US2472361A - Active halogen compounds and processes for their production - Google Patents

Description

Patented June 7, 1949 I ACTIVE HALOGEN COMPOUNDS AND PROC- ESSES FOR THEIR PRODUCTION William C. Arsem, Bethesda, Md.

No Drawing. Application October 30, 1944, Serial No. 561,166

9 Claims. 1

This invention relates to a process for preparing organic N-halogen compounds and to new compounds prepared by this process.

One object of the invention is to produce compounds having high percentages of active halogen in a state of high purity and with good yields.

Another object is to produce from organic compounds containing the groups =NH or --NH: other compounds in which all of the hydrogen atoms attached to nitrogen, which are herein called N-hydrogen atoms, or a predetermined fraction thereof, are replaced by active halogen atoms; and, in general, to produce from organic compounds containing a multiplicity of N-hydrogen atoms the corresponding N-halogen compounds in which all or a predetermined number of the N-hydrogen atoms have been replaced by active N-halogen atoms.

Some specific objects of the invention are the preparation of N-hexachlor melamine, N-hexaiodo melamine and other fully N-halogenated derivatives of the amides of cyanuric acid: also N- hexachlor triethylene tetramine and other N- halogenated polyethylene polyamines.

Some examples of N-halogen compounds are:

N-monochlor ethylamine, C2HNHC1 N-dichlor ethylamine, C2H5NC1: N-monobrom acetamide, CH1CONHBr N-iodo succinimlde, CzH4(CO)2NI N-chlor phthalimide, CeHdCOhNCl possible by such procedures to replace by active halogen all of the N-hydrogen in certain compounds.

The difiiculties encountered in producing completely N-halogenated organic compounds are due to their high reactivity. The N-halogen 2 compounds react with water according to the following equations:

m-Nx 11,0

In these equationsR may represent any radical attached to =NH or to -NH2, and X is a halogen atom. In the presence of an acid the equilibrium is displaced toward the left and there is very little hydrolysis. In an alkaline solution the equilibrium is displaced toward the right and a portion or even all of the active halogen may be removed.

Some N-halogen compounds in the presence of alkali undergo a non-reversible decomposition. The N-chloramides' and N-chlorimides of carboxylic acids are decomposed in alkaline solutions with elimination of the carbonyl group. For example, N-monochloracetamide yields methylamine CH3.CO.NHCl-l-NaOH CH3.NH2+NaC1+C0r and N-chlorphthalimide yields anthranilic acid C O OH NaCl CO! The N-halogen compounds act as oxidizing agents. For example, an N-chlor compound will react with an iodide in acid solution, one atom of positive chlorine setting free two atoms of iodine.

4- H O R-NH: HOX

R -NH. HOX

This reaction is made use of in analyzing N-chlor compounds to determine the percentage of active chlorine. Similarly, an N-chlor compound will oxidize hydrochloric acid or hydrobromic acid forming free chlorine or bromine.

It is evident that an organic N-halogen compound can be successfully prepared only under conditions permitting its survival, and that the while the second stage is the reaction or hypochlorous acid with the N-hydrogen compound R-NH: H001 R-N II the N-hydrogen compound does not have a basic character, the hydrochloric acid will accumulate in the mixture until the destruction of the N-chlor compound by the reaction just balances its rate of formation, and under these conditions very little oi the N-chlor compound will be formed. It the N-hydrogen compound has a basic character, a portion oi it will serve to neutralize some of the hydrochloric acid, but the portion so utilized will not be available for N-chlorination. In either case a low yield will result, and it the N-hydrogen compound contains more than one replaceable N-hydrogen atom in the molecule, only a partially N-halogenated compound will be obtained.

