1225
Ndk?$
A department for short papers of immediate interest.
organic product was found to be itself thermally labile, a flash pyrolytic technique was developed to permit its isolation. A solution of I1 in dry carbon PHILIP EATON,* EMERY CARL SON,^ PASQUA1.E LOMBARD0,3 AND P E T E R YATES' tetrachloride was dropped slowly onto the top of a column of ceramic saddles held in a vertical Received December 28, 1959 Vycor tube heated by a concentric furnace to 475500'. The tube was flushed continuously with a rapid Hexachlorocyclopentadiene gives on reaction stream of dry, oxygen-free, nitrogen. With this with aluminum chloride a dimeric chlorocarbon, apparatus it was possible to effect the pyrolysis m.p. 485°74-6and with liquid sulfur trioxide a re- and remove the product from the heated zone within lated chloroketone, m.p. 350°.6 The structures approximately ten seconds. The solvent and prodI and I1 postulated by McBee7for these compounds uct were condensed in an ice trap placed immedihave recently been corroborated by physical ately below the heated tube. Chromatography of the methods, comprising dipole infrareds crude product gave a white crystalline material, and x-ray'" measurements. Their unusual chemical C9Cls7m.p. 138-139', in 80% yield and unchanged inertness has led us to investigate their thermal I1 ; hexachlorobenzene, arising from pyrolysis of stabilities and behavior on pyrolysis. the carbon tetrachloride, was also isolated. Only trace amounts of hexachlorocyclopentadiene were detected, in contradistinction to the observations of Idol1' who pyrolyzed I1 under conditions which could lead to the decomposition of the initially formed product. Little or no carbonaceous material was produced; the yield of the CeC& product corrected for recovered I1 was 90-95a/, in the several pyrolyses carried out. For comparison purposes, I was treated in a similar fashion. At 500' only slight pyrolysis occurred giving trace amounts of hexaIt has been reported7." that the chlorocarbon chlorocyclopentadiene; no carbonaceous material I is remarkably stable to heat, substantial pyrolytic was formed. fission occurring only on prolonged heating a t or The pyrolysis product from I1 was shown to be above 500 ' to produce largely carbonaceous ma- octachloroindene, 111,by comparison with a sample, terial and chlorine together with a small amount m.p. 138-138.5", prepared by the reaction of of hexachlorocyclopentadiene. phosphorus pentachloride with hexachloroindone The thermal stability of the cage system is how- (IV), itself prepared by the action of aqueous ever markedly reduced by the introduction of the acetone on octachloro - 3a,4,7,7a - tetrahydrocarbonyl group in 11.We find that molar equivalents 4,7-methanoindene-1 ,&dione (V) .12 The preparaof carbon monoxide and chlorine are readily elimi- tion of octachlorindene by this method has been nated a t temperatures above 450'. Since the initial reported previously by Zincke and Gunther,13 (1) Compound 11, decachloropentacyclo[5.3.0.02~~.04~1@. who gave its melting point as 84'; a subsequent O"g]decan-3-one, alternatively named decachloroocta- report in the patent literature14 has, however, hydro-l,3,4-methe1io-2H-cyclobuta[cd]-pentalen-Z-one; cf. given a melting point of 132'. Because of this disH. E. Ungnade and E. T. McBee, Chem. Revs., 58,249(1958). crepancy it was considered essential to establish (2) Harvard University. the structure of the pyrolysis product independ(3) .4llied Chemical Corporation. (4) H. J. Prins, Rec. trav. chim., 65,455 (1946). ently. Reaction with liquid sulfur trioxide gave the (5) J. S.Newcomer and E. T. ?%Bee, J . Am. Chem. SOC., indone IV; chlorination gave a product C9Cllo,iden71,952(1049). (6) E.E.Gilbert and S. I,. Giolito, U. S.Reissue Patent tical with a sample of decachloroindane (VI) prepared by the destructive chlorination of naph24,435. ( 7 ) E. T. McBee, C. W. