US2764602A - Quaternary ammonium alkylperfluoroamides - Google Patents

Description

Unite QUATERNARY AMlVIONIUlVI ALKYL- PERFLUOROAMIDES No Drawing. Application April 21, 1954,

' Serial No. 424,788

4 Claims. (Cl. 260-4045) This invention relates to my discovery of a new and useful class of reactive fluorocarbon compounds. These compound-s have utility as cationic surface active'agents, as surface treating and coating agents, as starting compounds for making'derivatives, and for other purposes.

These novel compounds are perfluoralkyl quaternary nitrogen compounds having in the molecule an intermediate amidopolymethylene linkage and uniquely characterized by having a terminal carbonyl-bonded perfluoroalkyl chain which provides a nonpolar saturated fluorocarbon tail that is both hydrophobic and oleophobic. This fluorocarbon tail is repellent not only to water but to oils and hydrocarbons and imparts unique surface active and surface treatment properties not possessed by corresponding compounds having a carbonylbonded hydrocarbon tail.

The invention provides surface active agents which have extraordinary activity in reducing by a large amount the surface tension of oils and waxes even when present in very small concentrations, notwithstanding that they are water-soluble as well as oil-soluble and are also highly eflective for reducing the surface tension of Water and aqueous solutions. This combination of properties is highly unusual. The corresponding non-fiuorinated compounds of conventional organic chemistry do not have significant surface tension reduction properties when dissolved in oils and waxes, although they may have a high degree of activity in water and aqueous solutions when the hydrocarbon chains are of suflicient length. So far as I am aware, there are no non-fluorinated surface active agents capable of markedly reducing the surface tension both of Water and oils at low concentrations; nor is this a general characteristic of fluorinated surface active agents.

My perfluoralkyl-amidopolymethylene quaternary nitrogen compounds constitute a class of related compounds that can be represented by the generic formula:

[CnFz1t+1CONH-( CH2) m--NQ] +A- and by the equivalent formula for normal compounds:

trostatically bonded to the quaternary nitrogen atom.

NQ is a terminal oleophilic organic cationogenic group united to the polymethylene linkage and contains a quaternary nitrogen atom (N) covalently bonded to hydrogenated carbon atoms and electrostatically bonded to atent ice quaternary nitrogen atom by means of carbon-nitrogen bonds and is linked through this nitrogen atom to the polymethylene linkage. It is this cationogenic group that causes the organic chain to be a cation having a positive charge at the quaternary nitrogen position.

As is clearly evident from the above structural formulas, the complete molecule consists of an anion (negatively charged) electrostatically united to a long-chain cation (positively charged owing to the positive charge of the quaternary nitrogen atom). When dissolved in water or other suitable ionizing solvent, the ionized molecules provide long-chain surface-active free cations which have a terminal nonpolar fluorocarbon tail that is both hydrophobic and oleophobic. The intermediate amido linkage to which the fluorocarbon tail is united enhances solubility of the molecule in water and other polar solvents. Ihe polymethylene chain provides a stable linkage between the nitrogen atom of the amido group and the quaternary nitrogen atom and also serves to enhance solubility in' oils and waxes. The terminal organic Q structure united to the quaternary nitrogen atom renders the cation or complete molecule oil-soluble at this end. The quaternary nitrogen atom imparts greatly increased solubility in water and other ionizing solvents. Thus the molecule is water-soluble and oil-soluble, and is oleo- "phobic at one end and olephilic at the other end. It is repellent to water, oils and hydrocarbons at the fiUOIO.

carbon end and yet is soluble therein at the quaternary nitrogen end.

This makes possible molecules that can be dissolved both in water and in oils and waxes and yet will concentrate at the surface to form an oriented surface layer having the fluorocarbon tails pointing outwardly. A surface results that is outwardly nonpolar and is both' water and oil repellent, and which greatly reduces the surface tension.

the anion (A), Q representing an organic terminal 1 structure which satisfies three of the covalencies of the the fluorocarbon tails oriented outwards to provide a nonpolar fluorocarbon outer surface.