If an alkaline substance is added to neutralize the hydrochloric acid another difllculty arises. In partly N-halogenated compounds or the type the N-hydrogen is acidic because of the presence of the halogen atom, and the acid character is enhanced if the radical R contains an acidic group such as :00 or $02. In compounds containing more than group, the introduction oi N-halogen into one of these groups confers a more acid character upon the N-hydrogen of the other =NH groups especially if they are near each other in the molecule. In alkaline liquids therefore, the residual N-hydrogen or a partially N-halogenated compound derived from an N-hydrogen compound containing one or more NH: groups or a plurality of NH groups is more readily replaced by a metal than by a positive halogen, and it is impossible to eflect complete N- halogenation of such compounds in alkaline solutions.

When melamine suspended in water is treated with chlorine, the initial reaction between chlorine and water produces hypochlorous and hydrochloric acids, then some or the melamine reacts with hypochlorous acid to form, partially N-chlorinated derivatives, while another portion of the melamine combines with the tree hydrochloric acid to form a salt. For each molecule of hypochlorous acid which reacts with an N-hydrogen atom to replace it with an N-chlorine atom, one molecule of hydrochloric acid must be neutralized, and for this purpose one basic --NI-I2 group must be available. It is impossible under these conditions to introduce more than a small proportion of the theoretically possible six .N-chlorine atoms into a molecule of melamine. Free melamine must be present to act as a base for the fixation of hydrochloric acid, and it is not possible to chlorinate completely a portion of the melamine while some of it remains free of N- chlorine and retains a basic character. The product resulting from the chlorination of a water suspension of melamine is therefore a mixture of the lower chlorinated derivatives.

A similar result is to be expected from attempts to chlorinate in the presence of water, using elementary chlorine, any N-hydrogen compound of the melamine group having more than one replaceable N-hydrogen in the molecule, such as ammeline or ammelide, or, in general, any compound containing a plurality of N-hydrogen atoms, and only partially N-chlorinated compounds can be obtained in this manner.

If an alkaline substance, such as sodium or calcium hydroxide, is added to the reaction mixture when attempting to chlorinate melamine in water suspension, water-soluble derivatives of partly N- chlorinated melamine are formed. These soluble derivatives probably contain the grouping in which M stands for one equivalent of the metal corresponding to the alkaline hydroxide which was added. From such a water-soluble derivative, a mineral acid will set free a partly N-chlorinated melamine.

The impossibility of efiecting complete N-halogenation of an N-hydro'gen compound in water suspension by treatment with an elementary halogen either with or without the addition oi an alkaline hydroxide is illustrated by data presented in U. S. patents numbered 2,184,883, 2,184,886 and 2,184,888 in which incompletely halogenated melamines are obtained by halogenation oi melamine in water. Specifically, in Patent 2,184,883, Example #I describes the chlorination of melamine in aqueous suspension yielding a product containing 74% active chlorine. This amount of active chlorine corresponds to two atoms of N- chlorine in the molecule, whereas if six atoms, the possible maximum number, had been introduced, the product would have contained 128% of active chlorine. Example III of Patent 2,184,886 and Example VII of Patent 2,184,888 describe the chlorination of a melamine suspension containing calcium hydroxide which yielded a product containing 88.5% active chlorine corresponding to 2.8 atoms of N-chlorine in the molecule. Example I of Patent 2,184,888 describes the bromination of melamine in Water which gave a product containing 112% active bromine, corresponding to only two atoms of N-bromine in the molecule instead of the maximum possible number, six. Example 11 of the same patent describes the treatment of melamine with a solution of iodine in sodium hydroxide which gave a product containing less than two atoms of active iodine in the molecule.

The failure in these examples to obtain completely N-halogenated compounds containing six atoms of N-halogen in the molecule was due to the conditions of the reaction, and not to limiting the duration of the process.

I have found that N-halogen derivatives of organic nitrogen compounds which contain replaceable hydrogen attached to nitrogen may best be prepared by reacting such N-hydrogen compounds with hypohalogen acids in weakly acid solutions. Such weakly acid solutions may be obtained by using acids with small dissociation constants, or by buffering acids of greater strength.

