iiiol~of haloalkyl ether. The required volumc of phenyllithium solution was added from a calibrated dropping funnel, over a period of 1.5 hours, to the haloalkyl ether in solution in 50 ml. of diethyl ether. Mechanical stirring was employed, and addition was a t room temperature without cooling. The reactions proceeded smoothly, with mild refluxing. The Michler ketone color teste was negative a the end of the addition (except in the case of l-ethoxy-3chloropropane), indicating absence of phenyllithium. Occasional color tests made during the cuurse of the dditioti indicated that reaction was immediate, since such tests were :tin-ays negative. The reaction mixture 1va.s cooled in an ice-bath and hydrolyzed by the addition of aqueous aniinonium chloride. After separation, washing with xr-atcr, and drying on Drierite, the organic layer was 42-em. Fenske column ('ja-in. glass helices) separate the diethyl ether, benzene, and othe products. The higher-boiling portioii was then distilled under reduced pressure through a 25-Cm. Vigreux column. For certain reactions, data iiot apparent from Tahlr I are I:i\-en below. 1-Methoxy-I-&loroethane.--The l-methoxy-l-pheriylethane had b.p. 54-57' (11 mm.), n% 1.4918; thereported'" b.p. is 55-57' (11 rnm.). For derivatization, a sample of 8 g . of this product was coiiverted to the iodide by 12 hours of refluxing with 80 ml. of 47% hydriodic acid, and the iodide n-as identifiedll as the S-:ilkylisothiouroniiii~i pirratc,, in.1). 1fix--169' 1-Methoxy-2-bromoethane .---The reaction apparatus was attached to a series of three gas-washing bottles, each containing a solution of bromine in carbon tetrachloride. After the reaction was completed the apparatus was flushed out with nitrogen, while still connected to the absorption train. The contents of the gas-washing bottles were then washed with sodium bisulfite solution and with water, separated, dried on Drierite, and distilled to recover any ethylene dit)roniide. Sone was found in this case. However, the distillation of the main reaction mixture yielded 6.0 g. of an iiiipure fraction, b.p. 10-66" (10 nini.), which contained some bromobenzene, as shown by its conversion, through t h e Grignard reagent, to benzoic acid, n1.p. 132". The .l-methoxy-2-phenylethane, b.p. 66-70" (10 nim. j , iCii> 1.5001, reported12 t 2 . p . 70-7.1' (12 inm.), had the char-
.
-.
and F. Schulze, THIS JOURNAL, 47, 2002 (1926). , 0.Schichtinq, K.Klagcr and ' T Toepel, . I I ? ; I , 660, I (1!448). 111) W. J. Levy and h-. Campbell, J . Cheiii. SOL.,1442 (lW91. (123 S. S. Deshapande, J . IvJi(i?i Chriri. Sei.. 16, 509 :l9:18) I(' .1 33, 2281 (193R)I
JCmmIBvrIox FKUM
nrE
L)EPARTMBL r
acteristie sweet odor. A i-g. sample \~:iscorivertetl to 1 iodo-2-phenylethane by boiling for 11 hours with 80 ml. of 47% hydriodic acid, and the iodo compound was derivatized as the S-allrylisothiouroniurn picrate,11 m.p. 138-139". In other experiments, as shown in Table I, the conditions of this reaction were varied in order t o improve the yield. The best result was obtained when 0.22 mole of phenyllithium in about 200 ml. of ethyl ether was added slowly to 9.33 mole (50% excess) of 1-methoxy-2-bromoethane in 90 ml. of ethyl ether, cooled and stirred in an ice-bath. 1-Ethoxy-2-bromoethae.-Bromobenzene and l-ethoxy'-phenylethane, b.p. 78-79' (10 mm.), T Z ~ O D 1.4976, reported13 h.p. 198-199" and nS*D 1.4870, were identified as indicated above. The presence of ethylene was not i l l vestigated. l-Methoxy-2-iodoethae.-The procedure described above was used for the detection of ethylene. The ethylene" dibromide, b.p. 130-134", obtained by distillation of the product from the gas-washing bottles, was characterized as the Salkylisothiouronium picrate," identified by rn.1). (259-260') and mixed m.p. with an authentic specimen. 1-Ethoxy-1,2-dichloroethane.-In this reaction two moles of phenyllithium was used per mole of haloalkyl ether. The I -ethoxy-1-phenylethene, b.p. 93-98' (18 mm.), n P o ~ 1.5299, reported5 b.p. 109-112" (30 mm.) and n 2 5 J ~1.6287, was hydrolyzed by heating with alcoholic hydrochloric acid .: The resulting acetophenone was converted t o the semicarb;tzone, which was identified by m.p. (198-199') ant1 rnisetl m.p. with an authentic specimen. 1-Ethoxy-3-chloropropane.-When this reaction was carried out under the above conditions, reaction was much slower than in the case of the a- or &haloalkyl ethers. The color test9 was strongly positive a t the end of the addition, and the final products included benzene in34% yield. This is not shown in Table I, since it could have come mostly from unreacted phenyllithium. The l-ethoxy-d-phenylpropane wa.s converted to the iodide as above, and the latter was identified by converting it to the .Grignard reagent arid then carbonating with solid carbon dioxide, to give 3-phenylbutyric acid, m.p. 47-48'. The reaction vas repeated as above, except that after addition was complete the mixture was refluxed until a negative color test was obtained (3.5 hours). This treatmelit increased the yield of the coupling product, l-ethoxy-:jpheriylpropaiie, b.p. 90-95' (10 mni.), n2% 1.4938, Ti'ported'-' h , p . X:5--90a (20 mtn.'i. .
