FREDERICK R. JENSEN
1226
heated by means of a n oil-bath a t 135'. T h e slurry of sodium acetone oxime was added in small portions over 1 hr. and the subsequent mixture stirred and heated for 24 hr. After cooling, the reaction mixture was filtered t o remove the insoluble solids. The brown filtrate was distilled through a 42-cm. Vigreux column and the fraction boiling above 92" (20 mm.) collected. The lower boiling portion was distilled again and additional material boiling above 92' (20 mm.) collected. .Ipproximately 40-50 g. was accumulated in this manner. Two more distillations gave 22-38 g. (29-51%), b.p. 40-45' (1.5 mm.), 98-99' (20 m m . ) , n z 6 1.4259, ~ of a colorless oil. Anal. Calcd. for CgHigr\;03: C, 57.1; H , 10.1. Found: C, 56.5: H. 9.9. The unchanged bromoacetal can he recovered from the lower boiling distillates with little trouble A . The acid hydrolysis of acetone 0-(2,2-(diethouy)ethyl)-oxime ( V I I ) in the presence of a n excess of acetone: In a solution of 35 ml. of acetone and 19 ml. of 1% hydrochloric acid were dissolved 2 g. (0.0212 mole) of acetone 0-(2,2-(diethoxy)-ethyl)-oxime ( V I I ) . After refluxing for 1 hr., the solution was cooled in a n ice-bath and then neutralized with anhydrous potassium carbonate to p H 7.58.5. The acetone was removed by evaporation in vacuo at temperatures not over 45'. T h e residue was chilled in a n ice-bath and extracted with three t o four portions of ether. Anhydrous sodium sulfate was used as a salting-out agent to ensure complete extraction. The ether extracts were dried with anhydrous sodium sulfate. After evaporation of the ether, 1.3-2.5 g. of a slightly yellow oil was obtained. This crude product decomposed even on vacuum distillation, and i t was not possible to obtain pure material. However, the oil gave the typical tests expected for a n aldehyde (Schiff and Tollens tests) and is probably crude acetone O-formylmethyloxime (VIII). ilttempts to prepare several aldehyde derivatives were all unsuccessful. Treatment with dilute aqueous hydrochloric acid gave a white insoluble precipitate similar in its thermal properties to the polymeric material described in part B. B. T h e acid hydrolysis of acetone 0-(2,2-diethoxyethyl)-oxime with aqueous hydrochloric acid in the absence of acetone: When the acetal, acetone 0-(2,2-(diethoxy)ethyl)-oxime ( V I I ) , was hydrolyzed in 1:l or 2 : 1 1% aqueous hydrochloric acid-95% ethanol in the absence of acetone by refluxing for 15-60 minutes, a cream colored t o white gummy insoluble material was deposited. On drying over PzOs in vacuo, it became more friable and amorphous.
[CONTRIBUTIOS FROM
THE
Vol. 79
Two grams of the acetal gave about 0.55 g. of this material. The sample analyzed below melted over the range 90-1 90" dec. and gave positive Schiff and Tollens tests. Anal. Calcd. for C2H3SO(=NOCH2CH=): C, 42.4; H, 5.3. Found: C, 42.9; H , 5.9. This analysis suggests the material to be polymeric in nature and composed of the units =NOCHzCH= since the carbon and hydrogen content of possible monomeric products are much higher than t h a t found for the material isolated. Serine ( I X ) .