INDUSTRIAL AND ENGINEERING
June, 1934
cals used in the nonferrous mining industries. However, the company is endeavoring to balance its operations by wider diversification, one move of which is the building of the new $7,000,000 alkali plant a t Corpus Christi, Texas, jointly with the Pittsburgh Plate Glass Company. The prospects for the company are brighter, and the stock has considerable speculative merit. Because of their generally wide diversification of products and activities, most of these miscellaneous chemicals may be called the "investment trusts" of the chemical group. These units will benefit from any or all improvements which take place along the business front. As conditions move toward normal, the net earnings of these companies are expected to improve sharply. They have all the advantages of being in a young, growing industry and are not afraid to spend money for research. Who today can predict what may come out of our laboratories as a new development which may create a mofitable new branch of business? As a matter of fact, investors' by their attitude toward these stocks' are expecting like this to happen* It Offers a to men who are operating in the laboratories.
CHEMISTRY
611
CONCLUSIONS An analysis of the principal factors affecting chemical securities shows that they answer the requirements exceptionally well for the ideal investment, that this fact has become commonly recognized by investors, and they have correspondingly bid the more attractive issues up to high levels. h'evertheless, we are distinctly bullish on good chemical securities for the following three reasons: (1) The chemical industry is the industry which should profit most from new inventions and discoveries. It is where the electrical industry was about twenty years ago. (2) Chemical securities should be one of the groups to benefit most from inflation, when, as, and if it comes. This would be true because of the industry's large holdings of natural resources. (3) The market for chemical securities is in the right sector of the business cycle to profit from the inevitable improvement in business as a whole. RECEIVED April 3, 1934. Presented before the General Meeting at the 87th Meeting of the American Chemical Society, St. Petersburg, Fls., March 25 t o 30, 1934.
Formamide P. L. MAGILL The R. & H. Chemicals Department, E. I . du Pont de Nemours & Company, Inc., Niagara Falls, N. Y. Formamide is a new chemical to industry. Itsfreezing point is near that of water, its specific
ORMAMIDE in the past has not been available to
of metals. Some binary salts as s o l u t e s have a h i g h e r COefficient of ionization in form-
a p r o c e s s has been developed which m a k e s i t a v a i l a b l e and its dielectric conslant is higher than that of acids, such as tribromoacetic, i n commercial quantities. water. It has unique solubility characteristics. are little ionized in formamide It is adaptable to novel syntheses and may be (23). S a l t s which f o r m hyHere are described some of the used as a solvent in electrolytic deposition. drates form solvates with formP r o p e r t i e s and reactions disc o v e r e d i n c i d e n t a1 t o this amide ( 5 ) . work. Formamide was early TABLEI. PHYSICAL PROPERTIES OF FORMAMIDE prepared by the dehydration of ammonium formate (7) and later by the direct synthesis from carbon monoxide and am- &felting point, C. 2 . 5 5 (19) 210 decompn. (16) monia ( I O , 16). It was known to condense with formalde- E:YG$rPZis,"azi ( E ) , CGS units 84 (24) 1.44900 (16) hyde in the presence of potassium carbonate to give n-hy- ~ ~ , f ~ ~ $ ' ~ t i ~ , "joules,gram/O ."xc,, c, 2.306 ( 2 5 ) 134,900 (13) droxymethylformamide, HCONHCH20H, and in the pres- Heat of combustion (liquid), gram. caI./gram mol. 38.47 (2) ence of acid condensing agents to give methylenebisform- Heat Of fusion' gram pressure: amide, CH2(KHCOH)2(9). With tannin and formaldehyde M m . Hg C. Mm. H g ' C. Mn. H a i t reacts to give methylenetanninformamide, CH2NH129.4 29.7 166.4 170.6 188.4 355.9 70.4 174.9 231.2 192.4 406.1 COHCI4H90~(22). The equilibrium constant ( K ) of CO iii:; 103.4 179.3 265.9 210.7" 760.0(10) NH, HCONH, a t several temperatures was found to be 160.5 138.7 as follows: Density: c. dro c. dyo - PCOPNHI Ts~p, K 'coPsHs TEMP. 18 1.13510 * 2 X 10-5 (19) 35 1.12068 2 t 2 X 10-5 P H C ON H ~ PHCONH:
+
-
C. 127 177
Abs. 400
450
O
20 321
C. 200 227
Abs. 473 500
960 3130 (14)
PHYSICAL PROPERTIES Pure formamide is a colorless, odorless, hygroscopic liquid. The commercial product may have a slight odor and a somewhat sour taste. I n appearance and feel it resembles glycerol although it has a lower viscosity. Other properties are given in Table I. Formamide is not unlike water in some respects. The unusually high dielectric constant has made it of interest as an ionizing solvent and as a medium for the electrodeposition
20 1.1339 =k 1 X 10-6 25 1.12918 i 1 X 10-5 Surface tension (air):
c.
Dynes/cm.
18 20 25 Viscosity:
58.53 (19) 58.35 57.91
c.
50
1.1078
a
c.
35 50
2 X 10-4
Dynes/cm.
67.11 55.72
Cgs. units
18 0.03970 (19) 0.03764 20 25 0.03302 5 Extrapolated boiling point.
I n a study of the electrodeposition of metals from formamide it was possible to deposit the respective cations from
INDUSTRIAL AND ENGINEERING
612
formamide solutions of copper sulfate, copper chloride, lead chloride, zinc chloride, zinc oxide, and tin chloride, while no deposits were obtained from chloride solutions of nickel, cobalt, iron, aluminum, and magnesium (17). Deposits of alloys of aluminum with iron and with zinc were obtained although pure aluminum could not be deposited (1). Because of its solvent action (Table 11) formamide has been found useful in the determination of absorption spectra and optical rotation. Its convenient freezing point has made it useful in the determination of molecular weights. TABLE11. FORMAMIDE AS A SOLVENP COMPONENT SOLUBILITY Insoluble Albumin Dissolves A1bum ose s Miscible in all proportions Alcohol Very soluble Alkali metal acetates Alkali metal carbonatea Practical1 insoluble Very so&e Ammonium acetate Practically insoluble Ammonium chloride Miscible in all proportions st tamp. above 115" C. Ammonium formate Very insoluble, Ammonium sulfate Complete1 miscible Aniline Slight1 aoyuble Benzene I n s o d e Benzene chloroInsoluble Benzene' nitroDissolves and gelatinizes Cellulos; acetate Slightly soluble Chloroform Moderately soluble Copper acetate Slightly soluble Copper carbonatea Moderately soluble Copper chloride8 Moderately soluble Copper sulfate Completely miscible Dimethyl sulfate Sljghtly aoluble: forms a miscible, dense liquid Ether Dissolves at 100-150° C. Formaldehyde polymer Dissolves &Fructose Immiscible Gasoline Equimolar proportion forms clear soln. on heating Glucose Hydrocarbons, aromatic Insoluble Soluble Insulin Dissolves AlDha-lactose Dissolves Peptone Insoluble in hot formamide Petroleum oil Completely mjscjble Phenol Completely miscible Propionic acid TXnnolven ..-.. Starch Completely miscible WSkU Moderately soluble Zinc acetates Moderately soluble Zinc formate Moderately soluble Zinc sulfate a Data compiled from miscellaneous sourcea.
