California Association of Chemtstry Teachers Clay M. Shark San Diego State College San Diego, California 9211s
Organic fluorhe Chemistry
Organic fluorine chemistry is a manmade area of chemistry that has no counterpart in nature. Most of the advances in the field have been made since 1930 with a tremendous growth in the literature since 1950. Most of the research in organic fluorine chemistry bas been done in industrial laboratories sponsored by private capital or government contracts. Only a limited number of chemists in academic institutions are familiar with or do research in this extremely important area of chemistry with which the average citizen is in daily contact. In one respect organic fluorine chemistry is similar to polymer chemistryneither subject normally finds its way into courses required to be taken by the chemistry major. The objective of this paper is to provide an introduction to organic fluorine chemistry and to arouse in the teacher of chemistry a desire to include part of this subject in his normal courses.' It is hoped that the reader will be inspired to consult some of the voluminous literature of the field and to perhaps add some of the important reference works in the field to the library a t his institution. Applications The average citizen is surrounded in his daily life by organic fluorine compounds which serve to make his life easier and more comfortable. Teflon@ coats the housewife's cookware, Freons@jQ2 permit the refrigerator to cool and serve to propel insecticides or whipped cream from spray cans, Sc~tchgard@~ protects fabrics from water and stains, and fluorinated steroids serve as anti-inflammatory drugs. I n Table 1 the above materials and others are listed in order to illustrate the impact of organic fluorine compounds on the average citizen (1-4). The wide application of organic fluorine compounds is generally due to either the unusual physical properties of these compounds or to the enhancement of some chemical property by a substituent fluorine atom or group. The reasons for these applications will become Presented at the Summer Conference of the California kssaciation of Chemistry Teachers, Asilomar, California, August 16, 1967. 'This peper is based on a. book now in preparation, "Organic Fluorine Chemistry," W. A. Sheppard and C.M. Shttrts. W. A. Benjamin, publisher, expected publication date 1968. 'Tefion@and Freon@ are registered trademarks of theE. I. du Pont de Nemours and Co., Inc. ' Scotohgard@is a registered trademark of the MinnesotaMining and Manufacturing Company.
more apparent as information is presented later in the manuscript. Fluorine, Fluoride, and the Carbon-Fluorine Bond Fluorine is well known as the most electronegative of the elements and as a consequence forms the most stable bond with carbon of any of the halogens: C F , 109 kcal; C-CI, 78; C-Br, 65; C-I, 57. Although the great reactivity of fluorine is well known, it is less
Table I.
Applications of Orgonic Fluorine Chemicals
Common name and/or formula Chemical name and/or structure -
~
-~
Application
Freon-lip, (CCLF) Refrigerant gases Freon-12@ (CCbF*) Propellants in spray cans Pronellant for food products Freon G318@ Perfluo.--, Freon 13-B-l@ Fire extinguisher agent; carBromotduoromethane ried in commeroial aircraft Teflon@ Unique thermally-stable poly.CF2CFxCF2CF2ChCF2CF, mer: excellent lubricating properties Polymer with unique elast* Viton-A@ Copolymer of H,C=CHF and meric properties, e.g., for "0" rims in extremely corroCF,CF=CF, sive envbonments Fabric mating to protect against Scotchgard@ both water and grense Contains a peduoroacrylic ester Insecticide similar to but sup* DFDT or Gif rior to DDTfor many applica1,l-Bis(p-fluorophenylb 2,2,2trichloroethane tions; is not readily detoxified by insects Extremely effective rat poison Rodenticide 1080 (FCBCOONa) Diisopropylfluorophospbate Nerve gas--extremely toxic; 0 treatment of glaucoma (CHahCH \p/ -.u--vw-v
(cH,),cH' \F Dielectric in 1000 kvA, 15 kv Ootaflnoropropane (CIFJ transformers CF~CFICF~ Tranquilieer, more effectivethan Vesprm@' 10(r-Dimethylaminoprop~l~Z its unfluorinated analog triflu~rometh~lphenothmzine
H I
Aristomrtw Antiidammatory drug, more S-a-Fluaro-16a-17-n-isoproeffective than hydrocortisone pylidenedioxy-1-hydrocortiitself sone Vesprin@-foreign trademark. AristowrtGregistered trademark of Lederle Laboratories.