-The attempted synthesis of 3-aminooxy-2aminopropanoic acid via the Strecker reaction and the isolation of serine (IX): Material believed t o be crude acetone 0-formylmethyl-oxime ( V I I I ) (4.1 g., 0.0356 mole) prepared as described above was added t o 7.2 g. of 10% methanolic ammonia. T o the resulting solution was added ammonium chloride (2.86 g., 0.534 mole) dissolved in 17 ml. of water. The mixture was heated a t 80" for 4 hr. The dark red solution was cooled and then added to 50 ml. of concentrated hydrochloric acid (hood) and allowed to sit overnight. T h e next day, the solution was heated on the steam-bath for 3.5 hr.; additional acid (20 ml.) was added and heating continued for 6 hr. longer. T h e solution was then evaporated t o dryness in u " o and the residue redissolved in water and filtered to remove a black insoluble material. The clear brown colored filtrate was passed through an IRA-400 strongly basic anionic eschange resin to remove the anions from the solution. The resin was then eluted with 2 :I7 hydrochloric acid t o give an amino acid effluent which was identified by mean5 of the iiinhydriii test. The fractions containing the amino acid were evaporated to dryness and treated with silver carbonate (0.1068 equiv.) to remove chloride. After removing silver chloride, the filtrate was saturated with hydrogen sulfide and filtered again. The final solution was evaporated to dryness and 50 ml. of absolute alcohol added. The cloudy solution was placed in the refrigerator. The next day il slightly yellow crystalline material was removed and immediately recrystallized from water-isopropyl alcohol. -1crystalline material, 0.46 g. (10.3% yield of serine), m.p. 17.5275' dec., was thus obtained. The material was again rccrystallized from water-isopropyl alcohol. -1paper chromatogram using the phenol-water system with a n authentic sample of serine showed the material to be predominantly serine with only a trace of some other material which also gave a ninhydrin test. CORVALLIS, ORECOX
DEPARTMENT OF CHEMISTRY ASD CHEMICAL ENGIXEERING OF
THE
UNIVERSITY OF CALIFORMA
Substitution of Polynuclear Aromatic Compounds. I. The Friedel-Crafts Benzoylation of Naphthalene BY FREDERICK R. JENSEN RECEIVED JULY 30, 1956 Excess benzoyl chloride added t o the reaction mixture does not change the rate of the aluminum chloride-catalyzed benzoylation of toluene or p-xylene or the amount of ortho isomer (9.7%) formed in the reaction with toluene. In the reaction with naphthalene, the addition of excess benzoyl chloride t o the reaction mixture causes a large decrease in the rate of reaction and a n increase in the amount of @-ketone(less hindered) formed, It has beqn suggested previously t h a t the change in isomer distribution in the reaction with naphthalene is due to the excess benzoyl chloride complexing with the attacking group t o form a more bulky group. T h e results indicate t h a t this postulate can be true only if the attacking groups are different in the reactions with toluene (and @-xylene)a n d naphthalene. It is shown t h a t rearrangement is not responsible for the differences in isomer distribution.
Introduction In 1886, Claw and Feistl reported that the aketone is exclusively formed in the Friedel-Craf ts acetylation of naphthalene. Ten years later Rousset2 reported that both the CY- and /3-isomers are formed. Since that time the isomer distribution in this reaction has been investigated by numerous (1) A. Claus and P. Feist, B e y . , 19, 2896 (1886). (2) L. Rousset, Bzdi. SOC. chim.. 15, 58 (1896).
workers, but many of the results are confusing and ~ o n t r a d i c t i n g . ~I t is now recognized that the addition of a variety of substances, which complex strongly with aluminum chloride, to the reaction (3) An excellent review of the experimental work is given in t h e A.C.S. Monograph, C. A. Thomas, "Anhydrous Aluminum Chloride 1941, in Organic Chemistry." Reinhold Publ. Corp., N e w York. N. Y., p . 271. Reviews are also given by G. Lock, Monafsh., 74, 77 (19431, and by H. F. Bassilios, S. 11,Makar and A, Y.Salem, Ball. SOL, chim.. 72 (1954).