These fluorocarbon quaternary nitrogen compounds provide surface active agents that are highly effective in water and in neutral, acidic and basic aqueous solutions, serving to greatly reduce the surface tension even when present in minute concentrations. The fluorocarbon tail provides a hydrophobic chain that can be even more effective in aqueous solutions than is a much longer hydrocarbon chain such as is employed in corresponding compounds of conventional organic chemistry. Thus a fluorocarbon tail 'containing'7 carbon atoms (a perfluorocapryl chain) is even more effective for this purpose than is a hydrocarbon tail containing 17 carbon atoms (a stearyl chain).

The present compounds provide surface active agents which have amazing utility as additives for oils and Waxes and greatly reduce the surface tension even when present in minute proportion. A high degree of surface tension reduction can be achieved at concentrations of 0.1% by weight or less in animal, vegetable and mineral oils and waxes (the latter being in a dissolved or molten state), including petroleum solvents, gasoline, kerosene, fuel oils, lubricating oils, and parafiin waxes, thereby, for instance, improving such properties as surface protection, flow, spreading, penetration, and atomization or sprayability.

These compounds also have utility as emulsifying agents for fluorocarbon-s and oils (the agent collecting at the interfaces with the fluorocarbon tails dissolved in the fluorocarbon phase and the other portions of the molecules dissolved in the oil phase). Theycan be'used as emulsifying agents for fluorocarbon-water systems.

Other factors remaining the same, the solubility of the present compounds both in water and in oils. decreases.

bonyl-bonded hydrocarbon tail decreasesas to. water;

solubility. but increase as to oil solubility with. increase in length of this chain.

The properties of the compounds can be varied to best serve a desired particular use by varying tbelength. of the fluorocarbon tail, the length of the. intermediate polymethylene chain, and the nature of the nitrogenbonded Q structure. However, it is critical that the molecule have :a fluorocarbon tailf containing at least.

three carbon atoms and the preferred number isi5:.to 111'.

It is also of critical importance that;the. fluorocarbon chain be free from hydrogen atoms, In particular, the presence of even one hydrogen atomon: the last. or next to last carbon atom of the tail will markedly alter the surface active and solubility properties, reducing surface activity and the hydrophobic and oleophobic characteris-. Hydrogen. is electropositivewhereas fluorine is strongly electponegative, hence. the

tics of surface coatings.

presence of hydrogen and fluorine in,the,terminal portion of the tail renders it polar instead of nonpolar; and also,renders the tail less stable to heating owing to the opportunity for dehydrofluorination and provides opportunity for chemical attack.

In general, the halide salts and sulfate salts are most convenient and useful to employ as surface active agents; and they can be readily prepared by processes illustrated in the subsequent examples. In dry form the simpler halide salts ar solid crystalline ionic substances. They are stable and are soluble to sparingly soluble in water and in oils (the solubility decreasing with increase in number of fiuorinated carbon atoms).

The correspondinghydroxides can be obtained by re-.

It is. a feature of my compounds that a wide varietyof oleophilic cationogenic groups (NQ) can be em-.

ployed, cyclic as well as noncyclic. This portion ofthe molecule is the same as in the corresponding quaternary.

compounds of conventional organic chemistry, the distinctive fluorocarbon tail being at the otherend of the molecule, and a wide variety will be evident to those skilled in the :art of quaternary surface active agents.

Thus the quaternary nitrogen atom can be bonded to three hydrocarbon side groups, forming quaternary ni,

trogen compounds of the type:

where R, R" and R are hydrocarbon groups, such as alkyl, cyclohexyl, alkaryl and aryl groups. Preferred compounds of this type are those in which R and R" are alkyl groups each containing one to six carbon atoms (1': e., methyl, ethyl, propyl, butyl, amyl or hexyl groups),

and R is astable oleophilic hydrocarbon group, such as and the nitrogen atom is also bonded to a side group,

is predominately cationic and basic.

4 for instance an alkyl group, as illustrated by compounds of. the following p The above compounds can be readily prepared from the corresponding amine starting compounds which contain a trivalent nitrogen atom, by quaternizing with a compound of the RA type which provides the nitrogenbonded R group and A anion of the product, as by using a halide or a sulfate quaternizing agent.

