INDUSTRIAL A N D ENGINEERING CHEMISTRY
68
dicalcium phosphate contained about 5.5 per cent moisture and no free acid or monocalcium phosphate. Mixtures of calcium cyanamide with the two phosphates were prepared in the proportions of 50 parts of the former to 1000 parts of the latter and stored in bags in the storehouse for 32 weeks. The rate of calcium cyanamide decomposition was found to be very much slower in both cases than in mixture with acid phosphate, the rate in the mixture containing dicalcium phosphate being nearly as slow as for calcium cyanamide alone. Urea, dicyanodiamide, and guanylurea were the identified transformation products in the mixture containing monocalcium phosphate, and the results showed conclusively that this phosphate is capable of causing the hydrolysis of dicyanodiamide to guanylurea. Urea and dicyanodiamide were formed in the mixture containing dicalcium phosphate. Guanylurea was not present in a detectable amount. , Stability of Dicyanodiamide and Urea in Mixture with Acid Phosphate
To determine the stability of the two principal decomposition products of calcium cyanamide-namely, dicyanodiamide and urea-in mixture with acid phosphate, three mixtures (2.27 kg. each) of C. P. dicyanodiamide and acid phosphate were prepared and stored in cloth bags. Before mixing with the dicyanodiamide, sufficient calcium oxide was added to the acid phosphate used in Mixture N to approximate the acid conditions existing in mixtures containing 50 parts of calcium cyanamide per 1000 parts of acid phosphate.
-
Vol. 17, N o . 1
HzCNz f HZO-CO(NHZ)~
(4)
I n large quantities of such mixtures, where a relatively high temperature persists for some time, considerable ammonia may be formed by hydrolysis of the urea. CO(NH2)z
+ Hz0-2”~
+ COz
(6)
When calcium cyanamide is mixed with acid phosphate containing what may be termed a normal amount of free acid, in the ratio of 1 to 10, or with air-dried acid phosphate in the ratio of 1to 20, the mixtures usually contain no free acid and comparatively little monocalcium phosphate, and hence the free cyanamide formed is largely polymerized to dicyanodiamide. 2HzCNz-
(HzCNdz
(6)
The dicyanodiamide formed in the mixtures is hydrolyzed to guanylurea, slowly at atmospheric temperatures and rapidly a t elevated temperatures such as might exist for some time when large quantities of the mixtures are prepared. (HzCNz)z
+ HzO+NHzC(NH)NHCONHz
(7)
Some unidentified nitrogen compound or compounds are evidently formed also in calcium cyanamide-acid phosphate mixtures. Acknowledgment
The authors are indebted to E. J. Fox, L. A. Pinck, M. A. Kelly, K. S. Love, M. S. Sherman, J. H. McCormick, W. Rosett, and L. Smith for the analytical data presented in this paper. Bibliography
1-Soderbaum, K g l . Landtbruks-Akad. Handl. T i d . , 46, 201 (1907). 2-Immendorf and Kempski, Centr. Bakt. Parasitenk. I I Abt., 20, TABLEVI-STABILITY OP DICYANODIAMIDE IN MIXTURE WITH ACID PHOSPHATE 304 (1908). PER CENT PRESENT PER CEXT ORIGINAl, 3-Anon., L’Engrais, 28, 159 (1908). IMMEDIATELY AFTER MIXING DICYANODIAMIDE 4-Anon., A m . Fertilizer, 29, No. 5 , 18 (1908). Period of Hydrolyzed Dicyano5-Namba and Kanomata, Bull. Coll. Agr. I m p . Univ. Tokyo, 7, 631 Free storage to diamide Present guanylurea PzOs Weeks nitrogen Mixture (1908); J . Chem. SOC.(London), 94, 623 (1908). 32.6 49 66.5 6-Hall, J . Board Agr., 14, 652 (1908). 0.46 0 006 N 58.2 27.3 32 1.45 NA 1 10 7-Pluvinage, Bull. SOC. encour. i n d . nut., 111, 549 (1909). 