A convenient way of employing this method to produce N-chlor compounds is to use a solution of sodium hypochlorite to which acetic acid in excess has been added. Such a solution is an efiective agent for the introduction of active or positive chlorine in place of N-hydrogen in organic compounds. Another way of producing a chlorlnating solution of this type is to pass gaseous chlorine into a solution of sodium acetate.

Similarly, solutions of sodium hypobromite or sodium hypoiodite acidified with acetic acid in excess may be used for the introduction of the corresponding active halogens into N-hydrogen compounds, and equivalent solutions may be obtained by treating solutions of sodium acetate with elementary bromine or iodine. Instead of acetic acid, other acids not readily oxidized or halogenated may be used, for example propionic acid or chloracetic acid.

In carrying out the process the N-hydrogen compound may be dissolved, suspended or emulsified in water and the halogenating solution added. Alternatively, the N-hydrogen compound may be mixed with acetic acid or other suitable acid and then the solution of hypohalite added, whereupon the hypohalogen acid is set free and reacts with the N -hydrogen compound to produce the N-halo-compound.

The reaction is practically quantitative andcan be used to replace all or a definite proportion of the replaceable hydrogen in an N-hydrogen compound by active halogen. The proportion of halogen introduced is determined by the amount of active halogen supplied as hypohalite in relation to the amount of N-hydrogen compound to be N- halogenated. For instance, melamine, which has six N-hydrogen atoms, can be N-halogenated by the methods described to yield distinct compounds containing from one to six N-halogen atoms.

The reaction is of general applicability to N- hydrogen compounds, including primary and secondary amines ofthe aliphatic and aromatic series, amides and imides of carboxylic or sulphonic acids, amino acids, heterocyclic ring compounds such as melamine, ammeline, ammelide and azines of various types and substitution derivatives thereof containing alkyl, alkoxyl or acyl groups, melam, melem, melamine resins, urea' process is the production of N-hexachlor melamine in which all the N-hydrogen atoms of melamine are replaced by active chlorine. In carrying out the process, melamine in pulverized form is treated with a weakly acid solution containing hypochlorous acid. This may be done in several ways. Melamine may be suspended or dissolved in water containing acetic acid and a solution of hypochlorous acid added. A sodium hypochlorite solution may be added to a suspension of meh- I mine in water containing enough acetic acid to liberate all the hypochlorous acid, with an additional amount of acetic to maintain an acid reaction, that is, a pH- less than 7. N-hexabrom melamine and N-hexaiodo melamine can be produced by analogous procedures. partial N-halogenation of melamine can be efiected by employing suitable proportions of the reacting components. N-hexachlor melamine may be used as an agent for effecting N -chlorination of melamine to produce derivatives containing less than six atoms of N-chlorine. For example, one molecule of N-hexachlor melamine will react with one molecule of melamine to give two molecules of N-trichlor melamine. N-hexachlor melamine may be used for the N- chlorination of N-hydrogen compounds other than melamine.

The structural formula of N-hexachlor melamine may be considered to be either of the following, or an equilibrium mixture of both.

According to the accepted practice in appraising commercial bleaching agents containing hypochlorites the active halogen content or the cas an index of comparison only when the compounds have the same kind of halogen. If an N-chlor compound and an N-iodo compound having the same active halogen content are compared, the N-chlor compound is more effective, weight for weight, than the N-iodo compound. If two compounds having the same number of active halogen atoms in the molecule are compared, the..N-chlor compound will be more effective, weight for weight, than the iodo compound although the latter will have a higher active halogen content. The difilculty in comparing active compounds containing diiierent halogens is due to the different atomic weights of the halogens.

A better basis for comparing different N-halogen compounds is the equivalent weight which is found by dividing the molecular weight of an N-halogen compound by twice the number of N-halogen atoms in the molecule. The lower the equivalent weight of a compound, the less will be required to produce a given quantitative effect.