__
REACTIONS Formamide may be thermally decomposed according to the following two main reactions:
Boiling formamide, a t atmospheric pressure. decomposes at the rate of about 0.5 per cent per minuta (16). In the liquid phase and in the absence of a catalyst, reaction 2 predominates. Formamide can be vaporized with little decomposition (less than 1 per cent) provided the liquid formamide is contacted in a finely divided condition with surfaces heated to a temperature between 200" and 370" C. and accumulation of liquid formamide is avoided (S,11 , 16). I n the presence of suitable catalysts such as coke, thoria, and pumice, reaction 1 may be favored at a temperature between 400" and 600" C . to produce hydrocyanic acid yields in excess of 90 per cent (6, 8, 12, 16, 16). I n the catalytic dehydration of formamide there is a critical temperature around 650" to 700" C. where a secondary reaction sets in which causes rapid rise in temperature and a very low yield of hydrocyanic acid, probably because of the hydrolysis of the hydrocyanic acid already formed. Formamide forms numerous addition compounds and substitution products with inorganic salts, for example: SbCls 3HCONHz +Sb(HC0NH)s 3HC1 C@O, + 4HCONHz +CU(HCONH)~.~HCONH~ + H2SOd PbClz + HCONHZ +PbCIz.HCONH2
+
+
I n the cold, water very slowly hydrolyzes formamide to ammonium formate. Acids or alkalies increase the rate of
CHEMISTRY
Vol. 26, No. 6
hydrolysis. A water solution of formamide will react with chlorine to form the explosive compound HCONCI,, according to the equation: HCONHz
+ 2C11-
2HC1
+ HCONCIZ
I n the presence of an inert solvent, sodium will react with formamide according to the following equation: Na
+ HCONH,
--f
HCONHNa
+ l/*H1
Formamide acid sulfate possesses an unusually high degree of reactivity. It will readily react with alcohols to form the corresponding formic ester according to the following equation : ROH HCONH,HzSO4 +HCOOR NH4HSO4
+
+
In this manner the formic ester of allyl alcohol can be made with yields of 98 per cent without undergoing any of the usual changes encountered in other methods of esterification (16, 20). Ethylene glycol monoformate, which in contact with wakr readily undergoes hydrolysis, may be made in anhydrous medium using formamide acid sulfate. It might be said that the formamide acid sulfate bears a similar relation in reactivity to formic acid that acetic anhydride does to acetic acid. The amide acid sulfate should react with any compound capable of giving up its hydrogen, for example: PhNHn HCONHzHsS04 + PhNHCHO NHJ€SOd
+
+
(16,21)
This reaction, as well as similar reactions with many of the aliphatic amines, has been shown to take place. I n general, this reaction does not take place with those aliphatic amines which are more basic than ammonia. When formamide is heated with sulfur and a monoaryl amine which may have hydrocarbon substituents in the benzene nucleus, there is obtained a good yield of the mercaptothiazole derivative (16). For example, a mixture of one mole of aniline, 1.6 moles of formamide, and 2.66 moles of sulfur was heated in a bomb for 4 hours a t 195" C. The crude mercaptobenzothiazole was extracted with acid and the thiazole dissolved out with alkali and precipitated with acid, giving 103.8 grams of the purified product, melting a t 178" C. The yield based on aniline used was 63.6 per cent. The same procedure was carried out with a number of other aryl amines-e. g., p-toluidine gave an 84 per cent yield of the corresponding methyl mercaptobenzothiazole while pnaphthylamine gave 73.7 per cent of mercapto-p-naphthothiazole. Many of the mercaptothia- ole derivatives are excellent rubber accelerators. p-Phenylenediamine, p-aminophenol, and o-aminophenol were heated in a bomb a t 195' C. with formamide and sulfur for 4 hours and the products worked up in the same manner as employed in the case of aniline (16). I n the case of the diamine, twice the usual amount of formamide and sulfur was employed. All the products were dark-colored amorphous powders, insoluble in water and the usual organic solvents. They dissolved in solutions of sodium hydroxide to give brilliantly colored solutions and were reprecipitated by the action of acids. The p-phenylenediamine product gave a green solution in alkaline solution, the paminophenol product a blue-green solution, and the o-aminophenol product gave a brown solution. These alkaline solutions did not give precipitates with iodine as is the case with mercaptobenzothiazoles. The following is suggested as a possible mechanism for the reaction by which mercaptobenzothiazole is obtained when aniline, formamide, and sulfur are heated under pressure. The first step is the formation of formanilide and ammonia by the action of formamide on aniline:
