US 2764603 A
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United States Patent ice 1 2,764,603 AIZKYLAMINOA'IZKYL-PERFLUOROAMDES' Arthur H. .Ahlbrecht; White Bear Township, Ramsey County, Minn., assignor toMinnesota Mining Air ManufacturIng Company, St. Paul, Minn., a corporation of Delaware No nrawii g. Application'Api'il'21,'154,
' SerialNo. 424,789
lplaim. (c1. also-404.5
This invention relates to my discovery of a new and useful'class of reactive fluorocarbon'compoun'ds. These compounds have utility as surface active agents, as starting compounds for making derivatives, and for other purposes;
These novel compounds are perfluoroalkyl dialkyl amine compot'inds'uniquely characterized as to structure. by having in the molecule a terminal carbonyl b'onded perfluoroalkyl chain which provides a nonpolar saturated fluorocarbonftail that is both' hydrophobic and 01ccphobic. Thesecompounds may be termed perfluoroa lkyl amidopolymethyl-ene-dialkylamine I compounds and are represented by the generic formula:
Cn 2n+1C ONE-(CH2) mN R! I and bythe'equivalent formula-for compounds containing a normal p'e'rflu'oroalkyl chainz 0 H R no r)'"-ii-'N-' oni);nn
RI! whereri (the number of carbon atoms inlthe' terminal straight-chain orb ranched-chain perfluoroal kyl tail) has an integer value of 3 to 11 rh (the number of carbon atoms in the intermediatepolymethylene linkage) has an integer valueof 2 to 6, and R and'R ar'e a'lk'yl groups each containing 1 to 6 carbon atoms.
As is evident from the above: structural formulas-the complete molecule has a perfluoroalkyl .tail at one end and a' tertiary. amine group at the other end,"'. the-ftertiai'y nitrogen atom being. joined tothe fluorocarbon tail by an interposed amidopolymethylene linkage.
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 carbonylabonded 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 enhance solubility in oils and waxes. The terminal dialkyl amino group renders the molecule oilsoluble at this end. Thus the molecule is sufiiciently oilsoluble, and is oleophobic at one end 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 compounds are relatively insoluble in Water (even the lowest members of the series having a solubility in water of less than about 1% by weight at room temperature).
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 out- Patented Sept. 25, 1956 p 2 Wardly nonpolar and is both water and'oil repellent, and which greatly reduces the surface tension;
The solubility of the present compounds in oils and.
waxes decreases with increase in lengthof the fliior'o'car bon tail, andWa-ter-insolubility is enhanced. In contrast, the corresponding compounds of conventional organic chemistry having a carbonyl-bonded hydrocarbon tall decrease as to water solubility but increase as to oil solubility with increase in length of this chain. In; crease in length of the alkyl groups that are bonded to the terminal nitrogen atom, and increase in length of the intermediate polymethylene chain, serve to further defluorocarbon tail containing-at least three carbon'at-orns' and the preferred number is 5 to 11. It is also of critical importance that this fluorocarbon chain be free from hydrogenatoms. In particular, thepresence of even one hydrogen: atom onthe la'st'or next to last carbon atom of thel' fltail will markedly alter the surface active and solubility properties, reducing surface activity andthe by drophobic andoleophobiccharacteristics ofs'urface coat ings. Hydrogen is electropositive. whereas fluorine is stronglyelectronegative; hence th e presence of hydrogen and fluorine in the terminal portion of the'ltail renders it polar instead of nonpolar; and also renders the tail less s'table to heatingowing to the opportunity of 15:
hydrofluorination, and provides opportunity for chemical attack.