March 5 , 1957
FRIEDEL-CRAFTS BENZOYLATION OF NAPHTHALENE
1227
These results were further checked by withmixture, or their use as solvent, results in a decrease of the amount of a-isomer f ~ r m e d . ~ Jdrawing samples from a reaction mixture a t differTypical compounds that have been used are nitro- ent lengths of time, using nitrobenzene as solvent. With initial naphthalene and benzoyl chloridebenzene and excess acid halide. I t was first suggested by Fieser5that these added aluminum chloride complex concentrations 1.1 M , substances complex strongly with the attacking the product a t 35' was 32 f 1% P-ketone after 2 species making a bulkier attacking group, and hence min., 16 min. and 46 hours with yields 71, 82 and by a steiic effect, more of the less hindered isomer 9470, respectively. These results indicate that (@-isomer) results. I n the present work this hy- isomerization is negligible during an actual reaction. Isomerization of hindered aromatic ketones pothesis was tested by studying the effect of adding these substances on the absolute rates of reaction occurs if the ketones are melted with excess alumiin hindered and non-hindered positions of naph- num chloride and sodium chloride.? Effect of Excess Benzoyl Chloride in the Reacthalene and benzene derivatives. If a steric effect is responsible for the differences, the rate of reac- tions with Toluene, $-Xylene and Naphthalene.tion should also be affected by the addition of these The steric hindrance in the ortho position of toluene compounds. Also, the possibility that the differ- and the a-position of naphthalene are probably of ences result from rearrangement was investigated. the same order of magnitude. Any effects due to Benzoyl chloride was selected as the acid chlo- complexing of excess benzoyl chloride with the atride since a convenient method is available for de- tacking group would be expected to appear in the termining its concentration during the course of a reactions with either hydrocarbon provided the Friedel-Crafts reaction.6 Conditions were selected mechanisms of the reactions with the two hydrounder which the reaction mixtures are homo- carbons are the same. The formation of a bulkier geneous a t all times. Benzoyl chloride was also complex would cause the rate of reaction to decrease selected as the added agent because its concentra- in all positions but more in hindered positions. tion is known to affect the isomer distribution in the The effect was investigated first with toluene since reaction with naphthalene, i t can be conveniently it is a simpler compound than naphthalene. removed from the reaction mixture and in order In non-polar solvents, and for individual experito keep the system as simple as possible. If ments, the Friedel-Crafts reaction follows secondnitrobenzene were used, the situation might be order kinetics according to expression 1, where greatly complicated since i t is probably more basic Ar-H may be one of a variety of benzene derivathan benzoyl chloride and would preferentially tives. complex with the aluminum chloride. Under rate = kl [ CBHBCOCI :AlCla] [ Ar-HI (1) these conditions, the kinetics of the reaction would However, the value of k z depends on the initial be much more complex. concentration of the complex.*-12 For the reaction with toluene and using ethylene Results and Discussion chloride as solvent, second-order kinetics were Attempts to Rearrange a-Naphthyl Phenyl obtained according to expression 1, with kz deKetone.-The solubilities of Friedel-Crafts com- pendent on the initial concentration of the complexes are greater in more polar solvents. Since plex but independent of the toluene concentration. less of the a-isomer is obtained in polar solvents, When excess benzoyl chloride was added to the the differences in isomer distribution might be due reaction mixture, the value of k z and the amount of to isomerization of the a-ketone under conditions ortho isomerI3remained constant (Table I). These where the product remains in solution. results clearly indicate that the excess benzoyl It was found that a-naphthyl phenyl ketone does chloride does not combine t o an appreciable extent not isomerize under conditions more severe than with the attacking group to form a more bulky usually used in this reaction. The experiments complex. were carried out only under conditions where deA more sensitive compound with which to study composition does not occur. a-Naphthyl phenyl the effect is $-xylene, since all the positions are hinketone was recovered unchanged from a 0.6 M dered. The value of kz obtained in the absence of solution of its 1:1 complex with aluminum chloride excess benzoyl chloride was 2.05 X 1. mole-' in nitrobenzene (saturated with hydrogen chlo- sec. and with excess benzoyl chloride concentraride) a t 35' after one week. Similarly no isomeri(7) G. Baddeley and A. G. Pendleton, J . Chem. Soc., 807 (1952). zation took place after heating the 1:l complex (8) B . D . Steel, ibid., 1470 (1903). (0.634 M) in ethylene chloride (saturated with hy(9) S. C. J. Olivier, Rec. tvau. chim., 37, 205 (1918). drogen chloride and sealed in ampoules) a t 50' for (10) L. F . Martin, P . Pizzolate and L. S. McWaters, Jr., THIS 30 days. The recovery from the nitrobenzene solu- JOURNAL, 67, 2584 (1935). (11) H . Ulich and P . V. Fragstein, Bev., '72, 620 (1939). tions was 96-98y0 and quantitative from the ethylRecently F. Smeets and J. Verhulst, B i d . SOC. chim. belg., 63, ene chloride solutions. The infrared spectra of the 439(12)(1954), reported that k is essentially independent of the concenrecovered and starting ketones were identical, and tration of the complex at 35' when Ar-H is benzene (solvent). These the isomerization was less than 2y0 (experimental results are not consistent with the results reported earlier by Oliviero for the same reaction at 30°, and although we have been able to reproerror). ( 4 ) (a) M. Chopin, Bull.
