510
NOTES
more extensive, a progressive decrease in the A S * of the reaction takes place (lines 1 to 6 of Table 11). The AH* of the reaction decreases also as the inductive effect of the substituents increases. There is very little change in AH* on going from butanol-1 to 3-methylbutanol-1 (lines 1 and 2 of Table 11). However, on going from 1-butanol to 1pentaiiol AH decreases by about 1 kcal. (lines 1 and 3 of Talile 11). Xgain no further change in AH* takes place on going to I-hexanol (line 4). When an ethyl group is substituted on the S o . 2 carbon atom of I-hexanol, however, the AH of the reaction decreases again by about 1 kcal. (lines 4 and 5 of Table I1 ) . K h e n an isobutyl group is substituted on the :To. 1 carbon atom of isoamyl alcohol AH decreases by about 2 kcal. (lines 2 and 6 of Table 11). Interestiiigly enough, at looo, the apparent firstorder rate constant for the reaction differs but little in the xariou:: alcohols studied, despite the range in size from 4 to 9 carbon atoms. In each case, on passing from the more simple to the more complex nioleculw, the disadvantage imposed by steric hi1idranc.e is almost entirely compensated for by thc adv:uitage accruing from the lowering of A H , with the result that the AF* of the reaction remains practically unchanged in all six solvents. Ou going from n-butyric acid to 1-butanol AS* decreases by about 7 e.u. (lines 1 and 7 of Table 11). This result is in harmony n-ith the fact that the “supermolecule” of the associated alcohol is made up of three or four mononiers. whereas that ists of the d i ~ n e r . The ~ increase in e.u. on going from water to the acid (lines 7 and 8) also is in line with the fact that although the water molecule is considerably smaller than that of the acid, the associated complex of water contains many more nioiiomers than does that of the acid. For the reaction in n-butyl alcohol, isoamyl alcohol and aniliiie the Eyring parameters are very nearly q u a l (see lines 1, 2 aiid 9 of Table 11). This circumstaiice suggests that the electron and steric properties of these three liquids are closely parallel. I n compounds of the ammoiiia aiid water sybtenis containing the same types of substituents the nitrogeii is more basic in the Lewis seiise than is the oxygen (the oxygen atom is smaller than nitrogen and its nucleus contains one more proton than nitrogen). ‘This situation may be reversed, hovever, if compounds containing different types of substituent;: are considered. I n aniline the strong Ieffect OF the resonating aromatic nucleus greatly reduces the electron density on the nitrogen atom, uherea? in n-butyl and isoamyl alcohols the +I effect of tlie alkyl groups increases the electroii density on tlie oxygen atom. It is not too surprising, therefore, to discover that the AH* of the reaction iq about the same in these three liquidsin other vords, that they are about equally bait in the Lewis sense. At looo, malonic acid derompowls in aniline only 1.3 tinies as fast as in the t n o al(.ohols. This suggests that for other reac( Y ) it-. l l u t h e l Thcor a1 Piincii,les of Organic Ciieinistr\ ” Yo1 I1 LI,c\ici I ’ 1 I i l i ~ 1 ~ 1Cno~ S e w l o i h , N. Y . , 1‘358, 1,. 325 et Wz.
Vol. 64
tions which proceed in alcohols and amines by the same mechanism as the malonic acid decomposition, e.g., acylation,10 the rate of reaction at a given temperature should be nearly the same in aniline, n-butyl alcohol and isoamyl alcohol, and also the Eyring parameters should be nearly equal for the three liquids. When two alkyl groups are joined to the carbinol group, or are in close proximity to it. their combined inductive effects may cause the electron density on the oxygen atom t o exceed that on the nitrogen atom in aniline, as revealed by the fact that the AH of the reaction is lower in such liquids than it is in aniline (lines 5, G and 9 of Table 11). Acknowledgments.-The support of this research by the Xational Science Foundation, Washington, D. C., is gratefully acknou-ledged. (IO) R. Q. Brenster, “Oiganic Clieniisti>,” 2nd edition, PrenticeHall, I n c , K e a Yoih, K.Y., 1Q33, pp. 204 and 538
IJEH.1VIOKS OF C-D STliETCIIISG I3,lSDS IF POLYETHYLESE-d, TEREP€€T€IAII~AITE BY
.%ICIHISS I I I Y 4KE
Centr.al R e s e a r c h Laboratories, T o ~ oR a y o n Co.. Olsu. Shim J a p a n Received SoEembes 16, l B 5 B