Volume 45, Number 3, March 1968 / 185
well known that the reason for this great reactivity is the very low dissociation energy for molecular fluorine of only 37 kcal/mole. The problem of introducing fluorine into organic molecules can best he illustrated by comparing the thermochemistry of chlorination and fluorination. Chlorinotion of Hydrocarbons
Reaction
Step
-
hu or
Initiation
1
Propagation 2 3 Termination 4 5
6
Cll
heat
RII R. R. C1. It.
2 Cl.
Fluorinoiion of Hydrocarbons
Step
---
+ C1. R . + HC1 + CIS-RCl + Cl. + CI. RCI + Cl. CL + R . R-R
lo lb Propagation 2 3 Termination 4
5 6
AH (Keal/mole) F. 2F. +37.5 Fs+RH-R. +IiF+F. 4.1 RH F. R. HF -34.0 R. + F z - R F + F. -68.0 R. F. RF -107 to -112 F. F . + FI -37.5 R. Fragmentation
+ + +
+
+
I n chlorination the energy released in the propagation steps is less than that required for the initiation step, the breaking of the C1-C1 hond. Energy released in the termination step can be removed a t a fast enough rate to control the overall reaction. I n contrast, in fluorination there is a very low energy of initiation, particularly by step Ib, and this is much less than energy released in the propagation steps. Chain reactions can occur through further initiation by energy released in the propagation steps. To make the situation worse, the energy in termination step 4 is greater than the energy binding the carbon-carbon hond so that fragmentation of the product is likely. The problem of fluorination has been discussed by Miller, who first postulated step lb as a means of initiation (5, 6). The unfavorable thermochemistry for direct fluorination which can be controlled only with extreme difficulty has led to the development of many methods of indirect fluorination which will comprise a major portion of this paper. Fluoride ion has two important properties which greatly influence organic fluorine chemistry. The small fluoride ion (radius 1.36 A) has an unusually low polarizahility of 0.86 A3 (Cl-, 3.05; Br-, 4.17; I-, 6.28) and an extremely high heat of hydration of 123 kcal/mole (Cl-, 89; Br-, 81; I-, 72). The low polariaability is one factor which makes nucleophilic displacement of fluorine from carbon difficult and, along with the great strength of the carbon-fluorine bond, contributes to the inertness of many organic fluorine compounds. The high heat of hydration of fluoride ion contributes to the hydrolytic instability of many organic fluorine compounds and makes impossible displacement reactions with aqueous hydrofluoric acid. Compare:
+ HI., + HF.,
C2H60H C2H60H
186
/
-
CnHsI
$? C2H9
Journal o f Chemical Education
+ H?O
+ Ha0
Although the hydrolysis is theoretically possible it does not occur a t a practical temperature because of kinetic reasons. The sheath of tightly bound "unpolariaable" fluorine (C-F bond, 1.32 A) prevents attack on carhon by water molecules. Carbon tetrafluoride is exceedingly stable. Related to the fluoride ion is hydrogen fluoride which is an extremelv stable molecule with a hond enerev of ~-~ 135 kcal ( ~ 6103.2; , HBr, 87.5; HI, 71.4). -The stability of hydrogen fluoride makes it a favored product to be eliminated from a compound containing hydrogen and fluorine if a kinetic pathway is available. The carbon-fluorine bond is anomolous when compared with other "single" bonds, as shown in Table 2, which presents bonding data for fluoromethanes and chlorofluoromethanes as summarized by Patrick (7). ~
-3 -23
Reaction
Initiation
Another interesting example is the theoretical hydrolysis of carbon tetrafluoride
~
~
~
Table 2.
Bond Lengths and Energies in Fluoromethanes
Bond length CF, Com~ound
A
Bond Bond energy length C-F, C-F, kcal Compound A
Bond energy C-F, kcal
It can he seen in Table 2 that as fluorine accumulates on carbon, the carbon-fluorine bond significantly becomes shorter and stronger. This contrasts with normal bonding experience in which for a given hond type the hond length and bond strength are almost constant. Explanations for the effect have been offered originally by Brockway (S),Pauling (9),and more recently by Hine (10). These workers considered the highly ionic nature of the carbon fluorine bond, about 430jo (C-Cl, 12y0; C-Br, 2%;. C-I, OOjo), and wrote ionic resonance structures involving double bond and no-bond forms between carbon and fluorine as shown. F
F
I F+F I
F
H
Fe
I I
C=F* u 12 resonRnce forms F
For CF, there are 12 forms possible; for CHFa, 6; for CH2F2,2; and none for CHaF. The increased number of double bond resonance forms then would he expected to give bond shortening and strengthening. More recently Peters (11) has applied a molecular orbital treatment to the problem. He suggests that electron withdrawal from the p-orbitals of carbon by fluorine leads to a change in hybridization of carbon from possibly q2."in CH3F to sp2.4in CF+ The resulting increased s-character in the C-F bonds of CF, when taken with ionic attraction leads to hond shortening and bond itrengthening. I n this regard, the bond length of 1.30 A for the C-Y hond in tetrafluoroethylene, CF-CF*, where carbon is presumed to be sp2 hybridized would indicate that Peters may well have the best explanation.