SOC.Chim., 36, 610 (1924); (b) G.
Baddeley, J . Chem. Soc., S-99 (1949). For other references see the review articles given in ref. 3. ( 5 ) L. F . Fieser, "The Chemistry of Natural Products Related to Phenanthrene," Reinhold Publ. Corp., New York, N . Y., 1936, p. 74. (6) F. R. Jensen, P h . D . Thesis, Purdue University, 1955.
duce Olivier's results, we have not been able to reproduce the results of Smeets and Verhulst. Smeets and Verhulst followed the reaction by titrating the evolved hydrogen chloride, while in Olivier's and in the present work, the reactions were followed by determining the rate of disappearance of benzoyl chloride. (13) Unless otherwise indicated, the yields in all reactions were above 98%.
1228
FREDERICK R. JENSEN
TABLE I DATASHOX'ING TIiAT A b D E D BENZOYL CHLORIDE DOES S O T COMBISE IVITH THE ATTACKING SPECIES TO F O R M A BCLKIER COMPLEX I N THE REACTIOC IVITIT TOLCENE Solvent, CH2C1CH2Cl; temp., 25'; [C8H5CH3] = [C61-T5COCl:AlClB] 0.222 JI IC6HsCOC11, .W yGO V l i l O l 0 J k r (1. mole-1 sec.-l," 0 8.4 1.12 0 ,050 9.7 1 .08 .lo0 10.2 1 .09 .222 9.6 1.11 .450 10.1 1.12 ,827 9.4 1.65 10.3 3.31 9.0 a The average reproducibility of the rate constants was 3577.
Vol. 79
The addition of a small amount of benzoyl chloride causes relatively large changes in the amount of 8-ketone formed and the rate constant ( k 3 ) . This is probably the most striking feature of the results. With progressively larger amounts of ben7oyl chloride, the changes become smaller until the values become essentially constant. The results indicate that k3 does not vary in a simple fashion as the benzoyl chloride concentration is changed. T n the reaction with toluene the results were easily reproducible to within 37*. This is not the case with naphthalene, however, and the results ale very sensitive to the presence of impurities. For example, with a standard solution of the complex, CsH&OCl: A1Cl3, in ethylene chloride which was slightly colored, the rate constant in the reaction with toluene was identical with that obtained previously, while the rate constant in the reaction with tion 0.273 M the value of kz obtained was 2.16 X 1. mole-' sec.-l (ethylene chloride as solvent, naphthalene was about 15y0 less than that obtemp. 25", and with initial concentrations of the tained with colorless standard solutions. Any complex and +xylene 0.222 M). Since the ad- trace of impurity which complexes strongly with dition of excess benzoyl chloride does not decrease aluminum chloride would be expected to free benthe rate of reaction, the excess benzoyl chloride zoyl chloride from the complex, C6H5COC1: .41c13, must complex with the attacking group in this re- and the effect would be the same as adding a very small amount of benzoyl chloride to the reaction action to a negligible extent. It is known that excess benzoyl chloride affects mixture. The rate constants for the reaction in the a-posithe isomer distribution in the reaction with naphthalene.4b The effects of adding benzoyl chloride tions (k,) and P-positions ( k p ) are listed in Table on the rate of reaction and isomer distribution were 11. According to the data k, and kp both decrease when excess benzoyl chloride is present. studied in detail. The decrease in ks is small and was always obUnexpectedly, the reaction with naphthalene served in a number of experiments. Because the rate = k~[C8HjCOCl:AIC13] 2[CloH8] (2) system is very sensitive to impurities, i t is difficult was found to follow third-order kinetics.I4 The to place absolute limits of error on these values. value of k3 is not entirely independent of the initial The results with naphthalene are in accord with concentration of the complex. If excess benzoyl the postulate that the excess benzoyl chloride chloride is present, k3 decreases markedly and the complexes with the attacking group but are not amount of the less