The following table gives a list of important organic N-halogen compounds which can be made by the procedures outlined above with the equivalent weight and active halogen content of each. They are arranged in descending order of efiectiveness per unit weight as oxidizing agents,-

which is also the order of increasing equivalent weight. The active halogen content of each compound is also stated. Three commercial products 1 are included in the table: calcium hypochlorite, chloride of lime and Dichloramine-T Quantitative which is a commercial name for p-toluene suliondichloramide.

Active Molec- Active Equiv-' ular halogen alent 23;? weight atoms weight per e II-Eexachlor meliartrlilinle. 91.. 333 6 27. 75 128 xachlo e one e in f 353 6 29.4 120. 5 N-nonachlor melam 545. 5 9 30. 3 119. 6 N -tetrachlor ammeline. 205 4 33. 1 107 N-chlor methyleneurea. 141 2 35. 2 100. 7 N-dlchlor butylamine 142 2 35. 5 100.0 N-trichlor melamine 220. 5 3 38. 25 93 N-dichlor melamine 195 2 48. 75 72. 8 High-lest hypochlorite 70 Dichloramine-T 240 2 00 50. 2 N-dichlor dlethyl-barbituric acid 253 2 63. 2 56. 2 N-hexniodo melamine 882 0 73. 5 173 N-monochlor melamine 160. 5 1 80. 44. 2 N -ch1or phthelimide 181. 5 1 90. 7 39. l Chloride of lime.. N-brom hthalimide 226 l 113 71 N-iodo p thalirnide 273 1 136.7 91. 5 20 The highly halogenated substances produced by the methods herein described are particularly well adapted for the following uses:

a. Antiseptics.

b. Disinfectants.

c. Oxidizing agents.

d. Oxidation catalysts.

e. Drying agents for paints, oils, varnishes and 30 synthetic resins.

.f. Bleaching agents for fibres, textile materials, fats and oils.

0. Intermediate compounds for the preparation of other derivatives.

h. Chemical reagents.

To prepare antiseptic ointments or protective salves, these substances may be dissolved or dispersed in petrolatum, lanolin, hydrogenated oil, etc. To prepare disinfecting or decontaminating solutions they may be dissolved in organic solvents or aqueous alkaline liquids. They may be used as germicidal components of toilet preparations or medicinal products. They may be used in a substantially pure state or in admixture with other substances as a constituent of a dry mixture, paste, suspension or solution.

Since the completely N-halogenated compounds contain higher percentages of active halogen than the corresponding partly N-halogenated compounds, they are more effective and more economical to use.

The completely N-halogenated compounds are only very slightly soluble in water, but are soluble in organic solvents. They are generally quite stable for long periods, while the partly N-halogenated products are more soluble in water and less stable. Y

The first five products in the above tabulated list, which are completely N-chlorinated, are

especially valuable in applications such as those listed, and for which a compound having a high content of active chlorine is desirable.

The following examples illustrate the invention.

Example 1.Preparation of N-hexachlor melamine Melamine, 126 grams, is mixed with water, 2000 grams to form a suspension and 400 grams of acetic acid are added. The mixture is cooled to more acetic acid should be added until this is the 8 case. After the mixture has stood 30 minutes, with occasional agitation, the solid product is filtered oif, washed with water containing a little acetic acid, and dried at C. The product is a light, loose white powder with a faint yellow tinge. Analysis shows it to be substantially pure N-hexachlor melamine having the formula CsNeClc Its molecular weight is 333, it has an active chlorine content of 128%, and its equivalent weight as anoxidizing agent is one-twelfth of its molecular weight, or 27.75. It is practically insoluble in water, but soluble in benzene, carbon tetrachloride, ethylene dichloride, alcohol, kerosene and other organic liquids. It dissolves in aqueous alkaline solutions with an orange color, and from such solutions,,acids precipitate orange colored products containing a smaller proportion of active chlorine. Its use as a chlorinating agent to produce other N-chlor compounds is illustrated in Examples 1a and 1b in which lower N-chlor melamines are produced.