Effect of Fluorine in Organic Fluorine Compounds
Perfluorinated organic compounds are thermally very stable and unusually resistant to chemical attack. Their properties have been completely reviewed (18). Partially fluorinated compounds containing hydrogen alpha to fluorine do not always have this stability because of the ease of elimination of hydrogen fluoride. Those Freon@ (fluorocbloroethanes and -methanes) which contain only fluorine and chlorine owe their usefulness as refrigerants to their low toxicity as well as physical properties which are primarily a result of their thermodynamic and kinetic stability. When bonded to carbon in saturated compounds, fluorine markedly affects neighboring groups through its powerful inductive effect. This can be illustrated in the series of fluorinated acetic acids; the following pKa's are observed: acetic acid, pKa = 4.75; fluoroacetic, 2.68; difluoroacetic, 1.48; trifluoroacetic, 0.70. Classical measurements on aromatic compounds have given substituent constants for fluorine. The inductive constant (c,) of +0.52 confirms the powerful electron withdrawing power of fluorine while the resonance constant c of -0.44 shows that fluorine donates electrons by resonance. Fluorine is almost as strong a resonance donator as a methoxy group for which c, = -0.51. Fluorine is an ortho-para director with a very powerful directivity to para substitution. Compare nitration of chlorobenzeue and fluorobenzene.
The ratio of ortho/para isomers is the reverse of what one would predict on the basis of steric effects. The powerful para-directivity is probably due to inductive effect in the sigma C-C bonds which induces a larger plus charge a t the ortho position plus a resonance effect in the pi-system which provides electrons a t the para position. The relative rate of fluorobenzene to benzene is greater (0.45) than for chlorobenzene (0.14) indicating the greater availability of electrons in the pi-system of fluorobenzene. Another example of the marked effect of fluorine is in the fluorinated olefins. Considerable evidence has accumulated that indicates a carbon-carbon double bond is significantly weakened by fluorine substitution. Ethylene cannot be thermally diierized to cyclobutanes. I n contrast tetrafluoroethylene gives octafluorocyclobutane.
ZCFFCFS
The idea that the carbon-carbon double bond is weakened by fluorine substitution is strengthened by heats of hydrobromination of a series of ethylenes (IS); CHF CH,, - 16.8 kcal/mole; F,C=CCl,, -22.05; F,C= CFCI, -26.07; CFFCF~, -32.99. A difference of 16.1 kcal/mole exists between ethylene and tetrafluoroethylene which may be attributed to a weakened double bond, presumably less pi-orbital overlap. Stated another way, fluoroolefins exhibit greater diradical character than normal olefins. I t has been repeatedly shown that fluoroolefins react more readily with radicals as illustrated by their ready polymerization with radical initiators. Typically fluoroolefins react sluggishly with electrophilic reagents as compared with hydrocarbon olefins. Again a reduced electron density in the pi-system will explain the observations. Thermodynamic calculations by O'Neal also confirm that the carbon-carbon double bond of tetrafluoroethylene is weaker (14). Anionic reagents readily attack fluoroolefins at the most fluorinated vinyl carbon, the carbon with the most positive charge. This permits fluoroolefins to add alcohols and amines to the double bond, a reaction uncommon to hydrocarbon olefins (15). Step 1
1-BuOe
Step 2 t-BuOCFLX&e
--
+ CFFCC~ + 1-BuOH
t-BuOCFtCClze
+
tBuOCFzCClzH GBuOe
An even more exciting reversal of chemistry is found in the reactions of perfluoroaromatic compounds. Reactions of benzene are usually with electrophilic reagents. I n contrast perfluorobenzene reacts preferentially with nucleophilic reagents.
Only a few examples have been cited in this section of the way in which fluorine substitution effects the chemistry of organic compounds. Many other effects occur. The examples must be considered as only illustrative. Space limitations preclude further discussion of chemical effects or an attempt to discuss biological effects. Classical Methods of Fluorination
Prior to 1955 enormous numbers of organic fluorine compounds were synthesized by what Sheppard and Sharts (16) classify as classical methods of fluorination. Many of these methods are still useful but many have been supplanted by recently developed methods. Fluorine and Halogen Fluorides
Flourine has been used directly for addition to carbon-carbon double bonds and for substitution of hydrogen in selected fluorine compounds. Use of fluorine for these reactions cannot be considered a useful general method. Fluorination by fluorine is unlikely to be used in normal organic syntheses. Some examples from the very limited literature are:
200°, autoclave
r a d i ~ a linhibitor
Fz' n F zK> w % Volume 45, Number 3, March 1968
/
187
F
F
F F I I F-C-C-F
% % !
F F F F
I I I l I I I I
+
F-C-C-C+-F
cl CI
(*.a)
Cl Cl Cl Cl
Halogen fluorides did not find extended use classically and their wider use has been developed more recently. The earliest synthesis of hexafluorohenzene was achieved using bromine trifluoride to fluorinate hexachlorobenzene (19).
-
CrCls
BrFa
oomplex mixture contzining C a n
0-150°
Hydrogen Fluoride.
+ HF
No Catalyst
-78 to 0"
cyclohexyl fluoride(80%) (80)
HF. THF. CH~CLI
5-pregnen-3~-01-2Oae
-80 to -50D, 6 hr
,
Sduoropregnan-3Wl-20-one
CHFCCL
+ HF ----- CHzCClzF(50%)
(CHs)d2=CH.
(21)
3 hr
65'.
HF
CBrCLCHd3r
HF. Sb(V) 160". autaolava
CFaCHzBr(85%)
(27)
(19)
The most important and most widely used fluorinating agent is hydrogen fluoride, frequently with a catalyst present. In this section only uncatalyzed additions and substitutions are considered. Anhydrous hydrogen fluoride will add to alkenes and acetylenes a t low temperatures to give products as illustrated below. However, temperature must be controlled very carefully. As a strong Lewis acid hydrogen fluoride initiates cationic polymerization so that highly substituted alkenes undergo polymerization. The hydrogen flouride-catalyzed alkylation of isobutylene with isobutane was a vital process for synthesis of aviation fuel in World War 11. cyclohexene
tution reactions. Hydrogen fluoride in the presence of antimony salts is the most important industrial fluorinating agent and is used to manufacture chlorofluoromethanes and -ethaues.
(22)
A number of rules for determining which halogens will be substituted have been developed and an extensive review published (29). Oxidizing Metallic Fluorides
Cobalt(II1) fluoride is the most important oxidizing metallic fluoride. Its use was developed for the Manhattan District to obtain perfluorocarbons and in recent years it has been used to form intermediates for synthesis of perfluoroaromatic compounds. During fluorination it is reduced to cobalt(I1) fluoride which can be reoxidized with fluorine to the parent cobalt(II1) fluoride. Silver(I1) fluoride is similar in action but more convenient for laboratory use; it is not convenient for use in a cyclic process. Lead tetrafluoride, which will be discussed later, can add fluorine smoothly to carhon-carbon double bonds. Other oxidizing fluorides such as MnFa, CeF,, BiF,, and UFs have not found extensive use. CoFrsuooeasive fluorinations
n-C7Hx
-k -
176200. 275300, 300CoFl
p-xylene
Polymer
p-CFa-CsFlo-CFa(42%)
to 350"
0-25O
n-C1Fd79%)
500-
(30) (90-31)
p-CFa-CsF4--CF3
250-330'
naphthalene
perfluorodecalin, C~oFd56%) (32)
The use of oxidizing metallic fluorides for fluorination has recently been reviewed with an accompanying detailed interpretive discussion (33). Group I and I1 Fluorides
Hydrogen fluoride is a mild reagent for effecting substitution of some kinds of halogen by fluorine. Halogens activated by an aromatic ring are particularly labile. Unactivated halogens cannot be conveniently substituted without a catalyst.
HF, 1-2 hr
4-C1-C6HcCC4 -----+ 4-CI-CeHrCFd83%) l l o O , 14 atm Hydrogen Fluoride.
(86)
Antimony Fluoride Catalysts
Antimony(II1) fluoride is a mild fluorinating agent and antimony(V) fluoride a powerful one for substitub ing chlorine or other halogen by fluorine. Equally satisfactory and significantly cheaper is use of a mixture of antimony(II1) and (V) chlorides with hydrogen fluoride. With this combination a wide range of chlorinated coumpounds can be fluorinated by substi188
/
Potassium fluoride and silver(1) fluoride are the most important fluorinating agents in this class. They act by substituting fluorine for halogen or oxygen functions. Recent advances in the use of potassium fluoride in polar solvents have been made. The discussion of potassium fluoride will be deferred to the section "Modern Methods." Classically silver fluoride and mercury(I1) fluorides were the major reagents for replacing a single isolated halogen. Silver fluoride still finds occasional use.
Journal of Chemical Education
Shiemann Readion
The Shiemann reaction is the most important method for introducing fluorine into aromatic compounds.
cesium fluoride-catalyzed addition of fluorine to the carbonyl group of perfluoroketones (46). 0
1. HCI, NaNO, OD 2. NaBF.,OD
CF,&CF,
F,. CBF -7S0
OF
I
CFGFCH,
(90%)
(48)
Another technique discovered by Grakauskas is aqueous fluorination of urea and similar carhonyl derivatives (47). Only one example is shown above, but the brevity of the presentation here should not detract from the importance of this method of fluorination. The reaction has been reviewed extensively in several sources (36-38). Electrochemical Fluorination
This is a useful method discovered by Simons that has been exploited primarily by industrial rmearch workers. It is not generally useful to the practicing organic chemist. It has been reviewed thoroughly and the reader is referred to these reviews (39-40). An example of this reaction is illustrated below: n n S F , 0/CHaCHzCHIC
\electric
current
CFaCFdXC
F
(36%)
The technique has been extended by Sharts to a number of alkylamines. Hypofluorous acid seems a probable intermediate in aqueous fluorination.
Studies by Stevens have shown bromine triflnoride to be a controllable reagent (49). 0
(41)
\F
Additional discoveries for taming fluorine and halogen fluorides should be anticipated.
Jet Fluorinotion
This is a specialized technique developed by Bigelow for use of impinging streams of fluorine and gaseous organic compounds. Many novel compounds have been synthesized by the method but complex mixtures of products are usually formed. For example, from fluorination of succinonitrile is obtained carbon tetrafluoride, nitrogen tritluoride, perfluoroethane, perfluoromethylamine (CF3NF2), perfluoropropane, perfluorodimethylamine, perlluorobutane, N-trifluoromethylperfluoropropylidine imine, perfluoropyrollidine, perfluoromethylpropylamine, and pedluoro-n-butylamine (4%). Reviews on jet fluorination are available (43-44). Modern Methods of Fluorinotion Fluorine, Halogen Fluorides, and Aqueous Fluorinotion
In recent years fluorine and halogen fluorides have been partially tamed primarily by use of low temperatures and careful control of conditions. Merritt and Stevens achieved remarkably controlled addition of fluorine to a series of unsaturated compounds a t -78' in an inert solvent (46).
Improved Fluorinating Agents
In recent yeam a number of novel new fluorinating agents were invented and applied to synthesis of organic compounds. The more important of these are sulfur tetrafluoride (SF4), perchloryl fluoride (FClOa), lead(1V) fluoride formed in situ, and the equivalent of bromine fluoride (BrF) and iodine fluoride (IF) formed in situ. New applications have been made of older reagents such as hydrogen fluoride and silver difluoride. Of the new reagents sulfur tetrafluoride is certainly the most useful. It is selective and can accomplish reactions never possible previously. Its greatest utility is in converting oxygen functions into fluorinated groups. For an excellent review of the reactions of sulfur tetrafluoride the review of Smith should be consulted (60). Some examples given in the review and an earlier reference (61) are presented here. 0
SF,, l l O D
CHI&CHs
HOOC-CIC-COOH F,, CCI,F, -78" 4A Molecular Siwe
trans-
"F
Recently Lnstig, Pitochelli and Ruff reported the
16 hr
CHd2F,CHa(64yo)
SF.,
1700
FF3C-C=C-CF3
(80%)
A milder reagent than sulfur tetrafluoride is phenylsulfur trifluoride prepared by silver(I1) fluoride oxidation of diphenyl disulfide (6%). Perchloryl fluoride is a valuable reagent for replacing Volume 45, Number 3, March 1968
/
189
active hydrogens by fluorine. It is a potentially hazardous reagent and may explode with some organic compounds.
the use of polar solvents as fluorination media. The availability of dimethyl sulfone, tetramethylene sulfone, N-methylpyrrolidone, glyme and diglyme, dimethylformamide, glycol and similar solvents has made potassium fluoride a fluorinating agent of choice for displacing halogen or oxygen functions. The probable reason for the success of these solvents is that they provide a kinetically significant amount of fluoride in solution. Because of cost and availability potassium fluoride is usually used although cesium fluoride appears to be significantly better. Examples which follow illustrate the reaction.
Lead(1V) fluoride is difficult to prepare in a pure dry state. An alternative use has been to prepare it in situ from lead tetracetate and hydrogen fluoride. This is a very useful reagent for adding fluorine to a double bond.
Ad)
&
Pb(OAC)4, HF CHCI,, -75: 15 min*
I n very recent work with aromatic systems very high temperatures have been used and the solvent omitted. The method has been used to synthesize hexafluorobenzene from hexachlorobenzene (64).
Addition of Fluorinofed Units
Addition of the elements of bromine fluoride or iodme fluoride can be accomplished by using a source of bromonium or iodonium ion in liquid hydrogen fluoride. The method has been extensively employed by Bowers in steroid research (67). N-Bromosuccinimide or -acetamide and N-iodosuccinimide are usually used as the sources of bromonium or iodonium ions.
This extremely important method for synthesizing fluorinated compounds will be reviewed in a publication now in preparation (16). The topic is too extensive for broad coverage here. Briefly, perfluoroalkyl radicals are available from a number of sources and can undergo the reactions typical of radicals.
Carbanions derived from unconventional or conventional sources also play an important part in synthesis. An important use of hydrogen fluoride in recent years has been addition to epoxides. As a means of introducing fluorine into steroids this reaction has been widely used. For example, a series of 9B-llpepoxypregnene derivatives were converted into the correspondingSol-fluoro-116-hydroxypregnenes on treatment with anhydrous hydrogen fluoride in tetrahydrofuran a t -60' (58-69). Trans-addition of hydrogen fluoride occurs. Alkali Holides in Polor Solvents
Probably the single most important advance in what can be considered a classical method of fluorination is
+
-
CFsCF=CF3 FCF',CFWF, (from CsF)
cF,$cF, --------. triethylene ~IYODI
Difluorocarbene, generated in the usual ways (69), has been widely used to synthesize geminal difluorocyclopropanes and other compounds. An elegant example discovered by Mahler is addition of perfluoro-2-butyne (7'3).
Heteroatom fluorine-containing groups can frequently be used to introduce a heteroatom-fluorinated group into an organic molecule. The radical additions of groups such as CFS-C1 (71), SF&I (78-74) and NFrNF2 (76-76) have been extensively investigated.
Literalure of Fluorine Chemistry
The chemist who desires to enter the field of organic fluorine chemistry will find the primary literature a jungle in which he can see only bushes and trees. The secondary literature of published books provides a more efficient and more gentle way to involvement. The volumes listed below are suggested as initial sources to study or become familiar: "Houben-Weyl, Methoden der Organkchen Chemie," Volume V, Part 3, edited by Eugene Miller (Georg Tbieme Verlag, S t u t t gart, 1962). "Fluorine Chemistry," Volumes 1 5 , edited by J. H. Simons (Academic Press, New York, 1950,1954, 1963,1965,1964). "Advances in Fluorine Chemistry," Volumes 1-5, edited by M. Stacey, J. C. Tatlow and A. G. Sharpe (Butternorth, Washington, 1960, 1961, 1963, 1965, 1965). "Organic Fluorine Chemistry," M. Hudlicky (The Macmillan Co., NewYork, 1962). "Aliphatic Fluorine Compounds," A. M. Lovelace, D. A. Ransch and W. Postelnek (ReinholdPuhlishing Corp., New York, I(IEP\ L""YI.
"Aromatic Fluorine Compounds," A. E. Pavlath and A. L. Leffler (ReinholdPublishine Corn.. 1962). 'r~oxicAliphatic Fluorine Comprhnds," F. L. M. Pattiion (Elsevier, London, 1959). "Some Aspects of the Chemistry and Toxic Action of Organic Compounds Containing Phosphorus and Fluorine," B. C. Sanders (Cambridge University Press, New York, 1957). "Organic Fluorine Chemistry," W. A. Sheppard and C. M. Shart,s (W. A. Benjamin, Inc., New York, in preparation).
- . , ~ ~
Literature Cited BRYCE,H. G., "Fluorine Chemistry," Vol. 5 (Editw: J. H.) Academic Press, Inc., New York and LonSIMONS, don, 1964, pp. 295498. J. M., JR.,"Advances in Fluorine Chemistry," HAMILTON, J. C., AND SHARPE, Vol. 3, (Editors: STACEY, M., TATLOW, A. G.) Butterworth, Washington, 1963, pp. 117-180. DORMAN, C., GRAY,D. N., AND HERR,F., "Aromatic Fluorine Chemistry," PAVLATH, A. E., AND LEFFLER,A. L., A.C.S. Monograph 155, Reinhold Publishing Corp., New York, 1962, pp. 669-691. H~DLICKY, M., "Chemistry of Organic Fluorine Compounds," Chapter X, The Macmillm Co., New York, 1962, pp. 332-357.
(5) MILLER,W. T., JR..KOCII,S. D., JR.,AND MCLAPPERTY, F. W., J. Am. Chem. Soc., 78,4992 (1956). (6) MILLER.W. T.. AND KOCH,S. D., JR., J. Am. Chem. Soc., 79, 3084 (19571. (7) P A ~ C = , C. R., "Advances in Fluorine Chemistry," Vol. 2, 1061. 1 -Rnttprrmnrth -..-- - .. - - .-, -. - -,rn. -. (8) BROCKWAY, L. O., J. 1'hys. Chem., 41,185,747 (1937). (9) PAULINO, L., "The Nature of the Chemical Bond," 3rd ed., Cornell University Press, Ithaca. New York. 1960,. DD. .. 314315. (10) HINE,J., J. Am. Chem. Sac., 85,3239(1963). (11) PETERS,D., J. Chem. Phys., 38,561 (1963). (12) REED,T. M., 'Tluorine Chemistry," edited by Simons, Volume V, Academic Press, New York, 1964, p. 133. J. R., LEA. K.. WALDEN,C., OLSON,G. C., AND (13) LACHER, PARK,J. D., J. Am. Chem. Sac., 72,3231 (1950). (14) O'NEAL,H. E., San Diego State College, private comunicatlon. (15) CHAMBERS, R. D., AND MOBRS,R. H., "Advances in Fluorine Chemistrv." Volume. 4. Chmt. 3. (Edilors: STAGEY. M., TATLOW,"J. C., AN' &A&, A'G.) ~utterswcrth; Washington, 1965. C. M., "0rganic.Fluorine (16) SHEPPARD, W. A,, AND SHART~, Chemistry," W. A. Benjamin, Inc., New York, 1968, in (17) BOCKENMOLLER, W., Ann., 506,20 (1933). (18) MILLER,W. T., JE.,STOFFER,J. O., FULLER,G., AND CUERIE. A. C.. J. Am. Chem. Soc.. 86.51 (1964). v.; AND I;IGGE&, W. B., Ind. (19) MCBEE, E.'T., LINDGREN, and Eng. Chem., 39,378 (1947). (20) GROSSE,A. V., AND LINN, C. B., J. 0rg. Chem., 3, 26
,-"--,. ITORA\ ,-""-,. (14RS\
(21) BOWERS,A., U. S. Pat. 3,071,602; Chem. Ahstr., 4434d (22) HENNE,A. L., AND PLUEDDEMAN, E. P., J. Am. C h m . Sac., 65,1271 (1943). E. P.. J . Am. Chem. Soc.. (231 HENNE.A. L.. AND PLUEDDEMAN. ~
(24)
~
~ ~ - - - , ~
B., AND WHALLEY,W. B., Brit. Pat. 576,189 (1946); Chem. Abstr., 42,1603d (1948). (25) Brit. Pat. 765,527 (1955); Chem. Ahstr., 51, 14823f (1957). (26) BOOTH,H. S., AND BIXBY,E. M., I d . Eng. Chem., 24, 637 BRO&J.
11019\
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