hindered P-ketone13 increases in proof since there are several other reasonable exthe manner shown in Table 11. planations for the results. (Investigations are currently being carried out along several lines.) TABLE I1 The results with toluene and @-xyleneclearly indiTHE EFFECTOF ADDISG EXCESSBENZOYL CHLORIDEO N cate that the excess benzoyl chloride does not comTHE ISOMER DISTRIBUTIOS AND THE RATEO F BENZOYLATIONplex with the attacking group in these reactions. OF XAPHTHALENE Therefore, ;f the postulate i s correct, the attacking Solvent, CH2CICH2C1; temp., 2.5'; [C6H6COCl:A1Clp]= groufir mast be d { f e w n t in the reactions with toluene [ClaH8] = 0.222 AW (and +xylene) and naphthalene. There is no direct [CbHsCOC1], M &: @-ketone lOkP 10Zk,b 10lkgC evidence indicating whether or not the attacking 0 20 3.6 2.9 0.72 groups are the same; however, in the absence of 0,050 27 2.5 1.8 .67 any evidence, it would seem to be more reasonable .lo0 30 2.2 1.5 .66 to expect the attacking groups to be the same. .222 34 1.9 1.3 .63 The results indicate that there are differences in ,300 36 1.7 1.1 .61 the details of the mechanisms of the reactions, but ,400 38 1.6 1 .(I .G1 the differences could be a t various stages in the re.82 40 actions. Although the kinetic orders are different 1.65 43 for the reactions with toluene and naphthalene, 3.66 43 this does not necessarily imply that the attacking mole-2 sec.-I. * k , = k3 X 7, a-ketone. kp = groups are different in the two reactions since the k3 X 7 0 0-ketone. details of the reactions may differ after the attacking group and aromatic compound have come to(14) The change in k2 with concentration in the reaction with toluene i n non-polar solvents can be rationalized on the hasis that there are gether to form the r-complex. Also, there is eviseveral terms in the rate expression, one of which is a third-order dence that the difference in the kinetic order may term, and t h a t these reactions are subject to general acid catalysis be due to the complexiry of the kinetics.14 by Lewis acids.6 A possible explanation for the apparent difference in kinetic order obtained in the reactions with toluene and naphthalene One possible explanation for the results is that is that the second-order terms predominate in the reaction with toluene the ability of various positions in polynuclear aroa i d the third order term predominates in the reaction with naphthamatic compounds to bear a positive charge varies lene. The results of a detailed study of this and related reactions will greatly with the environment, and hence the relabe reported later,
March 5 , 1937
FRIEDEL-CRAFTS BENZOYLATION OF NAPHTHALENE
tive reactivities of the various positions may not be a function of structure alone. Jn the present case this may be the result of a difference of stabilization of the a-complexes in the a- and 0-positions by the polar benzoyl chloride molecules. There are no data available which indicate whether the effects studied are unique to the Friedel-Crafts reaction or are general for electrophilic substitution of naphthalene. Relationship between the Concentration of the Complex and the Isomer Distributions.-The problem is complicated by the finding that the isomer distributions in the reactions with both naphthalene and toluene depend on the initial concentration of the complex (Table TII).13 If the naphthalene concentration is greater than the concentration of the complex, the isomer distribution is independent of the naphthalene concentration (Tables 111and V). TABLE I11 EFFECTOF THE COSCENTRATION OF THE COMPLEX ON THE ISOMER DISTRIBUTIONS I N THE REACTIONS WITH NAPHTHALENE AND
TOLUENE [ C B H ~ C H=~[CloHs] ] =
Solvent, CH&lCH2Cl; temp., 25'; 0.222 M lCaHaCOC1 :AlCL,I M
0.0500
,100 ,222 ,400 ,500 1 95
% @-Ketone
35 32 20 10 10
ICsHsCOC1:AIClsJ, M
0.05 .10 ,222 .60
yo ortho
7 8.1 9.4 11.7
7