A further type of compound is represented by the above formulas when the R group is a normal alkylenecarboxyl group, i. e., an N-bonded normal alkyl chain in which the terminal methyl group has been replaced by an anionogenic carboxyl group; the terminal carboxyl group thus being united to the quaternary nitrogen through a methylene or polymethylene linkage containing oneto six carbon, atoms. These compounds can be made by quaternizing with a halogenated monocarboxylic acid, such as chloroacetic acid. The corresponding specific formulas of thesecompounds are:

a positivecharge at thequaternary nitrogen position, and.

itisacidic and has a negative charge at the carbonyl position. In strongly acidic solutions, ionization occurs mainly at the quaternary nitrogen position and the molecule In strongly basic solutions, ionization occurs mainly at the carboxyl position and themoleculeis predominately anionic-and acidic. In the weakly-acidic toweakly-basic range, the ionized molecule shifts from being predominately cationic and basic to being predominately anionic and acidic, but always has both characteristics in appreciable degree since the ionization sites are separated in the molecule. The carboxyl group is, hydrophilic and increases the watersolubility of the molecule, but it does not prevent the NQY: structure; from being oleophilic as a Whole.

Theparboxyl hydrogen atom can be substituted by a metal atomloform salts (e.. g., the sodium and potassiunrsalts) and the .carboxylate group in such compounds is also hydrophilicand anionic. Hydrolysis in acidic solutions yields the, corresponding acid.

The carboxyl hydrogenatom can be substituted by an allsyl group toiormesters (e. g., the methyl and. ethyl esters). ing with a halogenated monocarboxylic ester (such as methyl .chloroacetate) ing acid,

Thesecarhqxylic acid, salt, andcster compounds inap- The esters. can be made directly by quaterniz-v Hydrolysisyields the correspond.

propriate aqueous solutions all yield i'onized molecular structures which can be represented by the generic formula:

( HghOOO' H2 COOH Corresponding salts and esters can also be prepared.

The quaternary nitrogen atom can be present in a pyridine ring, which satisfies the three available valencies, thus providing quaternary pyridinium compounds:

This type of compound can be readily made by reacting pyridine with a perfluoroalkyl-amidopolymethylene halide.

The following table lists illustrative quaternary compounds that have been prepared and shows the remarkable reductions in surface tension produced when a minute amount is dissolved in water, in oils and in a Wax; the first row giving the surface tension values thereof in the absence of the additive. The formulas are given in a simplified or abbreviated form but can be readily related to the kind of structural formulas used elsewhere. All values were measured at 25 C. except in the case of the wax, which was a micro-crystalline type paraflin wax and the surface tension values were measured at 100 C. with the wax thus being in a melted fluid state.

These tertiary amine starting compounds are described in more detail and are claimed in my companion application filed of even date herewith, S. N. 424,789.

The following illustrative experiment relates to the specific reaction: c1r.5o0NHc,n@N oH, can

CH3 C7F15CONHC:HoN CH3 I CH2 In this example, N,N-dimethyl-N'-perfluorocaprylarnidopropyleneamine is reacted with methyl iodide to make trimethyl (gamma-perfluorocaprylamido)propylene ammonium iodide, which has a fluorocarbon tail containing seven carbon atoms.

A 1000 ml. l-necked flask was charged with 426 grams (0.965 mole) of ethyl perfluorocaprylate,

CrFisCOOCzHs and 200 ml. of absolute diethyl ether. The flask was cooled in an ice bath and 98.2 grams (0.965 mole) of dimethylaminopropyleneamine, H2NC3HeN(CI-Ia)2, was added slowly enough to maintain a temperature below 35 C. in the flask. The flask was removed from the ice bath, allowed to warm to room temperature, and was then placed under a 5 plate column for vacuum distillation. As the reduced pressure was slowly applied, the ether distilled off to leave the above-mentioned perfluorocapryl amine product which was distilled off at about 20 mm. vacuum at the boiling range (154-158 C.). A total of 440 grams (0.882 mole) was obtained. The refractive index was 1.3559. The 440 grams of this product was mixed with 1000' ml. of absolute diethyl ether and 213 grams of methyl iodide (1.5 moles) in an unstoppered 3000 ml. Erlenmeyer flask, and left standing overnight. The quaternary ammonium iodide salt product was dried by pouring the reaction mixture into a large evaporating dish which was placed in a hood draft to evaporate off the ether. The dried salt was a free-flowing whitepowder, which dissolves easily in water, and which has a melting point of 148150 C.