Example 1a.-Preparation of N-trichlor melamine Melamine, 126 grams, N-hexachlor melamine, 333 grams and water, 2,000 grams are mixed thoroughly. Then 20 grams of acetic acid are added, the mixture is heated at 50 C. for 30 minutes and allowed to cool. The solid product is separated, washed with water containing a little acetic acid and dried at 80 C. In the process, one molecule of melamine and one molecule of N-hexachlor melamine react to produce two molecules of N-trichlor melamine. Its formula is CaNeClaHa, its molecular weight is 229.5, its active chlorine content is 93 percent and its equivalent weight as an oxidizing agent is 38.25.

Example 1b.--Preparatz'0n of N-monochlor melamine In the same manner as in Example 1a, five molecules of melamine are caused to react with one molecule of N-hexachlor melamine to produce six molecules of N-monochlor melamine. Formula, C3N5C1H5; molecular weight, 160.5; active chlorine content, 44.2 percent; equivalent weight as oxidizing agent, 80.25.

Example 2.-Preparati0n of N-chlor phthalimlde Phthalimide, 147 grams, is mixed with water, 2,000 grams and acetic acid, grams. The mixture is cooled to about 20 C. and while stirring, an aqueous solution containing 80 grams of so- 5 dium hypochlorite is added. The pH is adjusted to less than 7 if necessary by adding more acetic acid. After the mixture has stood 30 minutes, the solid product is removed, washed with water containing a little acetic acid and dried at 80 C. The product is a fine white powder. It may be crystallized by dissolving in hot 50 percent acetic acid from which it separates on cooling in the form of small micaceous flakes. Formula molecular weight, 181.5; active chlorine, 39.1 percent; equivalent weight as oxidizing agent, 90.75.

Example 3.Preparation of N-dichlor butylamine Normal butylamine, 73 grams, is mixed with water, 750 grams and acetic acid 150 grams. To the solution of butylamine acetate containing an excess of acetic acid which is thus formed there is added, with cooling and stirring, an aqueous solution containing 150 grams of sodium hypochlorite in 5 percent solution. After one hour the colorless oily layer of N-dichlor butylamine is separated, washed and dried. Formula, C4H9NCl2; molecular weight, 142; active chlorine content, 100 percent; equivalent weight as an oxidizing agent, 35.5.

Example 4.-Prepa atin of N-hexachlor triethylene tetramine The procedure of Example 1 is followed, using triethylene tetramine, 146 grams, water 2,000 grams, acetic acid 450 grams and sodium hypochlorite 450 grams. The product is crystalline and has an active chlorine content corresponding to the formula Cl2N.C2H4.NCl.C2H4NCLC2H4NC12 Example 5.Preparati0n of N-nonachlor melam The procedure of Example 1 is followed, using melam in pulverized form 235 grams, water 4000 grams, acetic acid 600 grams and sodium hypochlorite 675 grams. The product is a buff-colored powder with an active chlorine content corresponding to the formula CsNnCls in which all nine atoms of N-hydrogen in melam, a deamination derivative of melamine, have been replaced by positive chlorine.

Example 6.--Preparation of N-chlorinated urea resin The procedure of Example 1 is followed, using pulverized or precipitated urea resin '72 grams, water 1,500 grams, acetic acid 150 grams and sodium hypochlorite 155 grams. The product is a white powder containing approximately 100 percent active chlorine.

Example 7.-Preparation of N-chlorinated casein Casein, powdered or freshly precipitated, -90 grams, is mixed with water,-1500 grams, and acetic acid, '75 grams, is added. The mixture is cooled and stirred while adding a solution containing '75 grams of sodium hypochlorite in 5 percent concentration. After the reaction mixture has stood for 30 minutes, the solid product is filtered off and dried at a low temperature. N-chlorinated casein is a pale yellowish white solid having an active chlorine content of about 57 percent.

