath group is a C2 to C4 group and aluminum'hydroxide and at 60-70“ C. It was then air dried over the weekend. at least an equimolar weight of a bicarbonate of the The cake was dried to a moisture content of betwee formula MHCOa to effect the precipitation of said com 10 and 15% by weight, ' 20 pound having the foregoing formula, and_‘ recovering said ‘V EXAMPLE III compound. , 2. The method of claim 1, wherein the cationic aiu~ Reheis aluminum hydroxide, compressed gel, “F-SOO”, minum compound is an aluminum alkoxide having C2 (0.2 mole, 102 gms.) was‘ mixed with sodium bicarbonate to Ca. in the alltoxide group. ‘ (0.2 mole, 16.8 gms.) and heated at 60—70° C. for 6 3. The method of claim 1, wherein the cationic alu hours. The dihydroxy aluminum sodium carbonate minum compound isaluminum isopropylate. formed as ‘a precipitate was allowed to stand over night 4. The method of claim 1, wherein the cationic alu~ and was then ?ltered. It was air dried to a moisture con minum compound is aluminum hydroxide. tent or“. between 10 and 15 % by weight. ' 5. The method of claim 1, wherein the cationic alu ‘The corresponding potassium and ammonium carbon 30 minum compound is an aluminum hydroxide gel. ates can be substituted for the sodium carbonate of Ex 6. The method of preparing dihydroxy aluminum amples II and III, using equi-molar proportions, and the sodium carbonate, which comprises bringing together an reaction will proceed with the formation of the corre aluminum alkoxide in which the alkoxide group is a sponding dihydroxy aluminum potassium carbonate or di‘ C2-C4 group and at least an equi-molar weight of sodium hydroxy aluminum ammonium carbonate. 35 bicarbonate in aqueous solution to obtain a precipitate Theoretically, the dihydroxy aluminum sodium carbon and recovering said precipitate. ate and the corresponding potassium and ammonium. 7. The method of preparing dihydroxy aluminum carbonates should be water soluble. However, they are sodium carbonate, which comprises bringing together practically insoluble in water, being soluble to the extent aluminum isopropylateand at least an equi-molar weight of only a few thousandths of a percent. This obviously 40 of sodium bicarbonate in aqueous solution to obtain a means that the compounds exist as insoluble complexes. precipitate and recovering said precipitate. Washings and prolonged treatment with water will, of 8. The method of preparing dihydroxy aluminum po course, alter the surface of the complexes and eventually tassium carbonate, which comprises bringing together an result in their break down to form aluminum hydroxide. aluminum alkoxide in which the alkoxide- group is a As formed by the reactions given above and without pro 45 C2-C4 group and at least an equimolar weight of potas longed treatment with water, these complexes can be iso sium bicarbonate in aqueous solution to obtain a precipi lated and dried to recover them as compounds of the tate and recovering said precipitate. formulae above given. 9. The method of preparing dihydroxy aluminum am The extremely low solubility of the complexes, how monium carbonate, which comprises bringing together ever, indicates that they may be polymers, such as repre 50 an aluminum alkoxide in which the allcoxide group is a sented by the formula: C2-C4 group and at least an equimolar weight of am HO monium bicarbonate in aqueous solution to obtain a Al-O-COOMJNHIO precipitate and recovering said precipitate. > 10. The method of preparing dihydroxy aluminum HO 1 65 potassium carbonate, which comprises bringing together wherein n is zero or a small integer, and x is an unknown aluminum isopropylate and at least an equi-molar weight integer. No method is known for determining the value ofpotassium bicarbonate in aqueous solution to obtain of x. a precipitate and recovering said precipitate. In order to determine the ability of dihydroxy alumi 11. The method of preparing dihydroxy aluminum num sodium carbonate to form lakes, or dye complexes, 60 ammonium carbonate, which comprises bringing together successive samples of equal weight of that compound were aluminum isopropylate and at least an equi-molar weight mixed with similar volumes of various dye solutions, the I of ammonium bicarbonate in aqueous solution to obtain mixtures allowed ‘to stand 10 minutes and then?ltered a. precipitate and recovering said precipitate. and the ?lter cakes washed with equal volumes of water until the ?ltrate was free of non-adsorbed dye. Of the No references cited. dyes employed, eosin, erythrosine and logwocd extract all 65