I N D U S T R I A L A N D E N G I N E E R I N G C H E M I ST R Y
June, 1934 CeHsNHp
+
NH*.CHO
CBH5NH.CHO
+
SHs
Experiments have shown that this takes place a t once when the compounds in question are heated gently. The second step is probably the formation of the o-thiophenol of formanilide by the action of hot sulfur on formanilide. This hypothesis is based on the findings of Sebrell and Boord for the mechanism of the formation of mercaptobenzothiazole by the action of sulfur and thiocarbanilide (18):
The third step by which mercaptobenzothiazole is formed may then take place as follows: H
N
+S + f\'%-SH
+H20
PREPARATION Formamide has been prepared by a great many methods, but only those capable of being readily adapted to laboratory procedure giving relatively high yields are worth mentioning. PARTIALHYDROLYSIS OF HYDROGEN CYANIDE. The earliest approach to the preparation of amides from the nitriles was made when the double compound of formamide and hydrogen chloride was obtained (4). This compound can easily be obtained in the following manner which is a modification of the original method (16): About 300 cc. of dry ether are cooled to -5" C., and into this is passed dry hydrochloric acid gas until approximately 0.5 mole has been taken up. To this is then added 0.5 mole of water. The resultant solution is cooled to -15" to -20" C. One-half mole of hydrogen cyanide is then dropped in while stirring, and the reaction mixture is allowed to'stand. The reaction occurs more rapidly at higher temperatures, but, as the reaction is energetic and liberates heat, it is advisable t o keep the mixture cool. The ether absorbs the reaction heat and helps to keep the reaction from becoming too violent. The reaction product, formamide hydrochloride, is insoluble in ether and can be filtered off; it is white and crystallizes in needles. It is very unstable and, upon warming to f15" C., decomposes explosively into carbon monoxide and ammonium chloride according to the equation : HCONHZ.HC1-
NH&l
+ CO
For this reason its use is limited, as there are few reactions that can be handled with so unstable a compound. The same general characteristics hold for the other halogen acid compounds of formamide. It is difficult to obtain free formamide from this halogen complex. If an attempt is made t o neutralize the halogen acid by means of an alkali, as HCONH,.HCl -I-NaOH
--f
HCONHz + NaCl
+ H1O
part of the compound is converted to formic acid by the water formed by the above reaction while a considerable portion decomposes into ammonium chloride and carbon monoxide as a result of the heat generated when partial neutralization takes place. A somewhat more satisfactory method is to carry out the neutralization method with a slow stream of dry ammonia. The same scheme to complete a partial
613
hydrolysis of hydrocyanic acid is applicable to sulfuric acid, since a definite hydrate is formed with water, HzSOI.HIO. The following method has been used with good success in these laboratories for preparing small quantities of formamide : One mole sulfuric acid monohydrate weighing approximately 116.1 grams is cooled to about 0" C., and into this is poured while stirring 1 mole of hydrogen cyanide which likewise has been cooled. The reactants are kept cool to prevent rapid reaction and loss of hydrogen cyanide through evaporation, since the ingredients become warm upon mixing. The resultant product is a clear, colorless liquid. The reactants contained in a 250-cc. flask are kept in a refrigerator at 10" C. After about 2 days, a marked increase in viscosity is noticed, and after the fifth day the contents of the flask may have a consistency of a heavy sirup. Soon after this, white crystals begin to form and after another day the entire reactants become a solid white crystalline mass of formamide acid sulfate, HCONH*.H&304. This compound is hygroscopic, is stable through a wide range of temperatures, and may be warmed to about 60" C. without noticeable decomposition. At higher temperatures the