Example 8.--Preparation of N-iodo succznimide Succinimide in fine powder, 99 grams, is mixed with water, 1000 grams and propionic acid 100 grams. The mixture is cooled and while stirring, a solution of 254 grams of iodine and 80 grams of sodium hydroxide in 6000 grams of water is added. After one hour the solid product is separated, washed and dried at a low temperature. Its formula is C2H4(CO)2NI; molecular weight, 225: active iodine content 112.9%; equivalent weight 112.5.

Example 9.-Preparation of N-hexachlor melamine Sodium acetate, 860 grams, is dissolved in liters of water. Chlorine is passed into the liquid unt l 440 grams have been absorbed. Then a suspension of 126 grams of melamine in one liter of water is added. The solid product is removed, washed and dried as in Example 1.

Example 10.Preparation of N-hexachlor melamine Melamine, 126 grams, is suspended in 10 liters of water in which has been dissolved 860 grams tinuously while chlorine gas, 440 grams, is passed in. The mixture is allowed to stand one hour, the solid product is filtered ofl, washed with very dilute acetic acid and dried at C.

Example 11.-Preparatz'on of N-hexabrom melamine The procedure of Example 1 is followed, using melamine, 126 grams, water, 2000 grams, acetic acid 400 grams and sodium hypobromite 750 grams in 5 percent concentration. The product is a yellow powder containing percent active bromine.

Example 12.Preparation of N-hexaz'odo melamine The procedure 0'! Example 1 is followed, using melamine, 126 grams, water, 2000 grams, acetic acid 400 grams and sodium hypoiodite 1050 grams in 5 percent concentration. The product is a yellow powder containing 173 percent of active iodine.

I claim:

1. The process of preparing an organic N- halogen compound which consists in reacting an organic N-hydrogen compound, which is decomposed by a hypohalite salt acting alone, with a hypohalogen acid in an aqueous solution having a pH below '7.

2. The process for the production of an organic N-halogen compound which consists in adding an aqueous sodium hypohalite solution to an organic N-hydrogen compound, which is decomposed by a hypohalite salt acting alone, in an aqueous solution of an excess of a weak acid.

3. The process of replacing by active halogen a definite proportion of the replaceable hydrogen attached to nitrogen in an organic compound which is decomposed by a hypohalite salt actin alone which comprises adding a regulated proportion of a hypohalite in water solution to an aqueous mixture containing the said organic compound together with sufficient acid stable toward positive halogen compounds to liberate all the hypohalogen acid from its salt and to ensure a slight acid reaction at the end.

4. The process of preparing an organic N- halogen compound which consists in adding a halogen to an aqueous solution of a sodium salt of a weak organic acid in presence of an organic N-hydrogen compound which is decomposed by a. hypohalite salt acting alone.

5. The process for the production of an organic N-halogen compound which consists in treating an organic N-hydrogen compound, which is decomposed by a hypohalite salt acting alone, with a halogenating solution obtained by adding a halogen to an aqueous solution of the sodium salt of an organic acid.

6. The process of preparing N-nonachlor melam which consists in adding an aqueous solution of sodium hypochlorite to a suspension of melam in an excess or aqueous acetic acid and separating the solid product.

'7. The process of preparing an N-halogen derivative of a urea-formaldehyde condensation product which consists in adding an aqueous solution of sodium hypochlorite to a suspension of a urea-formaldehyde condensation product in an excess of aqueous acetic acid and separating the solid product.

11 12 8. The process or preparing N-hexachlor tri- Number Name Date ethylene tetramine which comprises adding a 2,184,888 Muskat 5, 1939 solution 01 sodium hypochiorite to a solution of 2,299,089 Chenicek Oct. 20, 1942 triethylene tetramine in an excess or aqueous acetic acid and separating the solid product. OTHER mom 9. N-hexachlor triethyiene tetramine. Chattflway. h ur- (87) 1905. PP-

WILLIAM c. ARSEM. 145-171.

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