US2256759A - Amidine salts of aminobenzoic acids - Google Patents

Description

Patented Sept. 23, 1941 AMIDINE SALTS or AMINOBENZOIC ACIDS I Garnet Philip Ham, Old Greenwich, Conn., as-

signor to American Cyanamid Company, New- York, N. Y., a corporation of Maine No Drawing.

Application September 28, 1939,

Serial No. 296,916

Claims.

This invention relates to amidine salts of aminobenzoic acids such as anthranilic acid and metaand para-aminobenzoic acids and to methods of preparing the same. I have found that certain well-defined amidine salts of these aminobenzoic acids can be formed, which salts have unusual properties of considerable commercial importance. They exert a remarkable stabilizing action on photographic developing solutions when incorporated therein.

The amidines which I have found to form salts with aminobenzoic acids may be defined as amino-amidines; that is to say, amidines in which the alkyl or aryl group has been replaced by an amino or substituted amino group. The compounds may therefore be represented by the type formula I R RzN C INR3 in which R1, R2 and R3 are members of the group consisting of hydrogen, alkyl, hydroxyalkyl and aryl radicals and X is a member of the group consisting of R1,

OzNRrRz and The substituents R1, R2 and R3 may be the same or different in various compounds included within the scope of the invention and it should be understood that each symbol is intended to represent any member of the group defined.

The amidine salts represented by the above type formula are true addition products; that is to say, the carboxylic acid group adds on to the organic base to form a salt. I believe that this addition takes place at one of the nitrogen atoms of the amidine, which undergoes a change of valence of from 3 to 5, but this fact has not as yet been definitely established for any of the salts of organic nitrogen bases. Accordingly, the above formula represents the customary method of designating addition products of this nature, this method consisting simply in showing the formula of the base in juxtaposition to the formula of the acid.

An inspection of the above type formula will show that the amidine salts of my invention are salts of guanidine and its derivatives and substitution products, and particularly guanidine itself, guanylurea, biguanide, and their alkyl, hy-

droxyalkyl and aryl substitution products. These compounds are all organic bases, and are sufficiently basic to enable them to form salts with aminobenzoic acids such as anthranilic acid.

Any guanidine base may be used for this purpose, such as guanidine itself, dimethyl or trimethyl guanidine, dibutyl guanidine, mono-, dior triphenyl guanidine, ditolyl guanidlne, or alkoxy substituted guanidines such as mono-, dior triethanol guanidine and the like. Similarly, such guanylurea compounds as guanylurea itself, monoor dimethyl guanylurea, diphenyl guanylurea, tetraethyl guanylurea, and triethanol guanylurea are organic bases which will form salts of anthranilic acid and metaand paraaminobenzoic acids.

Biguanide and such substituted biguanides as monoand dimethyl and diethyl biguanides, diamyl biguanide, 1.5 diallyl biguanide, 1.1.5.5 tetramethyl biguanide, 1.1.2 trimethyl biguanide and 1.2.3 triphenyl biguanide will also form salts of aminobenzoic acids in accordance with themvention. It should be noted however that the biguanides, as well as the other amidine bases included in the invention, will form both neutral and acid salts with 'dibasic mineral acids such as sulfuric acid. These two classes of salts will, in turn, form salts containing one and two molecular equivalents of anthranilic acid for each mole of the biguanide or other amidine compound respectively. It should .be' understood that both classes of salts are included in the invention.

Many of the salts of my invention may be prepared by simply mixing a solution containing the free amidine base or its carbonate with a solution of aminobenzoic acid such as an anthranilic acid solution. In many cases it is convenient to start with the amidine sulfate, hydrochloride or other mineral .acid salt, from which the free base can be liberated by dissolving in alcohol, addition of an alkali such as sodium hydroxide, and removal of the precipitated sodium sulfate, sodium chloride or other salt.

The invention will be illustrated in greater detail by the following specific examples. It should be understood however that although these examples describe certain compounds constituting specific embodiments of the invention they are given primarily for purposes of illustration and the invention in its broader aspects is not limited thereto.

Example 1 164 parts of 98.2% guanidine carbonate are dissolved in parts of warm water and the C. and filtered,

The residue is dissolved in 125 parts of hot 1 water, cooled to about 25 C. and the crystals are l filtered off and dried at room temperature. The 3 product'is guanidine tinthranilate, a. light-grey crystalline salt consisting of stout bevelled prisms of parallel extinction. The index of refraction parallel to length is about 1.514; across the: f 1 length it is about 1.648. On long and continued 1 exposure to light the crystals become slightly ;yellow. 1

1 1 The molecular weight of the new salt i s 2f14=; 3 It melts at 65-66 C.', and is soluble in' water to' the extent of 133 g. per 100 g. ofwater at 25 C. 3 A 1 g. solution in 100 cc. of water exhibitsa pH 5 at 25 C. of 5.93 and a potential of +0.07 yolt 1 Its analysis is shown in the following table:

. Percentage Component V Theor. Det.