Thesefiuorocarbon-type tertiary amine compounds pro' vide surface active agents that are'highly effective a-s'ad ditivesfor oils and waxes. A remarkable degree ofsur face" tension' reduction can be achieved at coiiciitra tions'of 0. 1%' by Weight and less inanimaL'vegetable and'gnineraloils and waxesj ihc'luding petroleum solvent'sjgasoline, kerosene,'fuel' oils, lubricating oils, and para flin' waxes thereby, for instance} improving such properties as surface protection, flow, spreading, penetration, and atomization or sprayability. V, The corresponding non-fludrinated compounds of conventional org'a'nic chemistry do not have any significant surface tension'redu'c'tion effectin oils andwa'xes. M h I I .These compounds have utility as emulsifying agents for fluorbcarbonsand oils (the age'nt'collec'ting at'the interfaces'with the fluorocarbon tails dissolvedinl the fluorocarbon phase and the opposite ends of the'm'olecules dis solvedin the oil phase). I V
The present compounds also'have particularly noteworthy value in serving asstartingcdmp'ounds for Ina-king the corresponding quaternary ammonium compounds, which can be readily prepared by using a hydrocarbon halide or sulfate quaternizing agent:
where RA is the quaternizing agent (e. g., methyl iodide 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, and A is the anion of the quaternizing agent that is electrostatically bonded to the quaternary nitrogen atom. These fluoro-' carbon quaternary ammonium compounds are unusually efiective surface active agents both in water and aqueous solutions and in oils and Waxes. Quaternization renders the compounds much more soluble in water and surface active in a queous systems, butdoes not destroy utility as surface active agents in oils and Waxes. Thesequaternary derivatives are 'describ'ecli in more detail and are claimed in my Companion application filed of evenpdate I herewith, SJN. 424,788.
' A feature of the present compounds is that l they can be readily prepared, by reaction of thealk yl'esters of The s fassfi a iea ra uatvrma refines? m nera s lat. 25 C.,was reduced from 31 dynes/cm.to v18 dynes/cm.
at a concentration of 0.1% J by weight. The value for a refined paratfin wax, in a fluid melted stateat 100 0., was reduced from 24 dynes/cm. to 18 dynes/cm. at a concentration of 0.1%; and that of a rnicrocrystalline paraflin wax, also measured; at 100" .C., .was. reduced from275 perfluoroalkyl monocarboxylic acids (conveniently the Q ethyl esters) with dialkylaminopolymethyleneamine compounds, as shown by the following equation:
The perfluoro ester starting compounds are disclosed in the U. S. patent of Diesslin, Kauck and Simons, No. 2,567,011 (Sept.-4, 1951).
Example This example illustrates'the preparation of the present compounds by a procedure of general utility, makin it dynes/cin. to 24 dynes/cm. at a concentration"of 0.1%;.
This. compound in minute. proportion materially inhibits the evaporation of volatile hydrocarbonssuch as gasoline, owing to formation of a surface barrier The following table lists other illustrative compounds that have been similarly prepared and gives the measunnecessary to individually describe similar experiments by which other compounds have been made.
- A 1000 ml. ,1necked flask was charged with 426' grams (0.965 mole) of ethyl perfluorocaprylate, CIF15C'OO'VC2H5, and 2 ml. of absolute diethyle ther as solvent. The flask was cooled in anice bath and 98.2
. grams (0365 mole) of dimethylaminopropylenearnine, H2NCsHeN(CHs)z, was added slowly enough tomain tain a temperature below 35 C. in the cooled reaction flask. p The flask was then removed from the ice bath and allowed to warm-to room temperature. ,It was placed under a 5 plate column forvacuum distillation. As the pressure was reduced, the ether distilled off, leaving the amine reaction product, which was distilled off at about mm. pressure'at the boiling range of 154-158 C. A
total of 440 grams (0.882 mole) was obtained (yield of 91.5%). The product was identified as relatively pure: C7F15CONHC3HN(CH3)2 Analysis showed 5.68% nitrogen (5.61% calc.). The boiling point was 155 C. at 18 mm. pressure. The reinactive index at C. was 1.3559. The product was a colorless viscous liquid having a characteristic amine odor. This compound may be designated as N,N-dimethyl-N'-perfiuoroeaprylamidopropyleneamine.
The surface activity of this compound was demonstrated by measurements showing the reduction in surface tension of mineral oils and waxes caused by the presence of minute proportions of the compound.
' ured vacuum boiling points (at the indicated pressures in millimeters) and refractive indices (at the indicated temperatures in degrees Centigrade). These compounds are allhigh 'boiling liquids at room temperature except for the last one, which is solid.,
- :The surface activity of the third compound in theabove list is illustrated by experiments on surface tension reduction wherein the value for linseed oil at 25 C.,was re- 7 duced from 32 to 19'dynes/cm. at0.1% concentration;
that for mineral oil at 25 C. from 3,1 to 19 dynes/cm.
References Cited in the file of this patent UNITED STATES PATENTS 2,567,011 Diesslin et al Sept. 4, 1951 2,589,674 Cook et a1. Mar. 18, 1952 2,593,737 Dies'slin et a1. Apr. 22, 1952 2,691,043
Husted Oct. 5, 1954