US 2759019 A
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United States Patent i PERFLUORO AMINE COMPOUNDS AND QUATERNARY DERIVATIVES Harvey A. Brown, St. Paul, and Arthur H. Ahlbrecht,
White Bear Township, Ramsey County, Minn., assignors to lvliunesota Mining & Manufacturing Company, St. Paul, Minn., a corporation of Delaware No Drawing. Application August 9, 1954, Serial No. 448,734
'2 Claims. (Cl. 260-556) This invention relates to our discovery of a new and useful class of reactive fluorocarbon compounds. These compounds have utility as surface active agents, as surface treating and coating agents, as starting compounds for making derivatives, and for other purposes.
These novel compounds are fluorocarbon dialkylamines and their corresponding quaternary ammonium derivatives, uniquely characterized as to structure by having in the molecule a terminal sulfonyl-bonded fluorocarbon tail" that is both hydrophobic and oleophobic.
More specifically, our fluorocarbon-type amines may be termed perfluoroalkaneesulfonamidopolymethylenedialkylamine compounds and are represented by the generic formula:
where R1: is a perfluoroalkyl chain (CnF2n+1-) containing 5 to 12 carbon atoms, in (the number of carbon atoms in the intermediate polymethylene linkage) has an integer value of 2 to 6, and R and R" are alkyl groups each containing '1 to 6 carbon atoms. In a fluorocarbon chain structure two carbon atoms may be linked together by an oxygen atom, or three carbon atoms may be linked together by a nitrogen atom, since oxygen and nitrogen provide very stable linkages between fluorocarbon groups and do not interfere with the highly stable and inert character of the complete fluorocarbon structure (as is shown, for instance, in U. '8. Patents Nos. 2,500,388 and 2,616,927). A saturated fluorocarbon chain containing such oxygen or nitrogen linking atom is equivalent to a perfluoroalkyl chain.
As is evident from the above formula, the complete molecule has a fluorocarbon tail at one end and a tertiary amine group at the other end, the tertiary nitrogen atom being joined to :the fluorocarbon tail by an interposed sulfonamidopolymethylene linkage.
It has been discovered that these substituted sulfonamido compounds can be readily prepared by reacting perfluoroalkanesulfonyl fluoride compounds:
with dialkylaminop olymethyleneamine compounds H2N [0 Ha) m-N The stable and inert fluorocarbon tail is repellent not only to water but to oils and hydrocarbons and imparts to our compounds unique surface active and surface treatment properties not possessed by corresponding compounds having a hydrocarbon tail. The polymethylene chain provides a stable linkage between the terminal tertiary nitrogen atom and the nitrogen atom of the amido group, and also serves to impart solubility in oils The terminal dialkyl amino group renders the molecule oil-soluble at this end. Thus the molecule is sufliciently oil-soluble, and is oleophobic at one end ice and oleophilic at the other end. It is repellent to water, oils and waxes at the fluorocarbon end and yet is soluble in oils and waxes at the tertiary amine end. These amine compounds are relatively insoluble in water.
This makes possible water-insoluble molecules that can be dissolved in oils and waxes and yet will concentrate at the surface to form an oriented surface layer having the fluorocarbon tails pointing outwardly and the opposite ends of the molecules pointed inwardly and dissolved in the oil or wax mass. A surface film results that is both water and oil repellent, and which greatly reduces the surface tension.
The solubility of the present amine compounds in oils and waxes decreases with increase in length of the fluorocarbon tail and water-insolubility is enhanced. In contrast, the corresponding compounds of conventional organic chemistry having a sulfonyl-bonded hydrocarbon tail decrease as to water solubility but incerase as to oil solubility with increase in length of this chain, Increase in length of the alkyl groups that are bonded to the terminal tertiary nitrogen atom, and increase in the length of the intermediate polymethylene chain, serves to further decrease solubility in water but increase solubility in oils and waxes. Thus the properties can be varied to best serve a desired particular use.
These tertiary amine compounds can be readily quaternized to the corresponding quaternary ammonium compounds (as by using a hydrocarbon halide or a sulfate ester as the quaternizing agent), which provide powerful surface active agents not only for oils, waxes, etc., but also for aqueous systems. Quaterniza-tion renders the compounds much more soluble in water and surface active in aqueous systems, but does not destroy utility as surface active agents in oils and waxes.
