INDUSTRIAL AND ENGINEERING CHEMISTRY
periquidcentwasformic acid and refluxed 4.5 hours. The resulting steam-distilled exactly as in the previous run. The
distillate was caught in two fractions. Each fraction was hydrolyaed, dried, and analyzed separately. The results are given in Table 1. DETERMINATION OF STANDARDS OF PURITY.I n order to compare the products purified by this method with commercial dimethylanilines obtainable on the open market, the Zerewitinoff method of analysis was applied to two such samples. Analysis was also made of a so-called c. P. grade, the specifications Of Which read (IFree from Monomethy'aniline." All samples were thoroughly dried by the procedure already described:
% Commercial sample 1 Commercial sample 2 c. P . grade
2.1 1.8 1 .o
Literature Cited (1) Hibbert, H . , and Sudborough, J. J.,J. Chem. Sor. (London) Proc., 20, 165 (1904). (2)-Wallach, O., and Wusten, M., Ber., 16, 145 (1883). (3) Zerewitinoff, Th.,Ibid.,40, 2023 (1907). RECEIVED March 20, 1935. Presented before the Division of Industrial and Engineering Chemistry at the 89th Meeting of the American Chemical Society, New York, N . Y., April22 to 26,1936.
Dicarboxylic Acid Esters of Tetrahydrofurfuryl Alcohol J. N. BORGLIN Hercules Powder Company, Wilmington, Del.
AKETTI ( 3 ) previously described the preparation of the acetate, propionate, butyrate, valerate, benzoate, and furoate of this alcohol. Hewlett (1) prepared the chloroacetate, iodoacetate, oxalate, and salicylate. The oxalate is the only dicarboxylic acid ester reported. The following paragraphs will describe the preparation and properties of dicarboxylic acid esters of tetrahydrofurfuryl alcohol and phthalic anhydride and also terpinene maleic anhydride. The esters of other dicarboxylic acids, such as succinic, sebacic, maleic, etc., may be similarly prepared. The preparation of terpinene maleic anhydride has been described by Peterson and Littman (8).
Preparation FROM TERPINENE MALEICANHYDRIDE.Four hundred and fifty parts by weight of terpinene maleic anhydride and 95 parts by weight of tetrahydrofurfuryl alcohol, refined to remove furfuryl alcoho1,l were heated 36 hours a t 170' to 190' C. under a blanket of carbon dioxide. The excess alcohol was removed by reduced pressure distillation, whereby 711 parts or a n 89 per cent yield of a semi-solid ester resulted. This ester was equivalent to a WW grade of rosin in color and had a n acid number of 66.5. The half-ester has an acid number of 167. The acid ester obtained may be further esterified by means of an aliphatic alcohol. Thus, when 100 parts by weight of the ester were heated 16 hours a t 160' C. with 100 parts by weight of butyl alcohol and 10 parts by weight of toluene, and the volatile constituent was removed by reduced pressure distillation, 103 parts by weight of a pale-colored ester were recovered which analyzed as follows : Acid No. Refractive index
1 The furfuryl alaohol was removed b y treating the tetrahydrofurfuryl alcohol with sulfur dioxide, allowed t o stand several hours, filtered, and redistilled under reduced pressure. The furfuryl alcohol may also be removed by contacting with fuller's earth at elevated temperature and distillation under reduced pressure.
I n these experiments purified tetrahydrofurfuryl alcohol was used. If, however, the alcohol used contains furfuryl alcohol, the resulting esters are quite dark. Catalytic hydrogenation of the latter products results in esters of satisfactory color. FROM MALEICANHYDRIDE.Ninety-eight parts by weight of maleic anhydride and 200 parts by weight of tetrahydrofurfuryl alcohol were refluxed 48 hours at 170' t o 190' C. with 20 parts by weight of toluene to remove the water of reaction. This toluene was removed as needed. The excess alcohol and toluene were removed by reduced pressure distillation, whereby a pale-colored liquid ester was recovered and which analyzed as follows: Acid No. Refractive index (20' C.) Sp. gr. (15.6°/15.60 C.)
The half-ester of maleic anhydride has an acid number of 282. FROMPHTHALIC ANHYDRIDE.One hundred parts by weight of phthalic anhydride and 150 parts by weight of tetrahydrofurfuryl alcohol were heated 48 hours a t 170' to 190' C. with 20 parts by weight of toluene. The excess alcohol and toluene were removed by reduced pressure distillation. The resulting residue was a pale-colored liquid ester which analyzed as follows: Acid No. Refractive index ( Z O O C.) Sp. gr. (15.6°/15.60 C.)
64.5 1.6260 1.2165
The half-ester of phthalic anhydride has an acid number of 226. For the preparations described, the reactants were placed in a round-bottom flask to which was connected a 12-inch unpacked Liebig column; the latter was connected to a water condenser. This arrangement permitted the water of reaction to distill off,, leaving anhydrous reactants in the flask. If the water of reaction is not removed, the rate of esterification is appreciably reduced. These esters have rather high acid numbers which can be reduced by more extended heating or by the use of a higher temperature. Also, esters of lower acid number can be pre-
INDUSTRIAL AND ENGINEERING CHEMISTRY pared by first esterifying with tetrahydrofurfuryl alcohol or furfuryl alcohol and then completing the esterification by means of a more active alcohol such as butyl alcohol. This also results in esters of lower viscosity.