~
. . ~...
~
13) J . Wwtheim, T m s JOURSAL, 59, 2472 (1937). (14; .i .M. Nelson and A. M . Collins, i b i d . , 46, 22X3 ,111241 t
,
(;usn FOKKS,SORTH I).%KOTA
OF C F r E M I s ' r K Y , [ . S I V E R S I T Y O F
CALIPOKSIA 41' I).%vis ~
Polymethylbenzene Complexes of Iodine and Iodine Monochloride BY L. J.
. ~ N D R E W SAND IVEI)
R. M . KEEFEK
~ I A K C3H, 1H:iZ
Previous studies of halogen-aromatic interactions have been extended using inodified procedures to include several of the polymethylbenzenes. The relative magnitudes of the equilibrium constants for the formation of 1:1 complexes with iodine or iodine monochloride of the various methylated benzenes have bcen found to parallel in general the tendency of the aromatic substances t o undergo interaction with hydrogen fluoride-boron trifluoritie solutions. Equilibrium constants for thc interaction of iodine monochloride with ethyl-, isopropyl- a n d i-butylhenzene were also measured and were found to he, withiii rlose limits, the iame a\ t h a t for tohietic. Theorrtic:tl aspect.: of thew findings have been considered.
The generalization that increasing methyl substitution enhances the basic character of the aroniatic nucleus is best illustrated by the work of McCaulay and Lien.' These investigators have observed that, with certain exceptions, the tendency for methylbenzenes to fonn complexes of the type k H f B F 4 - in hydrogen fluoride-boron trifluoride solutions increases as the number of rirlg methyl substituents increases frorrl one to six, similar order of stability has been shown to apply t
( 1 1 1~) .A, LicC'atilay and 4. I' w51 '.
l,ieiL, ' L ' H I ~ l i i t . n y a i . , 7 3 , ? i l l : {
to the benzene, toluene and xylene complexes ( d silver ion,2 bromine, iodine monochloride4 arid sul-fur di0xide.j The mesitylene-iodine complex is inore stable than that of benzene agd iodine.'; However, with silver ion mesitylene' yields a com-
plex which is less stable than that formed by benz12) (a) L. J . Andrews and K. M . Keefer, i b i d . , 71, : m i 4 i i ! t ~ w M.Keefer and I,. J . Andrews, i b i d . , 74, 640 (1952) I: f , Keefer, i b i d , , 7 8 , 4169 ( l < + z l , H. .%. Benesi and J . H . Hildehrand, ibid., 71, 2703 (1!44$l 7 ' I I . .Andrew a n d R . M. Keefer, i b i d . , 72, 6034 ( 1 4 5 0 i .
'hl R.