The quaternization reaction and the quaternary ammonium product compounds can be represented as follows:
R [n somnqcnswn n A- where RA is the quaternizing agent (e. g., methyl iodide, benzyl chloride or dimethyl sulfate), R is the hydrocarbon group thereof (e. g., an alkyl or benzyl group) that is covalently bonded to the quaternary nitrogen atom of the product molecule, and A is the anion of the quaternizing agent that becomes eleotrostatically bonded to the quaternary nitrogen atom. The hydrocarbon R group contains 1 to 18 carbon atoms and is an alkyl, alkylcycloalkyl, or alkaryl group, and hence in any such case it is bonded to the nitrogen atom by an alkyl carbon atom.
For convenience the generic formula of the quaternary ammonium compounds can be written as follows:
In this type of compound, the ionic terminal structure can be represented as follows:
ltipmvides an organic cationogenic group united to the polymethylene linkage and contains a quaternary nitrogen atom covalently bonded to four acyclic hydrogenated carbon atoms and electrostatically bonded to an anion. I-t:-.is:-this: cationogenic group thatrcauses therorganimchain tobe=a cationgthaving a'positive charge at thetquaternary nitrogel1;=:p0sition. -When -the compound is.dissolved in water or other suitable ionizing solvent,'the ionizedrmolecules ,-provide surface-active free-.:cations which have a terminal Efluorocarbontail-that is both hydrophobic and oleophobic. :These compounds provide cations that can plate out from solutions to :form tightly adsorbed-polar surface on hydrophilic --or.- electronegative type surfaces, -such-as; glass, lithic materials, metals zpapen-xtextiles, ,etc.,:.with the fluorocarbon tails voriente drou-twards to provide a nonpolar fluorocarbon outer surface.
EFI'hese fluorocarbon-type tertiary amine compounds and quaternary ammoniumiderivatives providesurface active agents thatare highly effective as additives for oils and waxes. reduction canzbe achieved .at concentrations of 0.1% by weight andless in animal, vegetable and mineral oils and waxes, 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. The corresponding non-fluorina-ted compounds of conventional organic chemistry do not have any .significant surface .tension reduction efiec-tin'oils and'waxes. These compounds have utility'as emulsifying agents for fluorocarbons and oils (the agent, collecting at :theinterfaces .With thefluOIocarbon tails dissolved in-thefluorocarbon phase and the; opposite ends of themoleculesdissolved in the oil phase).
The quaternary ammonium compounds provide surface active agents that are also-highly eifectiveinwatenand in neutrah-acidic and basic aqueous solutions-servingrto greatly reduce the surface tension even when'present in minute concentrations. The fluorocarbontailvprovides a hydrophobic chain that can beeven more effective in,
aqueous solutions than is a much longer hydrocarbon chain such as is employed in corresponding compounds of conventional organic chemistry, The molecules concentrate at the surface to form an oriented surface layer having the fluorocarbon tails pointing outwardly, the quaternary nitrogen ends being dissolved in the water andpointing inwardly.
"Preparation of sulfonyl fluoride starting compounds As previously 1 mentioned, our substituted sulfonamido amines can be readilyprepared by employingiperfluoroalkanesulfonyl fluorides as reactants to:supplyrtthezfluoro- 'carbon-sulfonyl iportion-of the-product molecule. wThese perfluorin'ated istarting compounds have thezformula:
Where n" has an integer value'of 5 to 12. They canbe prepared in good yields bythe electrochemical fluorination of corresponding alkanesulfonyl fluoride" and chloride compounds, serving to replace the hydrogen atoms byfiuorine atoms and, when 's'ulfonyl chloride compounds are employed, serving also to replace the chlorine atoms so as to obtain .a sulfonyl fluoridezproduct.
According to this procedure, a mixture of liquidhydrogen fluoride and the alkanesulfonylfiuor'ide or chloride is electrolyzed in a nickel-anode cellaata cell voltage of approximately 4 .to 6 volts. '.'The=.saturated perfluorina ted sulfonyl.fluoridepnoductis ;insoluble in liquid HF and wil1.-.either :"evolve' in2admixture with the hydrogen and otherzc'ellgases ortwill settletobthe bottom of wthe.cell inadmixture with other products, depending on the volatility of the particular compound and the operating conditions. It can be recovered 'from the mixture by fractional distillation. This process and the perfluorinated sulfonyl fluoride'products are described in A substantial-degree of surface tension more detail and are claimed in the copending application of T. I. Brice and P. W. Trott, S. N. 334,083, filed January 29, 1953 and since issued as Patent No. 2,732,398 on January 24, 1956. The equipment and operating procedures used in the electrochemical process have been described in the US. patent to J. H. Sim-ons, No. 2,519,983 (August 22, '1950), and in a paper by E. A. "Kauck and A. R. Diesslin published' 'by the American Chemical Society in Industrial and "Engineering Chemistry, vol. =43,-pp. 23324384 (October 1951-).
