US2433394A - Dicyandiamide sulfonates - Google Patents

Description

Patented Dec. 30, 1947 DICYANDIAMIDE SULFONATES Joseph H. Paden and Alexander F. MacLean, Stamford, Conn., assignors to American Cyanam d Company, New York, N. Y., a corporation of Maine No Drawing. Application October 25, 1945,

Serial No. 624,581

9 Claims.

This invention relates to the sulfonic acid salts of dicyandiamide and to methods of preparing the same.

It has been recorded in the literature that dicyandiamide, a neutral compound having a low ionization constant would not form salts with acids in aqueous solutions. In spite of this argument which refutes the formation of such salts, it has now been discovered that sulfonated salts of dicyandiamide can be prepared.

The sulfonate salts are prepared by reacting dicyandiamide with a sulfonic acid in a solvent for either or both of the reactants. Suitable solvents are ethers, esters, ketones, acids and the like. The following examples will serve to illustrate the preparation of sulfonate salts of dicyandiamide:

EXAMPLE 1 Dicyandzamide p-toluenesulfonate Reagents Molar Ratio Dicyanrliamide l. p-Toluenesulfonic acid 1.23 Acetic acid, glacial 4. 36

The dicyandiamide is added slowly to the mechanically stirred acetic acid solution of the ptoluenesulfonic acid at 25 C. The product begins to crystallize from solution before the addition of the dicyandiamide is completed. After completion of the addition of the dicyandiamide, the reaction mixture is then cooled to C. The colorless crystals are filtered, washed with methyl ethyl ketone containing a small amount of ptoluene sulfonic acid and dried under vacuum at 50 C. By means of potentiometric titration, the molecular weight was found to agree closely with the theoretical value of 256.

Dicyandiamide p-toluenesulfonate does not have a sharp melting or decomposition point, and since analytical data checks the theoretical com position, the optical and crystallographic properties are herein presented to characterize the ptoluenesulfonate. Dicyandiamide p-toluenesulfonate is a white, columnar solid with curved faces and a negative optic sign. In white light the refractive indices are as follows: e=1.54'7; p=1.582; and y=1.598. The apparent optic axial angles as observed in air are estimated to be greater than 100, and the true optic axial angle estimated therefrom is greater than 54. The principal vibration direction of on is at an angle of 30i1' to the elongation of the crystal.

EXAMPLE 2 Dicyandiamide benzy ls ulfonate Reagents 'MolarRatio Dicyandiamide. 1.00 Benzylsulfonic acid l. 16 Acetic acid, glacial 4; 00

Small portions of the benzylsulfonic acid are added to an agitated mixture of dicyandiamide and acetic acid at a temperature of substantially 40 C. The reaction mixture is stirred about one hour after the last portion of benzylsulfonic acid is added and the temperature is lowered to substantially 20 C. The solid dicyandiamide ben-, zylsulfonate is filtered, washed with methyl ethyl ketone containing 5% benzylsulfonic acid and dried under vacuum at about C. I

Dicyandiamide benzylsulfonate melts at 138 C., then resolidifies. The optical and crystallo r phic properties are herein presented to char-l acterize this salt. Dicyandimide benzylsulfonate is a white, lamellar solid with broken edges and positive optic sign. In white light the refractive indices are as follows: oz=1.4=; and 18:1.590. The apparent optic axial angle as observed in air is estimated to be greater than and the true optic axial angle estimated therefrom is greater than 60. The optic axial plane or principal optic section is perpendicular to the crystal face presented.

EXAMPLE 3 Dicyandiamide ethylsulfonate Reagents Molar Ratio Dicyandiamide l l. 00 Ethylsulfonic acid. 2. 56 Acetic acid, glacial, 31.80

55 fi=1.551; and 'y=1.569. The apparent optic axial angle as observed in air is 90 and the true optic axial angle is 54. The optic axial plane or principal optic section is perpendicular to the plane (010). The principal vibration directions are such that p is at an angle of 3i30', to 0" and 'y is parallel to fb. It"istoibe understoo'd that b= an"d' "C are the crystallographic axes.

The sulfonates described in the above e};- amples are typical of those that may be prepared by the present invention. p A

The sulfonate salts of dicyandiaxriide are useful as chemical. intermediatesimthe{preparation of fiameproofing compositions, chemotherapeutic agents, insecticides, synthetic "resins and for other purposes.

While the invention has been described' wi-th particular reference to specific embodimentsitPis to be understood that it is not to belimited thereto, but is to be construed broadly "andn' striated solely by the scope of the appended claims.

What is-claimedg;

1. sulfonic acid salt's of d jCYan'dia Iiide.

2. Dicyandiamide p-toluenesulfonate.

'Dicyandiarnide benzylsulfonate.

'4. Dicyandiamide ethylsulfonate.

. 5. A method Otpreparing SUlfQl'i3-tQSQ1tSjOfHi- "cyandiamide which includesthe steps of-reacting *dicyandiamidewitha-sulfonic acidin' a solvent for ithejicyandiamide :and asnlfionic :acid abelow .sub- :stantially;50 C. V

. a6. .Azmethod- :ofzpreparing sulforratetsaltsz Of diacyandiamide-sWhichzincludesitherstepsrof rwcting sin-. acetic aciddioyandiamide zandz'a sultonic; acid =qbelow-s substantiallyr50 =.C.,zand mecovering ;the diecyandiamidessuifonateztherefrom.

. 27.}A1methdd 16f .gureparing zdicyanfiiarnide pitoulenesulfonatemhi-ch includes -the:stepsof revact-,ing in acetic aididicyandiamide"with p tol uenesulfonic acid --b low subs'tanti-ally I50 -'C., "and recovering the dicyandiamide p-toluenesulfonate therefrom.

8. A method of preparing dicyandiamide benzylsulfonate which includes the steps of reacting in acetic acid dicyandiamide with be'nzylsulfonic :acid below substantially 50 C., and recovering "the dicyandiamide benzylsulfonate.

9. A method of preparing dicyandiamide ethylssulfonate which includes the steps of reacting in acetic acid dicyandiamide with ethylsulfonic sa-cidnbelowsubstantially 50 C., and recovering :the dicyandiamide ethylsulfonate therefrom.

JOSEPH H. PADEN. 5 ALEXANDER F. MACLEAN.

REFERENCES CITED vTheiollowing references are of record in the file of this patent:

20 UNITED STATES PATENTS IN umber Davis, Jour. Am. Chem. Soc., vol. '43; .-'2232 2233, 1921.

Davis, Jour. Am. .Chem. Soc vol. 43, n. 669. 5'40 1921.