Sept. 20, 1952
POLYMETHYLRENZENE COMPI,EXES OF IODINE .WD IODINE MONOCHLORIDE 450 1
ene. The failure of the mesitylene-silver ion com- calculate equilibrium constants for the formation plex to exhibit normal stability has been explained of 1-1 complexes by means of equation 1. in tenns of a steric deet (opposing complex formation) of the several methyl groups of the mesitylene molecule. I n view of the low stability of the mesitylene- The terms (X& and (A)t represent the total silver ion complex it has seemed desirable to deter- inolar Concentrations, respectively, of halogen and mine whether the stabilities of the halogen coni- aromatic compound. Values of K , have been calplexes of highly methylated benzenes are also ab- culated in terms of molar concentrations { L e . , for all reacting species normally low. The equilibrium constants for K , = (.I+X2)/(A)(Xz)] rather than by the method of earlier investigations formation of 1 :1 complexes with iodine and iodine monochloride of mesitylene, durene, pentamethyl-, in which the concentration of the aromatic subhexamethyl- and hexaethylbenzenes have now been stance was expressed in terms of its mole fraction. determined by a modification of the spectrophoto- This procedure was adopted to facilitate calculametric . procedure used previously. The equilib- tions based on measurements on the dilute solutions rium constants for complex formation of benzene, employed in dealing with aromatic compounds toluene and the xylenes with the halogens have which are solids a t room t e m p e r a t ~ r e . ~The use been redetennined by these improved procedures, of dilute solutions of the aromatic substances and the interaction of iodine monchloride with eliminates the shift in the wave length of maxiethyl-, isopropyl- and t-butylbenzenes has also been nium absorption of the halogen complexes noted in investigated. Equilibrium constants for halogen studies on more concentrated solutions. Values interaction of several other aromatic compounds of (1, were obtained by correcting the measured optical densities for the absorption of free halogen have also been determined. in the solutions. These corrections were calculated by procedures described previously. For each Experimental Materials.-Samples of Eastman Kodak Co. white label series of measurements plots of ( X ? i t d, against grade durene and of pentamethyl-, hexamethyl- and hexaI (A)t (based on at least 3 points) gave straight ethylbenzenes were used without purification. The mesi- lines, and the values of 1 'e, and 1 'h-,e, obtained tylene, a sample which had been purified by the procedure from the intercepts and slopes of the plots were of Smith and C a s , * was furnished by Mr. John H. Blake. All other materials were purified as described in connection utilized to calculate the values of e, and K , appearwith the silver ion complex studies. ing in Table I. (eC represents the molar extinction The Absorption Spectrum Measurements.-As in earlier coefficient of the complex a t its absorption maxir n ~ r k ~a ,series ' ~ ~ of carbon tetrachloride solutions of varying concentrations of the halogen and the aromatic substance mum.) The equilibrium constants reported here were prepared a t 25". The optical densities of these solu- are, insofar as there is duplication, in fair agreetions a t the complex absorption maximum (usually in the ment with those obtained in previous work using neighborhood of 300 m p ) were determined using as a blank more concentrated solutions of the aromatic suba halogen free solution of the aromatic compound, of the same concentration as that of the solution under measure- stances, I n general the wave lengths of maximum ment. In the present proced~ire,~ which was designed to absorption of the complexes in dilute solutions of the permit the investigation of aromatic compounds which are aromatic compounds ( i e . , about 1 M) are shifted solids a t room temperature, the concentration of the aro- 4 to 3 n i toward ~ the ultraviolet from those found matic material in the complex solutions generally did not for the concentrated solutions ( A V ~= 1). Howexceed values much greater than 1 ill. The concentration of halogen in solution was so adjusted that the optical deti- ever the values of e, reported here agree (within the sity a t the complex absorption maximum ranged between limits of error) with the values obtained in working 0.300 and 1.00 when 1-cm. absorption cells were used. The with concentrated solutions. cell housing of the Beckman spectrophotometer used in these The methylbenzene complexes with both iodine measurements was maintained a t 25". Insofar as possible measurements were made a t slit width settings of 0.6. All and iodine monochloride fall in the same order of optical densities were corrected for the slight absorption of stability as has been reported by hIcCaulay and the uncomplexed halogen. Lien1 for the interaction of these hydrocarbons In making optical measurements on solutions of iodine with HF-BFa. This order of stability is as follows : monochloride and certain of the aromatic substances (noticeably with the polymethylbenzenes), it was observed that the toluene < xylene < durene < mesitylene < optical densities a t the complex absorption maximum di- pentamethylbenzene < hexamethylbenzene. Conminished with time. Whenever this phenomenon was cn- tary to the findings of McCaulay and Lien the countered, a series of optical density measurements as a function of time over a short time interval were made imme- results of this investigation indicate that of the diately after preparation of the solutions. These data were xylene-iodine monochloride complexes that formed used to estimate by extrapolation the optical density of the by the para isomer is the most rather than the freshly prepared solution. least stable. However the observed stability The cause of the observed changes in optical density with time is now under investigation. Preliminary work indi- differences for the halogen complexes of the three cates that iodine is formed as a product of the reaction which xylenes are small. occurs. Although an ethyl substituent appears to enResults hance the basicity of the benzene ring to the same In this investigation, as in previous investiga- degree as does a methyl substituent (cf. K , values tions, the spectrophotometric data obtained using for the benzene, toluene and ethylbenzene comcarbon tetrachloride solutions containing both halo- plexes with iodine monochloride), hexaethylbengen and aromatic substance have been utilized to zene is an extremely poor base as compared to hexamethylbenzene. The hexaethylbenzene-iodine (8) L. I. Smith and 0. XY. Cass, THISJ O U R N A L , 64, 1606 (1932). K,value than that of benzene, complex has a lower (9) This method is similar to that employed by PIT. W. Blake, H. Winston and J . A. Patterson, ibid., 73, 4337 (1451).