SURFACE TENSIONS (DYNES/ CM.) WITH AND WITHOUT ADDITIVES 9 Min- Lin- Melted Water eral seed Wax Oil Oil Value without additive 72 31 32 27 Amount of additive (percent by wt.) 0.05 0. 1 0. 1 0. 1

H I n rscoNH N(CH I O7F 5CONHC3HAN(CH3)2(CH3G0H5) O1 The preparation of the 3d, 9th, 10th and last compounds listed above are specifically described in the following Examples 1, 2, 3 and 4, respectively.

Example 1 It was identified as the desired compound mentioned above. "Analysis showed 4.33% N (calc. 4.37%) and 19.9% I (calc. 19.8%). i

Data indicating the powerful surface activity of this compound have been given in the preceding table. Its water-solubility and strong surface tension reduction activity in water are in diametric. contrast to the tertiary amine starting compound. Further illustration of surface activity is provided by the following demonstration experiments:

(A) A clean glass slide was coated with a thin film of water. A speck of the quaternary salt was dropped on the film and it caused an immediate separation of the film and a dry area was formed on the glass. The glass in this area had become plated with the cations and the added to the water, causing the "water to spread out to an area of 3.45 sq. cm., owing to the reduction in surface tension.

(C) A 1% (by weight) solution of the quaternary salt in water was prepared. When a drop was placed on a sheet of writing paper, complete penetration occurred in a few seconds. The sameresult was obtained using a piece of nylon cloth and a piece of cardboard, penetration in these cases being almost instantaneous. Drops of pure water when applied to these materials did not penetrate. Thus the quaternary salt served as a highly effective wetting agent. I

This compound in minute proportion (e. g., 30 p. p. m.)

greatly inhibits the evaporation of volatile hydrocar-- bons, such as gasoline, owing to formation of a surface barrier film.

In the above example, the methyl iodide reacts readily in a mild'exothermic reaction and no heating is required. The use of methyl iodide as a quaternizing agent is convenient in laboratory work because it readily reacts and it is a liquid at room temperature, whereas the other methyl halides (methyl bromide, methyl chloride and methyl fluoride) are gases at room temperature. and must be reacted in a pressure vessel. The higher halides which are liquid at room temperature can be conveniently employed, although heating is generally required because they react more sluggishly.

Thus the same perfluorocapryl amine that was employed in the above example was quaternized with benzyl chloride and with n-decyl bromide. In both cases the reaction mixture was heated for 2 hours at 100 C., and the solid salt product was washed with ether to remove unreacted material, and dissolved in water. Data on the quatearnary product compounds are included in the foregoing table.

Similarly, amine starting compounds in which the nitrogen atom of the terminal amine group is a member of a heterocyclic ring (e. g., a piperidine ring or a morpholine ring) which satisfies two valence bonds, can be quaternized with a hydrocarbon halide.

Example 2 In this example, beta-perfluorocaprylamidoethylene chloride is reacted with pyridine to yield beta-perfluorocaprylamidoethylene pyridinium chloride.

