1063
Sovember 1969 TABLE I C.\KCINOOESIC POTESCY O F HYDKOC L K B O S ~S T C ~ J I E i xDTHI:? Isvss~ic;.~~ricis potency (or activity)'I------Ref 1 i
--------Carcinogenic Ref 16
Co1npd
R e f 18
+
S m r aliiits repurteti in rei
Beiiz[a]aiithraceiie ( I ) Iiiactive 1-ticertairi 14 S I: 14 7-l1ethylbeiiz [u]aiithracaeiie (I1 I SI: 14 7,12-I>imethylbeiiz[alanthraceiie (111) t+++ ~)-J\leth?.l-i,X-ethaiiobeiiz [a]arithracetie XI: (20-niethylcholaiithi.eiie) (1\ ' ) 14 I)ibeiiz[ci,h]arithraceiie (\'j 14 Benz [a]pyreiie i\.I) 14, 1.5 t+++ t+tt +t+ sIt Heiizo[c]pheiiaiithreiie (\-II) b t I)ibeiizo[c,y]pheiiarithreiie I\'III) Iliac1 ive Iiiactive N 1: c Activity: vel'? marked: vel'. weak: XI? meail.. r i o t repoi,ted. * K. I ) . Bartle aild I). K. Jories, J . Chrm. Soc., d, 4x7 (1969). c K. I>. Bai,tle, I). by, Joties, aiid I < . S . l l a t t h e m , ibid., X i 6 (1969).
+++
+++ ++++ ++++ ++
++++ ++
++++,
'1
+,
Calcd Ilipule approxmrn (Paulinrr
~n ,,,,,,,
CT
j.
-----
H i1c lie1 L C.\O-------
Rei 38
I'ople inetliud Rei 11
-----;\lc\\.eeny Ret 3 i
I ,48 1.16
1.44 1.22
1.31 1.17
no deli
tIc 11 H(2)
+++
Tarislile
rnetliutl---Ret 39 Re1 :16
1.31 I 17
I ,2x IL . 1.i
P
SCF Ret 39
Ret 40
1.2s 1 . 1.5
1.24 1.OI4
Refined LC.\O----p indeInclusion pendence u i uverlap Re1 4 1 Ref :36
1, 3 9 1.21
1.20 1.11
1:xptl Ref 11
1.28 I . 10
suggest that ring-current hhifts for some shifts that they lie 011 ii subsidiary (brokeii) line protons deviate sigiiificarlt.ly from "simple" 1,CAO (E'igures 1-3) displaced -0.35 shielding unit (0.54 values. Compari on of c a l c ~ l a t e d ~and ~ ~ experi~ ~ - ~ ~ ppm) from the main line. mental proton-sh elding constarits. U~ u ~ ~ ,(with ~ ~ ~ ~ Several ~ , , ~explanations of this pheiiaiithreiiic protori respect to benzene), for naphthalene (Table 11) s h o w that LCAO-calculated shifth correlate ~ w l with l experi0 e mental values. It is coricluded that M comparison of / calculated mid experimental shifts in polynuclear / / carciriogeris should afford a measure of the applicability 2.0 / t o these compounds of LCdO theory or1 which the l'ullman theory1ij21,22 of carciriogeriesis depends. Low symmetry and or poor solubility rerider the / / measurement of chemical shift>siri many polyriuclear / carcinogens difficult from iimr spectra recorded a t moderate frequencies; recent Iy, spectra for :I number of beiiz [a]aiit,hraceiies (of carciiiogenic potency given in Table I) have heeri a ~ i a l y z e dat ~ ~220 * ~ JIHz. ~ The f i r correlatioiis (I'igilres 1-3) betweer1 calculated3fl~37~42 shielding parameters, u 7 /uailellaelle, and values derived from the experimental shifts corifirm earlier valuations4' of ring-current calculations in the approximate solutiori of parent hydrocarbon spectra in terms of relative chemical shifts. with arialogous polynuclear hydrocarhoiis, bond anisotropies for peripheral protoris :ire small enough to be rieglected,r',12,"7,4" but ha,v protoris cxperieiice here such anomalously large dowiifield
I
/c
3
/
( 3 5 ) L. Caralp a n d .J. H o a r a u , . J . Chzm. /'/tu.\.. 66, 1,566 (1958). ( 3 7 ) .J. D. M e m o r ? . G . !V. Parker, a n d J. C. H a k e \ - , J . Chem. Phua., 46, 3567 (1966). ( 3 8 ) H . J. Hernstein, \\.. G. Gchneider, anti .J. .4, I'ople, Pro?. R o y . S O C . , A236, 515 ( l Y b 6 ) . ( 3 9 ) G . G . Hall. . i . Harrlkson, and I,. hl. .Jackman. U i * e u ~ s i o r , s/ + ' c z r ~ ~ d < g ~ So?.. 34, 15 (1962). (-10) ( a ) H . P . Fiaeys. T e h h e r i r o n L e t t e r p . 4625 (1966): (1,) Chem. Commuri.. 49.5 ( l g ! 3 T ) . (411 G . T V . Parker a n d .J. D. 3Iemors-, J . Chrm. I ' h y s . . 43, 1358 (1965). f 4 2 ) T . 13. Cohh a n d .1. 11. Ilernor!., ihid., 47, 2020 ( 1 9 R i ) . 143i K . G. Kiild. G G i i t i i ~ w k y .a n d T. Scllaefer. C,,t