Properties These dicarboxylic acid esters of tetrahydrofurfuryl alcohol are pale in color when prepared in an inert atmosphere as carbon dioxide or nitrogen. They are thick, viscous liquids. Using an aliphatic alcohol such as butyl alcohol to complete the esterification results in products of decreased viscosity. Their boiling points are above 300" C., which, together with their ability to colloid nitrocotton in the presence of alcohol and their compatibility with nitrocellulose, classifies them as plasticizers for nitrocellulose. They are readily soluble in organic solvents such as alcohol, acetone, benzene, butyl alcohol, etc., and insoluble in water.
VOL. 28, NO. I
,4 number of lacquer formulations were made wherein tetrahydrofurfuryl terpinene maleate was compared with dibutyl phthalate: Materials
Nitrocellulose R.S. '/s-in. 8 8 Tetrahydrofurfuryl .. .. terpinene maleate ' Dibutyl phthalate 3.2 3.2 Dammar resin 6.4 Ester gum 6:4 8 8 . Ethyl acetate Butyl acetate 30 30 Toluene 44.4 44.4 Fence test, days 36 17 Diacoloration 2 4 .
30 44.4 42 4
8 8 i:6
6 8 6.4
30 30 30 30 44.4 44.4 44.4 44.4 46 63 42 32 3 3 3 . .
I n the absence of actual hardness data, tetrahydrofurfuryl terpinene maleate is a plasticizing resin, since i t is possible to replace all of the dammar resin and most of the plasticizer. Both durability and discoloration results are quite favorable.
Use with Cellulose Esters
Tetrahydrofurfuryl terpinene maleate dissolves cellulose acetobutyrate or acetate with the aid of heat to about a 20 per cent solution. This product is non-tacky a t room temperature, is thermoplastic, and is transparent in thin films.
(I) Hewlett, Iowa State Coll. J. Sci., 6, 439 (1932). (2) Peterson and Littman, U. S. P a t e n t 1,993,025 ( M a r c h 5 , 1935). 50, 1821 (1928). (3) Zanetti, J.Am. Chem. SOC., RECEIVED July 18, 1935.
Removal of Silica from Solution at Boiler Temperatures FREDERICK G. STRAUB Chemical Engineering Division, University of Illinois, Urbana, Ill.
S PART of a research on the prevention of silica scale in steam boilers, it became advisable to determine methods of removing silica from solution a t boiler temperatures. Small amounts of soluble siliha enter steam boilers through the feed water and slowly concentrate there until a concentration suitable for scale formation is reached. If it were possible to add chemicals to the boiler feed water which would react with the silica t o form an insoluble compound, the concentration of the silica might be kept low enough to prevent silica scale from forming.
The removal of silica from solution at boiler temperatures (182"to 282" C.) by the addition of calcium and magnesium and aluminum compounds was studied. The solubility of the resulting silicates was determined. When magnesium oxide is present in excess, the silica content of the water is less than 0.10 millimole per liter. When sodium aluminate is present with the magnesium, this solubility is less than 0.05 millimole per liter. High concentrations (45 millimoles per liter) of sodium hydroxide do not increase the solubility of the silica.
The tests conducted to study the removal of silica from solution were run in steel bombs previously described (1). The desired solutions and solids were placed in the larger steel bombs and held under pressure a t the desired temperature until equilibrium had been reached, and were then sampled by passing the solution through a filter into a smaller sealed bomb at a lower temperature. After sampling, the bombs were removed from the constant-temperature furnaces and, when cooled, the solutions were removed and analyzed. The solutions containing the soluble silicate were prepared by adding definite amounts of a standard sodium silicate solution, along with the other desired chemicals, to the solution in the lower bombs. The standard sodium silicate solution was prepared by diluting sodium silicate (specific gravity 1.41, 38 per 2.44 silica) with boiled distilled water. cent sodium oxide The composition of the solutions at the beginning and end of the tests were determined by analysis. The alkalinity was determined by titration, and the sulfate by precipitation as barium sulfate, as previously described (8). The silica was determined
by the colorimetric method when present in small amounts and gravimetrically by the perchloric acid method when present in larger amounts. The aluminate was precipitated, filtered, ignited, and weighed as alumina. Solutions of sodium hydroxide and sodium silicate were prepared with 3.76 millimoles per liter of silica and 15 to 50 millimoles per liter of sodium hydroxide. These were tested in the bombs at 243' C., and the silicate was in solution at the end, thus showing that it was still soluble a t this temperature. Similar tests were run with sodium aluminate also present in amounts between 0.5and 1.5 millimoles per liter, and the silica and aluminate were found to be soluble a t this temperature. Tests were then run with tricalcium phosphate present with the sodium hydroxide and silicate a t 182", 207O, 243O, and 282" C. The silica concentrated was not reduced and the phosphate content of the solutions was found to be between 0.15 and 0.20 millimole per liter at all the temperatures tested. When aluminate, silicate,