Carbon (0) Hydrogen (H) 'lFrom Lthe analysis and. molecular weight it is Qe vident that the empirical formula of the compOIllIld is CN3H5.HOOC.C6H.NH2.H20.

Upon substituting for the guanidine equivalent solublefiinwater than is the extremelysoluble fglu'anidine a nthranilate, but they are more's oluble iin organicl' solvents fsu ch' asfetha'nol, solvent Tnaphth'a n the use. The diphenyl anddixylyl 'guanidinejlanthranilates were found to be effecjt ve as r'nothproofingagents when prepared as a' gffl'fisolutign in solvent naphtha.

Example 2 parts byweightof 'biguanide sulfate were dispersed in 400 parts byvolume of ethyl alcohol, 3:32 'parts;by -weight ofsodium hydroxide were added andsthe mixture stirred for about 6 hours i to insure 1 complete. reaction. The precipitate of sodiumsulfate. was then filtered off, leaving a solutioniof free biguanide in alcohol. {solution there was added with stirring 54.8 parts To this :ofvC. P. anthranilic acid, whereupon heat was generated.and a clear solution was obtained. QiUp'on standing, crystals of biguanide anthranilate separated out, .The mixturewas then stirred,

jfiltered, and the crystalswere washed with ethyl alcohol and dried under a vacuum.

Biguanide anthranilate is a. white crystalline -:sa1t consisting of'thin plates; sometimes octag- The index of refraction parallel to cates that the crystals are anhydrous. Its analysis is shown in th following table:

145.2 parts by weight of guanylurea sulfate were dispersed -inYflOO parts by volume of ethyl alcohol. 16 parts by weight of sodium hydroxide were added and the mixture stirred for four hoursto insure complete reaction of the guanylurea sulfate. The precipitate of sodium sulfate was then filtered off.

54.8 parts by weight of C. P. anthranilic acid were'added to the filtrate with continuous agitation. The mixture wasthen stirred for one hour, the solids filtered off and Washed with ethyl alcohol, and the resulting crystals dried in 'vacuo for aboutten hours.

.Guanylurea,anthranilateis a white crystalline salt consisting of longslender prisms of parallel extinction. The index of refraction parallel to the length is about 1.535; across the length it is about 1.697. The crystals become slightly yellow upon long and continued exposure to light. They melt at. 159-160 C. and are soluble in water to the extent of 2.3 g. per cc. at 25 C. A1% solution in water exhibits at 25 C. a pH of 6.43 and a potentialrof +0.07 volt. The molecular weight is 239, which indicates that the crystals are anhydrous. The analysis of the product is shown in the following table:

What I claim is: 1. Salts of aminobenzoic acids of the formula RlRzN cams .HOOC.CH4.NH2

in which R1, R2 and R3 are members of the group consisting of hydrogen, alkyl, hydroxyalkyl and aryl radicals and X is. a member of the group consisting of R1, 7

and

RENINRlR? 2. Salts of aminobenzoic acids of the formula lRaN CzNRa 11000 I HN' HIN aryl radicals and X is a member of the group consisting of R1,

I RsNiCNRqRz 3. Salts of aminobenzoic acids of the formula RiRzN RiRnN in which R1, R2 and R3 are members of the group consisting of hydrogen, alkyl, hydroxyalkyl and aryl radicals.

4. Salts of aminobenzoic acids of the formula in which R1, R2 and R3 are members of the group consistin of hydrogen, alkyl, hydroxyalkyl and aryl radicals.

' 5. Salts of aminobenzoic acids of the formula in which R1, R2 and R3 are members of the group consisting of hydrogen, alkyl, hydroxyalkyl and aryl radicals.

6. Salts of aminobenzoic acids of the formula HIN C l ZN in which R1, R2 and R3 are members of the group consisting of hydrogen, alkyl, hydroxyalkyl and aryl radicals.

7. Salts of aminobenzoic acids of the formula in which R1, R2 and R3 are members of the group consisting of hydrogen, alkyl, hydroxyalkyl and aryl radicals.

8. Salts of aminobenzoic acids of the formula in which R1, R2 and R3 are members of the group consisting of hydrogen, alkyl, hydroxyalkyl and aryl radicals and X is a member of the group consisting of R1,

I O I CNR1R2 and RsN: CNRlRz with a solution of an aminobenzoic acid and separating the resulting compound from the solvent.

GARNET PHILIP HAM.