compound decomposes into carbon monoxide and ammonium acid sulfate. To recover formamide from formamide acid sulfate, 1 mole of the latter is placed in a heavy 500-cc. flask and covered with 250 cc. of absolute ether. The crystalline mass is broken up with a glass rod, and a slow stream of ammonia is bubbled through the mixture while it is stirred standing in ice water. As the formamide acid sulfate becomes neutralized, the crystalline component becomes sticky and finally fluid, owing to the liberation of formamide which is only slightly soluble in ether. The neutralization by ammonia is continued until the reaction is complete as shown by the equation: HCONH;.HsSOd
+ NHJ +HCONHn + NHiHSOi
The ether is distilled off and absolute alcohol is added to the residue. A little ammonia is bubbled through the alcohol solution to insure neutralization and the ammonium sulfate is separated by filtration. Formamide weighing about 42 grams may be recovered by vacuum distillation. The yield is about 93 per cent. The time required for the mobile reaction mixture of sulfuric acid monohydrate and hydrogen cyanide to be changed first to a viscous colorless liquid and thence into a white crystalline mass, may be greatly shortened by the introduction of halogen ions which act as catalysts. The reaction rate may be increased to such an extent that it takes place with explosive violence if sufficient catalyst is used. The effect of different halogen compounds is shown in Table 111. TABLE 111. EFFECTOF HALOGEN COMPOUNDS AMOUNT OF CATALYST TIMEF O R EQUALS 0.0000282 MOLEOF HALIDEION COMPLETE PEBMOLEHCN OBSERVATIONS REACTION Gram Days HF generated did not dissolve in the re0.012 NaF 6.5 action mixture as readily an did the other halogen acids: change in vis. cosity was slow 0.015 NH&l Change in viscosity wan noted after 5 second day, but reaction waa slow 0.028 NH4Br Reaction progressed rapidly. stirring 20 hr. and additional cooling with' ice w+er were required to prevent overheating 0.040 NHiI Hlproduced b reaction of, "$1 with 7 :SO4 waa d)ecornposed into iodme; no catalyst action WBB obtained
PURIFICATION OF FORMAMIDE Formamide can best be purified by high-vacuum distillation, followed by low-temperature crystallization out of contact with moist air (19). It is only with difficulty that a mixture of methanol and formamide can be completely separated. Methanol and formamide react according to the equation:
INDUSTRIAL AND ENGINEERING CHEMISTRY
614 CHaOH
+ HCONHs e NHI + HCOOCHt
Both ammonia and methyl formate have higher vapor pressures than either methanol or formamide with the result that, when a distillation of this mixture is attempted, the ammonia and methyl formate pass over with the methanol in considerable quantities in the vapor state and upon condensation recombine with liberation of heat to reform formamide in the distillate.
EFFECT OF FORMAMIDE UPON CONSTRUCTION MATERIALS Neither oak, cypress, nor redwood unprotected is suitable t o have in contact with the formamide, owing to discoloration produced in the formamide. Varnish, Duco paint, Bakelite, shellac, red lead paint, and white lead paint are not satisfactory coatings for wood to be used in contact with formamide. Allegheny metal subjected to formamide lost approximately 10 times the weight per square inch that aluminum, treated in the same manner, did. Anhydrous and aqueous formamide in contact with air cause a rapid corrosion of brass. Iron rapidly corrodes in the presence of formamide and discolors formamide in contact with it. Lead is relatively little corroded, but the formamide in contact with lead becomes discolored. Aluminum and glass seem to be the most satisfactory materials for storage of the amide. A quantity of several tons of formamide has been in storage over 2 years in glass carboys without any noticeable change in color or melting point. Tests over a shorter period indicate that aluminum is as satisfactory as glass.
Vol. 26, No. 6
LITERATURE CITED (1) Blue and Mathers, Trans. Am. EZectrochem. SOC.,Preprint, 1933. (2) Bruni and Trovanelli, Gazz. china. ital., 34b, 350 (1904); LandoltBBrnstein, Physikalisch-Chemische Tabellen, 5th ed., Vol. 11, p. 1429, Julius Springer, Berlin, 1923. (3) Carlisle, U. S. Patent 1,934,485 (Nov. 7, 1933). (4) Claisen and Matthews, Ber., 16, 311 (1883). (5) Davis, Putnam, and Jones, J . Franklin Inst., 180, 567-601 (1915). (6) Ewan, U.
S.Patent 1,876,213 (Sept. 6, 1933). (7) Fick, U. S. Patent 1,582,675 (April 27, 1906). (8) Jaeger, U. S.Patent 1,920,795 (Aug. 1, 1933). (9) Kalle & Co., Akt.-Ges., German Patents 164,610, 164,611 (1902); J . SOC.Chem. Ind., 25, 283 (1906). (10) Lacy, U. S.Patent 1,787,483 (Jan. 6, 19311. (11) Ibid., 1,934,433 (Nov. 7, 1933). (12) Magill and Carlisle, U. S. Patent 1,675,366 (July 3, 1928). (13) Meyer and Orthner, Ber., 54, 1705-9 (1921). (14) Ibid., 5 5 , 857 (1922). (15) Michael, U. S.Patent 1,846,221 (Feb. 23, 1932). (16) Roessler & Hasslacher Chem. Co. and E. I. du Pont de Nemours & Co., unpublished work.
(17) Rohler, 2. Elektrochem., 16, 419 (1910). (18) Sebrell and Boord, J . Am. Chem. SOC.,45, 2390 (1923); Sebrell and Bedford, U. S. Patent 1,591,440 (July 6, 1926). (19) Smith, G. F., J. Chem. SOC.,1931, 3257-63. (20) Trusler, U. S.Patent 1,584,907 (May 18, 1926). (21) Ibid., 1,656,252 (Jan. 17, 1928). (22) Voswinkel, A., German Patent 165,980 (Xov. 27, 1905) ; Chem. Zentr., 1906, I, 512. (23) Walden, Nature, 1912, 387; Bull. St. Petersburg Acad. Sci., 1911,1055-82; Chem. Zentr., 1912, I, 122-3. (24) Walden, 2. physik. Chem., 46, 103-88 (1903); Chem. Zentr., 1904, I, 574. (25) Walden, Ibid., 58, 479 (1907). International Critical Tables, Vol. V, p. 107, McGraw-Hill, New York, 1926.
RECEIPBD November 9, 1933.
Utilization of Sulfite Liquor GUY C. HOWARD, Wausau, Wis.
I n so far as is permissible at this time, work is tion in oxygen demand as comHE m a i n process f o r reported which has been conducted during recent pared with the untreated liquors. treating sulfite liquor is The improved character of the a precipitation treatment of the liquors with a c a u s t i c years at the Paper Company, effluent as regards stream pollulime reagent which is carried Rothschizd* On the Howard system O f tion results: (1) from the retreating su&te liquor. moval of the lignin constituent out in a manner to yield three which is the major cause of the primary products; (1) a calcium The work divides into a consideration of main oxygen demand and the probable sulfite product for use in makan$ supplemental processes of treatment. The source of whatever toxic effects ing fresh cooking (2) an main process is designed to afford an economical these liquors may have on fish organic product in solid form means of treating these liquors to avoid the oba n d fish f o o d s , (2) from the constituting the lignin compojections raised to their discharge into streams alterations in the carbohydrate nent of the liquor for use as a constituents taking place under boiler fuel, and (3) a process effluand to recover products for we at the pulp mill the alkaline treatment of the ent containing the carbohydrate in making fresh cooking acid and as a boiler fuel. process, (3) from the treatment constituents of the liquor in The supplemental processes are f o r making spehaving satisfied the lime dealtered f o r m s a n d h a v i n g a cial products* mand of the raw l i q u o r , and greatly improved character as (4) from the effluent being regards stream pollution. A detailed description of this fractional precipitation has already alkaline rather than acid. If desired, the main process effluent can be given a supplebeen pub1ished.l The process does not involve evaporation of the liquors mental heat treatment by which some additional organic and is designed to handle both the strong and dilute liquor matter can be precipitated and removed, thereby yielding a drainage from the blow pits. Standard equipment is used further improved effluent, but ordinarily this additional treatthroughout the process and consists of raw-liquor storage ment is not considered necessary. A number of supplemental processes have been developed tanks, reaction tanks, settling tanks, rotary vacuum filter, for making special products, but the markets for such products pumps, piping, and the necessary auxiliary equipment. This main process results in the removal of about 50 per are not unlimited and for the present, at least, the main proccent of the organic matter contained in the liquors, and the ess only should be considered as available to the pulp indusprocess effluent will normally show around 85 per cent reduc- try as a means of avoiding objections to discharging these liquors into streams and on the basis of the pulp mill’s utiliz1 Howard, G.C., IND.Exa. CSEM.,22,11844 (1930).
T