A 250 ml. Erlenmeyer flask cooled in an ice bath was charged with 100 ml. of absolute diethyl ether and 44.2 grams (0.1 mole) of ethyl perfluorocaprylate,

C'IFI5COOC2H5 Then 6.1 grams (0.1 mole) of ethanolarnine,

H2NC2H4OH was slowly added and the mixture was left standing for one hour. The mixture was poured into a fiat evaporatexhibited strong surface active properties.

ing dish and the ether and alcohol allowed to evaporate. The product, obtained in a quantitative yield of 45 grams, was a white crystalline solid having a melting point of -82 C., and was identified as the amido alcohol derivative, C7F15CONHC2H4OH. A 50 ml. 1- necked flask topped by a reflux condenser Was charged with 22.5 grams (0.05 mole) of this amido alcohol and 6-grams (0.5 mole) of thionyl, chloride, ,SOClz. The mixture was refluxed for30' minutes and poured into, coldwater. The white solid separating was filtered out, washed with cold water, and air-dried overnight. The yield was quantitative. This product was identified as the desired beta-perfiuorocaprylamidoethylene chloride. It was converted to the desired quaternary salt by overnight refluxing with pyridine, using equal parts by weight mixed with 10 parts water. The product was a homogeneous solution of the quaternary pyridinium chloride salt, and the latter could be obtained in free form by evaporating the Water.

The extreme surface activity of this quaternary pyridiuium salt. is indicated by the fact that it reduces the surface tension of water at 25 C. from 72 to 18 dynes/cm. at a concentration of only 0.005% by weight (50 mgrper liter), and to 15 dynes/ cm. at a concentration of 0.01%. It reduces the surface tension of kerosene at 25 C. from 26 to 21 dynes/cm. at a concentration of 0.1%. Other data are given in the foregoing table. This compound has been found to be highly effective as an ore flotation agent.

Example 3 This example illustrates theuse of sulfates as quaterniziug agents in place of using halide agents that have been illustrated in Example 1. Specifically, N,N-diethyl- N-perfiuorocaprylamidoethyleneamine is reacted with dimethyl sulfate to make methyldiethyl(gamma-perfluorocaprylami-do)ethylene ammonium methylsulfate:

C 7F sCONHC;H4N CgHs CHsSOF A ml. Erlenmeyer flask was charged with 5.12 grams (0.01 mole) of the above-mentioned amine and then with 1.26 grams (0.10 mole) of dimethyl sulfate. A very exothermic reaction resulted and the mixture solidified. The solid product was dissolved in water and Data are given in the foregoing table.

Example 4 A 250 ml. Erlenmeyer flask was charged with 15.5 grams (0.03 mole) of the N,N-diethyl-N'-perfluorocaprylamidoethyleneamine and then with 2.8 grams.

(0.03 mole) of chloroacetic acid, and the mixture was heated to -450 C. Upon cooling, the viscous liquid product solidified at about 5560 C., forming a lightbrown water-soluble solid having strong surface active properties. Data are given in the foregoing table.

I claim: 1. The new and useful perfluoroalkyl amidopolymethylene quaternary ammonium compounds represented by the formula:

where n has an integer value of 3 to 11, m has an integer value of 2 to 6, A is an anion, R and R" are alkyl groups each containing 1 to 6 carbon atoms, and R is an alkyl group containing 1 to 17 carbon atoms.

3. The new and useful perfluoroalkyl-amidopolymethylene quaternary ammonium compounds represented by the formula:

where n has an integer value of 3 to 11, m has an integer value of 2 to 6, A is an anion, R and R are alkyl groups each containing 1 to 6 carbon atoms, and the CHzCsHs group is a benzyl group.

4. Trimethyl(gamma perfiuorocaprylamido)propyl ene ammonium iodide, having the formula:

C'ZF15CONHC3H6N(CH3)3I 2mm References Cited in the file of this patent UNITED STATES PATENTS 2,567,011 Diesslin et a1. Sept. 4, 1951 2,568,500 Husted et a1. Sept. 18, 1951 2,593,737 Diesslin et a1. Apr. 22, 1952

Claims (2)

1. THE NEW AND USEFUL PERFLUOROALKYL - AMIDIPOLYMETHYLENE QUATERNARY AMMONIUM COMPOUNDS REPESENTED BY THE FORMULA:

4. TRIMETHYL(GAMMA PERFLUOROCAPRYLAMIDO)PROPYLENE AMMONIUM IODIDE, HAVING THE FORMULA: