NOTES
March 20, 1953
polarization effect. It was found that an electrode either anodically or cathodically polarized in this fashion remained in its same condition after several hours of standing in 1 M sulfuric acid and was not changed even by several minutes in hot concentrated nitric acid. By “remaining in its same condition” is meant that the electrode would exhibit the same behavior in a subsequent electrolysis, which was the only criterion we could apply as to the state of the surface of the electrode. Figure 1shows the subsequent effect in an arsenic oxidation of prior hydrogen and oxygen pre-polarization treatment of the platinum anode. Figure 2 shows similar behavior in an iron oxidation. It was further observed (Fig. 3) that if an oxygen pre-polarized electrode was allowed to stand for one hour in the arsenic solution before beginning the electrolysis the electrode slowly reverted t o a condition similar to that of a hydrogen pre-polarized electrode. The most likely explanation is that the arsenic(II1) reduces the platinum oxide (probably (PtO) and gives a clean platinum surface. A similar process occurs if the electrode stands in the iron solution before the electrolysis is begun but the reaction is quite rapid, about 10 to 20 seconds sufficing for the complete removal of the oxide. The speed of this reaction probably accounts for this effect not having been observed before in iron oxida-
0 0
1
NO .ST&NDING.
I 2 3 4 ELECTROLYSIS TIME IN MINUTES.
1477
tions. However, it should be noted that, as Fig. 2 indicates, if the potential is applied and maintained, then the current remains low throughout the entire electrolysis. This means that the iron solution cannot reduce the oxide while the potential is applied and oxidation is occurring at the electrode. Acknowledgment.-This research was supported in part from funds granted by The Ohio State University Research Foundation to the University for aid in fundamental research and in part by a grant from the E. I. du Pont de Nemours and Company. DEPARTMENT OF CHEMISTRY THEOHIOSTATE UNIVERSITY COLUMBUS, OHIO
X-Ray Examination of Polychlorotrifluoroethylenel BY H. S. KAUFMAN OCTOBER24, 1952 RECEIVED
The X-ray investigation of the structure of polychlorotrifluoroethylene has been undertaken in order to obtain an understanding of the behavior of the polymer in terms of its structural parameters. The polymer, known commercially as KEL-F, is of interest because of its chemical inertness, low solubility, high softening point, and satisfactory electrical and mechanical properties. The development of crystallinity a t temperatures below the first order transition temperature a t 211’ has been investigated by X-ray methods. The data supplement those obtained by Price2using optical methods. Debye-Schener diagrams of the polymer were obtained using crystal monochromatized CuKa radiation and a flat camera. The patterns of unoriented polycrystalline samples showed one strong line a t about 5.5 A. and several other relatively weak lines a t smaller spacings. A high resolution Geiger counter spectrometer was used to study the fine structure that had been observed in some of the Debye-Scherrer patterns of highly crystalline samples.
1
5
Fig. 3.-Effect of oxygen pre-polarized electrode standing in As(II1) solution prior to electrolysis.
(1) This paper was presented at the Diamond Jubilee Meeting of the American Chemical Society held in New York in September, 1951. (2) F. P. Price, THISJOURNAL, 74, a l l (1952).
n = no of monomer units per unit cell = 14 Typical spectrometer patterns of the 3.3 A. reI' = volume of unit cell = 1290 A 3 gion of sainples of rarving degrees of crystalliriitjr are presented in Fig. 1. 'l'he quick qwiichiri~t c t :L T h e c,ilculated value is 2.10 g./cc, in agreement low temperature of Idyiiicr heated alia\ e Its with the value oT 2.1% g.;'cc. determined experitransition temperature results in a glass-cleu w n - inentally by the flotation method using a solution of ple which gives a low iiitvnsif 1)i oat1 diffr,tctioii r.y,n-tetrabroInocthaiie and diethyl phthalate. line characteristic of a rclati;. riy disordered diiiotAcknowledgments.--The author is grateful to phous structure (Fig. La). Extensive crystalliiiity Drs. E. Solomon, I. Fankuchen and D. Harker for with increasing opacity is developed by lengthening their h-, Experimental in the most oriented sample, sharp spots wr-e Reagents.-NN'-dihIeen, S S ' - d i E t e n , lT'-di-n-Pren formed. The spacings and relative intensities of these spots were in exact correspondence with the and NS'-di-n-Buen3 were prepared by the method of Schneider.4 SS'-di-i-Pren was prepared by a modification of the 5.5 A. region lines observed in the spectrometer procedure of Zienty,; using ethylene dibromide and isoprocurves of the niost crystalline sample. pylamine. One mole of ethylene dibromide was refluxed Measurement of the lateral spacings along the vvith five moles of isopropylamine for 2-4 hours. The mixture became almost solid with crystals. An excess of 20% row lines ol the fiber diagrams and of the lines ob- sodium hydroxide solution was added and the mixture disserved in the Debye-Scherrer pattgrns gave a se- tilled over solid sodium hydroxide. The amine was then ries of spacings, beginning with 3.6 X., which were in distilled over sodium; yield 6070. Both dl-bn ant1 iiz-bn were prepared by reduction of dithe inverse ratios oi I t/ ~'47~': : 4:). Tliese inethylglyoxime with platinum and hydrogen in a Parr ratios, being characteristic the hexagonal system, bomb iU07Gyie1d)O and also bq reduction with Raney nickelsuggested that the polymer chains were pac1;ed in aluminum alloy and aqueous alkali (41% yield).7 The hexagonal unit cells. One dimension Of the unit second method was found to be the most convenient in spite of the low yield because i t could be carried out on a larger cell was calculated Irom these dat'i and found to scale. The mcsa aiid racemic bn's were separated by fracbe 6.3 4. The repwt clistarice ,t!o:ig t h e Llxr axis llization of the dihydrochlorides from methyl was determined to be 33 froin measureint sits of r. u a c e i ~ i cforin is about eight times more soluble the layer-line separation of the spots. These &ita than the wzcso form at room temperature. The free amines liberated by the reaction of the calculated amount of established the unit cell to be hexagonal, with the were sociium niethoxide with the dihydrochlorides in absolute nlrohol, followed by distillation under reduced pressure. dimensions A = ci.5 -%. and C = A. iso-1311 was prepared by the reduction of a-aminobutyroOne structure which xcountg for the extraordi- nitrile with lithium alurriinuin hydride in anhydrous ether. narily long fiber spacing of 35 A. is a spiral chain Eight>.-four grains of a-nminoisohut!-ronitrile in 200 ml. of arranged so that the spir,il starts to repeat itself mhydrous ether was added dropivise, over a period of two after approximately 1 1 iiioiioincr unit.;. This houri, to . I wcll-stirrcd clurry OC 76 g . of LiAlM4 and 2 1. of structure is similar t o that ~vlitchhas bceri ,iss;qiied rcitigation was snpported h y a p x n t - i n - a i d from the to the spiral of polyisobutylene 2nd of Teflon. tiitcs o f He:iIth; G r a n t S o . G-323'3. l o .ind R . K. M u r m a n n , T H I S J O U R N A L , 74, 2373 (1932). -A planar zig-Lag chain such as in pol)-vinyl chloride mines d i s x s s e d h e r e are designated as follows: h-K'or polyethylene is ruled !>utbecause it requires a fiber dil\Icen = S,S'-diniethylethylenediamine; I\"'-diEten = N,N'axis spacing of about 5 A. d i ~ ~ t l i y l e t h y l i . i i e d i a m i n e ;S N ' - i l i - n '-di-ii-propylethylOn the basis of this assumed structure, t h e density e n e < i i a m i n e , X X ' - d - i Pren = of the po1ymc.r may be c-dculated usinr: t h r t'cjil;tti~)ri SS'-di-;z-Bricn = S,S'-di-?z-butp 17,
~~
ii
where
=
:tininropa?ie(~irol)~Ienediamine);iil-bn = rac-2,X-diaminohutane; l e - b n = nir,s~j-2,3-iliatiiinobutane; isu-bn = 1, 71'ctraMFc:i = 2 , 3 - d i ; i m i n o - 2 , 3 - d i n 1 c t t , ~ l t ~ ~ t a n e ; ~iii~lieiir.lrtl~ylcn~~li~ n -~s~t i~e i in e = ;: mesii-1.2 :j
mine.