Since the rate constants in the reactions with naphthalene and toluene depend on the initial concentration of the complex, i t is not unexpected that the isomer distributions also depend on its concentration. The data for naphthalene in Table I11 suggest one reason for the contradictory results obtained by previous workers. The isomer distribution will be appreciably different depending on whether the naphthalene is added to the complex or vice versa. Also, if the complex is added t o the naphthalene, it is predicted that the isomer distribution will depend on the rate of addition. It is hoped that a system can be found in which the above complication does not exist. Investigation of the Possibility that the Varying Isomer Distribution May Be Due to Complex Formation between Naphthalene and Benzoyl Chloride.-One possible explanation for the results is that the excess benzoyl chloride forms a stable complex with naphthalene, and the reaction is forced to take place with this adduct. There is no report in the literature of complex formation between naphthalene and benzoyl chloride, but there is evidence which indicates that nitrobenzene, which causes a similar change of the isomer distribution, and naphthalene form an addition compound.16 The above explanation was tested in a simple fashion. If the proposed explanation is correct, the amount of P-ketone formed should depend on the relative concentrations of the excess benzoyl (15) G. Briegleb and J. Kambeitz, 2. phyrik. Chcm., B26, 253 (1934).
1229
chloride and naphthalene. At high naphthalene concentrations and low benzoyl chloride concentrations, the isomer distribution should be essentially the same as in the absence of benzoyl chloride since the reaction would take place almost entirely with uncomplexed naphthalene. In testing this hypothesis i t is necessary that the initial concentration of the complex, CsHsCOC1 :AICIJ, is kept constant and that the same amount of complex reacts in each experiment. This was accomplished by using a low concentration of the benzoyl chloride-alu. minum chloride addition compound and always having it as the limiting reagent. The results are in Table I V and show that the TABLE IV EFFECTO N THE ISOMERDISTRIBUTION OF CHANGING THE CONCENTRATION OF EXCESS BESZOYL CHLORIDE AT VARIOUS SAPHTHALENE CONCENTRATIOXS Solvent, CH2ClCHZC1; temp., 25" ; [ CBH,COC~ :AlCla] = 0 224 M ; the yields were greater than 9570 in all reactions [CioHsj, M
[CeHsCOCI], M
0.224 ,224 .224 ,224 450 ,450 ,450 ,450 1.35 1.35 1.35 1.35
0 0.10 .40 1.20 0 0.10 .40 1.20 0 0.1
I
.4
1.20
70 ,%ketone 20 29 38 43 20 28 38 40 20 24 36 39
explanation which was proposed above is incorrect. If a stable adduct is formed between the benzoyl chloride and naphthalene and if the formation of this adduct is responsible for the differences in the isomer distribution, then it should be possible to calculate maximum possible values for the amount of @-ketoneformed a t various benzoyl chloride concentrations. Typical calculations are given in the next paragraph. From the data in Table I1 and under the hypotheses assumed above, i t is seen that if all the naphthalene is complexed with benzoyl chloride, the maximum amount of 0-ketone formed is 43%, and if none is complexed, the amount of P-ketone formed is 20%. In the experiments (Table IV) in which the initial naphthalene concentration was 1.35 M , the concentration of the naphthalene was always greater than 1.12 M . For benzoyl chloride concentrations of 0.1 and 0.4 M , the amounts of free naphthalene (uncomplexed with benzoyl chloride) would be more than 1.02 and 0.72 M , respectively, a t all times during the reactions. Then assuming that the reaction with the naphthalene-benzoyl chloride complex is one-half that with the free naphthalene (from the data in Table I1 it is seen to be less than one-half), i t is calculated that less than 21 and 24% of the @ketone would be formed at benzoyl chloride concentrations 0.1 and 0.4 M , respectively. Since the amounts of P-ketone formed exceed these values, the postulate must be invalid. The yields in the reactions with high naphthalene concentrations were 95-96%. The excess naph-