28.0 32 73.5 1.94 1.45 NB 8-Masson-Polet, J . soc. agy. Brabant el Hainaut, 64, 626 (1909). 9-Frear, Pa. Dept. Agr., Bull. 177, 78 (1909). It is seen that in mixture with acid phosphate, dicyanodi10-Schneidewind and Myer, Landw. Jahrb., 89, Erg 3, 236 (1910). 11-KBnig, Deut. Landw. Presse, 57, 375 (1910). amide is converted pirncipally into guanylurea. No change 12-Ampola, A n n . r . slaz. chim. agrar. sper. Roma, [2] 4, 73 (1910). could be detected in the urea content of mixtures containing 13-Hendrick, J . Soc. Chem. I n d . , SO, 522 (1911). urea and acid phosphate stored in cloth bags for 6 months. 14-Mil0, Arch. Suzkerind., a0, 1039 (1912). lt5-Christensen, Ugeskr. Landm., 58, 51 (1913). Discussion of Chemical Reaction Involved 16-De Wildt and Berkhout, Arch. Suikerind., 21, 717 (1913). 17--Brackett, J. I n d . Eng. Chem., 6, 933 (1913). The reactions occurring in mixtures of calcium cyanamide 18-Koppen, Illus. Landw. Z l g . , 54, 181(1914). 19-Pranke, American Pertiher Handbook, 1914, p. 67. and acid phosphate may be summarized as follows: 20-Hill and Landis, J . I n d . Eng. Chem., 6 , 20 (1914). Calcium cyanamide reacts with any moisture present in 21-Abr, Mztt. deut. Landw.-ges., S O , 732 (1915). acid phosphate to give free cyanamide and calcium hydroxide, 22-Malpeaux, V i e agr. el rurale, 6, 28 (1915). calcium acid cyanamide being formed as an intermediate 23--Hals, Tids. Novske Landbr., 2 2 , 332 (1915). 24--Pranke, Commercial Fertzlizer, 10, No. 2, 15 (1915). product. 25--King, Ibrd , 10, No. 1, 14 (1915). 2CaCNz 2Hz0-+Ca(HCNz)z f Ca(0H)z (1) 26-Haselhoff, Fdhling’s Landw. Ztg., 66, 105 (1917). Ca(HCN& 2H20c;LLH?CNz Ca(OH)p (2) 27-Pranke, Chem. Met. Eng., 23, 1102 (1920), Calcium cyanamide reacts with monocalcium phosphate to 28--Harger, J . I n d . Ens. Chem., 12, 1111 (1920). 29-I,andis, A m . Feutzlizer, 64, No. 2, 49 (1921); J . I n d . Eng. Chem., 14, produce free cyanamide, dicalcium phosphate, and some tricalcium phosphate if the calcium cyanamide is present in 143 (1922). 3O--Breckenridge, Ibid., 14, 145 (1922). sufficient quantity. Calcium acid Cyanamide is formed as an 31-Aston, New Zealand Dept. A g r . , Annual Report 17, 187 (1909). intermediate product. 32-Assoc. Official Agr. Chem., Methods, 1920. p. 7. 33--Pranke, “Cyanamide,” 1915, p. 20. The Chemical Publishing Co., CaCNz Ca(HZPO&AHzCN2 2CaHPOd (3) Esston, Pa. The reaction with free phosphoric acid, and possibly with 34-The details and applications of this method will be published later. dicalcium phosphate, takes place in a similar manner. Mono3 6 F o x and Geldard, I n d . Eng Chem., 16, 743 (1923). 3&Matthews, J. Agr. Sci., 10, Part I, 72 (1920). calcium phosphate and free phosphoric acid also react with 37-Assoc. Official Agr. Chem., Methods, lSa0, p. 3.
++
+
+
+
the calcium hydroxide present in calcium cyanamide liberating water, which may be partially used up in Reactions 4; 5, and 7. I n mixtures containing considerable free acid or monocalcium phosphate, the free cyanamide produced principally by Reactions 2 and 3 is largely hydrolyzed within a short time to urea.
Production of Cyanamide in France-Cyanamide was produced in France in 1923 by three plants at Bellegrade, Marignac, and Brignoud. During the present year other cyanamide factories have been established, and it is anticipated that the total output of the French cyanamide factories in 1924 will reach 90,000 tons, representing 18,000 tons of nitrogen.