The dichroism of t,he C-H stretching baiids in drawn samples of polyet,hylene terephthalate does not agree with expectation. I n spite of the parallel orientation of the polymer chain nith respect to the directioii of tlyo 1)ands at, 2970 aiid 2910 c n ~ . - assigned ~ to the aliphatic C-H stretching vibrat,ioiis show parallel d i c h r o i ~ m . ~ , ~ This parallel dichroism which is opposite to the predicted perpeiidicular dichroism, has been explained as a result of the overlapping of Tibrations of lrans and gauche ethylenedioxy (OCH&HzOj groups.7,z The gauche ethylenediosy groups in the amorphous region of t’he polymer may achieve completely different’ orientations with respect to the direction of drawing. The dichroism of the C-H stret,ching bands may be deterniiued by these gauche ethyleiiedioxy groups. In order to settle this poilit, more definitely, C-D stretching bands of polyethylene-d4 terephthalate have beeii re-investigated using L: LiF prism. Previous investigation of this polymer has only been done by t’helow dispersion S a C l prism.8 In quenched samples of polyethylene-& terephthalate, there appear three bands at’tributable t,o C-D stretching vibrations at’ 22G0, 2200 and 2130 em.-’. On crystallizing t’he samples by heating, two new hands appear a t 2275 a d 217.5 em.-’ (Fig. 1). On the hasis of a previously established relat,ion bctn-een the crystalline Ixnids aiid the rotational isoiiicrism for this p o l y ~ i i c r ,these ~ , ~ two ( 1 ) R . G . J. SIiller a n ~ 11. l -i.IVillis, T r a i i s . l::~i12duu S u e . . 49, 133 (1953). in:l S. ICriuniii, J . Ciiern. I C . Illinn a n d c‘. Dro\r-n. A226,531 ( 1 0 5 4 ) . (4) \V, J. Dulnisge and .i. L. Geddes, J . l’olr,iiier S c i . , 31, 4‘39 ( 1 058). Yeston, C/:cncistf)/ & I n d u s ( r r / . (j0-I :lC*.j4), Tollin. T i i i s J O L - R X A L , 57, 13!!2 ( i l l iinc nncl I. 1 1 . \Vnrd. T r a i t s . Faind 54, ‘359 (1058). y : ~ k e ,J . I ’ u i u m e ~ Sci., 38. 4‘37 (19
CORIIVIUNCATION TO THE EDITOR
April, 1960
4.4 Fig. 2.-Dichroisms
I
I
I
3.4
4.3
4.6
I
4.7
I
4.8
P.
Fig. 1 . 4 - 1 ) stretching bands of polyethylene-dd terephthulate: (A) quenched; (B) annealed.
baiids caii be attributed to the C-D stretching vibrations of ethylenedioxy groups which exist in the trans form, while three baiids observed in quenched samples can be attributed to ethylenedioxy groups in the gauche form. The lowest C-D baiids of the gauche form seem to be composed of two vibratioiis. The reason for the shift of its peak on crystallization is not clear. (9)
.I. Miyahc, J . I'olymei
& I . , 38, 479 (1959).
51 1
4.5
4.6 P.
47
4.8
of the C-D stretching bands.
Now, in an oriented and aiiiiealed sample, the two crystalline bands a t 2275 and 2173 cm.-l apparently shou- perpendicular dichroism which is in agreement with the parallel orieiitatioii of the chain. On the other hand, three baiids attributed to the gauche form show parallel dichroism (Fig. 2 ) . Thus these results give confirmation for the interpretation of the C-H stretching baiids of polyethylene terephthalate referred to above. Since the symmetric stretching, antisymmetric stretching and wagging modes of a CH, group have mutually perpeiidicular transition moments, Liang and IZriinm'" have past doubt on assigning the CH2 wagging vibration to a parallel band at 1345 cin.-' in polyethylene terephthalate. Hot\ ever. from the results obtained in polyethylene-& terephthalate, it seems almost certain that perpendicular C-H stretching band- of the trans form lie huried under the gauche bands, and hence the parallel band a t 1345 cm-' can iio~vbe reasoilably assigned to a CI32 wagging mode of trans ethyleiiedioxy groups. Experimental The samplt's are the s m i e ns those in LL previoiis research.8 The infr:trcd nbsorption measurement n r r e carried out 1 ) j a Perkin-Elmer 1Ioilcl 21 sprsc%rometernitli '1 LiF prism. (10) C Y Lian:! and 5 Krinim, J . Chem. P h y s . 27, 1437 (15357).
COMMUNICATION TO THE EDITOR THE hfEI~CUIZY-SESSITIZEDItADIOLYSIS AND I'IIOTOLYSIS OF XETHAX E ' Sir:
molecule mechaiiisni bared originally upon mass spectromet,er studies." We have uiidertakeii the study of the radiatioii chemistry of riiethaiie in the presiice of mi almost, six-fold esress of iiiercury The ratliatioii rheniistry of pure methanc? vapor so that charge trniisi'er reactions of the type aiid the argon aiid krypton seiisit,ized radiolysis of CH,+ f Ilg --f CH, + f i g (1) methane3 have been described rccently. These should eflectively srnvenge h?-droc~~t)c 111 molcculo investigations were iiitcrpreted in ternis of an ioiiions which survive neutralization. AUt,hough ( 1 ) This n-oik \vas pc,rfoi ~ i i r d iintlcr tile aiibpiccs of t h e U. S. Atomic quaiititat~ivedat,a are not, arailnhle for equation
( 2 ) 1'. \V. L:niilic'. .J. .lm. C k t n . S o c . , 79, 10.53 (11357). (:i) C:. G , ALeisels, \V. IT. Haiiiill and K. K. IVilIiaiiis, .Jr., Tms . J o r ~ r a61, ~ , 145ti (1057).
m d 1). !'. Rtc\-ciison. .I. Chern. i'tws.. 2 4 , C:. Aleiscis. TV. 11. IIaiiiill and It. R . W'illiaiii~,.Jr.
!ii,.a!c,r
ibid., 26, 7130 (l%Ii!.