(10) R. M Reefer and L. J Andrew,, rbid
, 74, 468
(1052)
'l'.\!J!,k.
EQULLIBRIW COSSTANIS
FOR
1 1-
ASD
IC1
C(1hfPLEXES O F
AROMATIC SVBSTASCES 11- C A R B * J U FI'ETRACIILORIDE AT
25"
Uenzenc '~(JlUeliC o-Syleiie ~-~Xylerie p-xylelle LIrsityleiic
Lkirene Pentarriethylbenzeile I Iexamethylheiizerie Hexaethylhenzenc Brornobenzene Phenant hreric s apht halrll e Styrene St ilheiic I3il)rnzyl
i o n to ensure that the mesitylene reaction did not represent an anomalous case. It was found, however, that with the exception of durene the available polymethylbenzenes were insufficiently water soluble for argentation studies. Argentation constants for durene were determined by measuring the solubility of the aromatic conipound in aqueous silver nitrate solutions adjusted to an ionic strength of unity. The method of measurenient m d of calculations to deteniiine the equilibrium constants were the same as those used previously. The argentation constants for benzene, mesitylene and durene a t 25' for the reactions rigXg"
+ Ar = AgAr+ k'l = (AgAr+)/(Ag+)(Ar) + AgAr- = Ag2Ar+T
(2)
KS = (Ag,Ar++)/(Ag+)(AgAr+) (3)
are as follows: benzene, KI = 2.41, Kz = 0.21; mesitylene, K1 = 1.8 (no Kz)'?; and durene, K1 = 2.05, l i z = 0.34. Although durene gives a slightly greater argentation constant than does benzene, its reactivity is considerably lower than would be anticipated in terms of the electronic effects of the methyl groups. The fact that these methyl group steric effects were not observed in the halogen interaction studies lends credibility to the suggestion made earlier that the steric effects observed in argentation studies may result from interference between ring methyl groups and water molecules i n the hydration sphere of silver ion. Ethyl-, isopropyl- and i-butylbenzene within close limits give the same Kc values for interaction with iodine monochloride as does toluene. If these complexes were subject to appreciable stabilization because of enhanced ring electron density resulting from hyperconjugation involving a-hydrogen atoms of the alkyl substituents, the K , values for these benzene derivatives should decrease with change in alkyl substituents in the order CH3- > CHCHp- > (CH&CH- > (CH,),C-. On the basis of the inductive effects of these groups N. W. Blake, H. Winston arid J . -4. Patterson, THIS one would predict the opposite order of reactivity. TOURNAL, 73, 4437 (1951), report for the riaphthaleneiociiiie complex in carbon tetrachloride the values A,,,,, 360 I t is possible that the almost identical reactivities inp, EmAX 7269, A ' , 9.257. of the alkylbenzylenes as noted in the present study may result fortuitously through combination of and with iodine monochloride the equilibrium these opposing electronic effects. Lichtin and constant for the interaction with the hexaethyl Hartlett have offered interesting comments on the derivative is about the same as those for the problems inherent in theorizing on the basis of a xylenes. The low stability of the hexaethylbenzene series of measurements which reflect the resultant complexes can be explained in terms of unfavorable of both effects.'? steric effects resulting from the high concentr a t'ion The remaining compounds for which equilibrium of ethyl substituents on the aromatic nucleus. .I constants were reported in Table I were investiconsideration of molecular models shows that, gated primarily to determine whether the stabilities regardless of the structural configuration of the ( I f their halogen complexes parallel those observed addition complexes, six ethyl substituents or1 the for their silver ion complexes. The halogen conibenzene ring offer much more inhibition to the plexes of bromobenzene, naphthalene, stilbene arid approach of reacting halogen to within the sphere of bibenzyl have the same order of stability as do the interaction of the aromatic *-electrons than do six silver complexes of these compounds. One marked methyl substituents. deviation in behavior was noted in the case of the Since in the silver ion studies the experimental styrene-iodine complex. In this case a K , value evidence indicated that even with mesitylene a approximating that for the xylene complexes was methyl group steric effect opposing aromatic- obtained. The argentation constants for styrene, silver ion coordination existed, it seemed of in- however, were sufficiently large as to suggest that terest to determine equilibrium constants for the I121 The K Ivalue for mesitylene waq checked with carefullv purified interaction of polymethylbenzenes with silver material and found to agree verv well with that reported previou i l l ) See for various viewpoints references 2-6 and also R. S. hlulli ken. Trm JOURNAL, 72, 600 (19.50). 74. 811 (19.52)
(13) ?; V I ichtin a n d P 1) Hartlett, THISJ O U R . L A L 73 1( 2 -,1
Sept. 20, 1952
ACTIONOF HYDRAZIDES OF XICKELDISALICYLALDEHYDE
the silver ion in this complex was coordinated mainly a t the vinyl side chain rather than with the ring. Although phenanthrene forms a more stable silvw ion complex than does benzene, the K O values for the iodine coniplexes of these aromatics
4503
are the same. I t is possible that the phenanthreneiodine results are somewhat in error as spectrophotometer readings, in this case, were made a t high slit width settings, a procedure which is undesirable where high precision is required. DAVIS,CALIFOKSI.4
[CUVTRIBLJrICIs FROM T H E ISTITUTO D I CHIMIC.4 FISICA D E L L ' UNIVERSITA
DI FIRENZE]
Chemical Reactions of Complexes. I. Action of Hydrazides on Nickel Disalicylaldehyde BY LGIGISACCOSI RECEIVED MARCH
31. 1YSL
The reaction of hydrazides of the type H&-NH-CO-R with nickel disalicylaldehyde (or with nickel acetate and salicylaldehyde) is dependent on the nature of the R group. If R = alkyl or arylalkyl, symmetrical paramagnetic ionic compounds are formed. If R = Ph or substituted Ph, bicyclic planar complexes are formed.
Starting with the first syntheses of Pfeiff er and co-workers, inany complexes of metal o-oxyazoiiiethines have been described.
molecule of salicylidenebenzoylhydrazine reacting in enolic form, as represented by the reactions shown. These complexes, orange to red in color, are insoluble and stable in concentrated aqueous alkalies. .They are diamagnetic and therefore have a planar arrangement of dsp' covalent bonds. The H---0 bond in formula I accounts for the stability of the On treating nickel disalicylaldehyde with hydra- four planar bonds as well as the stability toward alkalies. The formation of bicyclic complexes when Of the type H2N-"-C0-(CH2)n-K! where represents Or phenyl groups! his- R = phenyl and = 0 is undoubtedly due to the enolizing influence of the CaH5-CO- gioUp, salicylidenehydrazides of the following structure compared with that of the alkyl -CO- and the are formed phenylalkyl -CO- groups.? R-( CH,h-CO The bicyclic complexes are slowly transformed into symmetrical complexes by reaction with saliSH cylaldehyde, either liberated from nickel disalicylaldehyde or added as such. This type of reaction ,-can be represented by I + H@-CsI€4--CHO +
'
,
S I-I
CeH:,-C--.OI
i
1; s
i
CCr(CH2L-R These complexes, green in color, are paramagnetic with a moment of about 3.3 Bohr magnetons. They therefore have four ionic sp3bonds and a tetrahedral configuration. If K = phenyl and n = 0 , two series of cornpounds are obtained. Initially formed are bicyclic com-
i
I1
I
S
/I
+ Hz0
HO-C-CcHi,
These complexes, greenish-yellow or XH=O. O b 0 yellow in color, are soluble in sodium -1- zH2N--.xH -co--ca; hydroxide solution, from which they > -0' >si('TJ< C f I L.... are precipitated by carbon dioxide or acetic acid. This behavior indicates an enolic form of the hydrazidic group. S=C-CeHj These substances are paramagnetic with ~ . t t corresponding to two unpaired elecS i trons, indicating a probable tetrahedral liO---C&r--CHO f HIO + structure. I o-Aminobenzoylhydrazint: is an exception, however, since the following plexes containing a tridentate group produced by a asymmetrical paramagnetic complex is first