The following table lists the approximate boilingzpioints (at 740 mm.) of illustrative perfluoroalkanesulfonyl fluorides which can be employed as reactants'for making our compounds:
Compounds: B. P. C.) OF3(CF2)4SO2F CF3(CF2)5SO2F 1'15 CF3(CF2)7SO2F 154 CE; (CF2)9SO2'F .19 0 OF3(C=F2)11SO2F 222 These perfluorinated sulfonyl fluorides .are waiterinsoluble, relatively unreactive, and are highly stablewto hydrolysis in neutral and acidic. aqueous solutions. They have a high degree of thermal stability. They. are soluble in oxy-genatedorganicsolvents.
Example The following experimental description serves. to= illustrate procedures 'for making our compoundspusing the preparation of uct w-as a 7 white crystalline material. having a im'eltiug point of 113.5-'116 C., andwas identifiedas relatively pure CFs'( C1 2) 7SO2'NHC2H4N(C2H5) 2 which may be termed N-.(beta-diethylaminoethyl) pei'fluoroootanesulfonamide. Analysis showed"28.1% C (28.1% calc.) and 4.70% N (4.68% calc.).
"This amine compound was relatively insoluble in water and was ineifective as an agent for materially reducing the surface tension of Water. "However, it had pronounced surface activity in hydrocarbon media, reducing the surface tension of a refined petroleumilubricating oil from a value 'of 30.6 dynes/cm. at"25"C. to"22'5 dynes/cm. at a concentration:of:0.l%.
This. compound was quaternized by reacting 3 ,;,.grams (0.005 mole) with 1.26 grams (0.01 mole) of dimthyl sulfate. The reaction is exothermic and was completed in a few minutes, producing the'desired quaternary ammonium salt:
and was then .dissolved in ml. water. "This solution wastested asa surface active additive and Was'iound' to .-ha-ve..a high degree of activity both in water and oil.
@It .was..found. that this quaternary ammonium comthe quaternary ammonium salt). The extreme activity was further shown by the fact that the surface tension was reduced to 17.5 dynes/cm. at a concentration of only 0.001%, and it was reduced to 48 dynes/cm. at the extremely minute concentration of 1 p. p. m. (0.000l% The surface tension of a refined petroleum lubricating oil was reduced from 30.6 dynes/cm. at 25 C. to 24.5 dynes/cm. at a concentration of 0.1%.
A further sample of the amine compound was quaternized with methyl iodide by dissolving 4 grams of the amine compound in 50 ml of ether, adding 1.5 ml. of methyl iodide, and refluxing for 48 hours. The reaction mixture was filtered and 1.3 grams of solid product was obtained, comprising in crude form the desired quaternary ammonium salt:
This salt product was dissolved in 100 ml. of water and tested for surface activity.
It was found that this particular compound was too insoluble in oil to be usefully effective. However, it was highly active in water, reducing the surface tension of pure water at 25 C. to a value of 17 dynes/cm. at a quaternary salt concentration of 0.01% and to 21.5 dynes/cm. at a concentration of 0.001%.
1. The new and useful fluorocarbon compounds of the class consisting of the perfluoroalkane-sulfonamidopolymethylcne-dialkylamine compounds represented by the formula:
where R; is a perfluoroalkyl chain containing 5 to 12 carbon atoms, m has an integer value of 2 to 6, and R and R" are alkyl groups each containing 1 to 6 carbon atoms; and the corresponding quaternary ammonium compounds represented by the formula:
where R is a hydrocarbon group containing 1 to 18 carbon atoms which is bonded to the nitrogen atom by an alkyl carbon atom, and A is an anion.
2. The new and useful quaternary ammonium compounds which are represented by the formula:
References Cited in the file of this patent UNITED STATES PATENTS 2,403,207 Barrick July 2, 1946