FREDERICK R. JENSEN
1230
Yol. 79
weigh and transfer them without bringing them into conTABLE Y tact with air. Only samples of aluminum chloride which I)ATA SHOWING THE RELATIOXSHIP BETWEES THE RELATIVE were entirely colorless and crystalline were used in the csBESZOYLCHLORIDEAND AT^^^^^^^^^^ COXCENTRATIONSperiments. ASD THE ISOMER DISTRIBUTIOSAT HIGH CONCESTRATIOXS Naphthalene.-The naphthalene was purified by distillation and then six recrystallizations from ethanol. OF THE COMPLEX Ketone Standard Samples.-The standard samples merc Solvent, CH2CICH2C1; temp., 25' prepared by treating the corresponding methylbenzol-1 chloiCsHsCOC1:[CeHsCOCI], ride or naphthoyl chloride with benzene using aluminum AICls]. .L1 J C ~ O H Id.I I, .\.I (2 8-ketone chloride as the catalyst. The compounds were purified by 1.95 0,100 ci 7 recrystallization from ethanol. T h e o-tolyl phenyl ketone was recrystallized a t l o x temperature, since it melts below 1.95 .loo 6 8 room temperature. 1.95 . ioo 6 8 T h e solid ketones had t h e following melting points (cor.): 1.95 ,100 (9 8) a-naphthyl phenyl ketone, m.p. 75.4-75.9' (1it.j m . p . 1.95 ,250 6G 75.5"); p-naphthyl pilenyl ketone, m.p. 82.0-82.3" (lit.5 m.p. 82.0") and p-methylbenzophenone, m.p. 55.8-56.6'. 1.95 ,250 69 T h e infrared spectrum of the liquid o-methylbenzophenone 1 .9.i ,250 7 7 was identical with t h a t of the pure isomer.16 1.95 2SO 10 '3 Ethylene Chloride.-Commercial ethylene chloride was 1.95 GI I 9 8 shaken with portions of technical grade fuming sulfuric acid until darkening no longer occurred. The chloride was 1.95 Gi 1 10 6 washed with water and allowed t o stand over F a O H pellets 1 .95 , 61) 11 2 for several days. Finally, it was fractionated twice from 1.95 GO 13 8 CaHz through a 44" vacuum jacketed column (i.d. 21 IIIIII.), 1 ,711 1.03 which was packed with 3/16'' diam. glass helices. The mate10 6 rial boiled at a constant temperature (b.p. 83.3" ( 7 5 2 mm.) 1.70 1,113 12 3 uncor.). The reflux ratio was greater than 2 5 : l . Some 1 .7o 1 ,113 14 8 of t h e material was heated over t h e CaH? at total reflux for 1 ,711 1 . o:? 21 3 1 days. No detectable temperature drop occurred, which indicates CaH2 docs not dehydrohalogenate ethylene chlothalene was removed from the ketone by steam dis- ride under these conditinns. Infrared Analysis.-The isomer distributions were detillation, and some of the ketone was lost in this termined by infrared analysis using a Baird Associates operation. double beam recording spectrophotometer. The analyses The first attempts to detect a relationship be- were carried out using 0.1 mm. matched S a c 1 cells and CS? tween the relative benzoyl chloride and naph- as solvent. For each separate series of experiments, fresh thalene concentrations and the isomer distribution solutions of the standard samples w r e prepared and new plots of log l o / l as. concentration were made over the eonwere carried out a t high concentrations of the com- centration range encountered in t h e experiments (total conplex, CGH,COCI:-4lCl3. These experiments failed centration, about 0.25 g . ketones/5 ml. CS2solution). In the reaction r i t h toluene, only the o r t h o and par(i because the isomer distribution depends on the amount of complex, C6H,COC1: AlC13, reacted. isomers were determined. T h e mctn isomer, which i i charby a peak a t 8.3 p,le was present t o the extent of 1 The resultsI3 are shown in Table V and are interest- acterized 2yo in all experiments. Over a period of three months and ing because a t high concentrations of the complex, for a large number of experiments, 4
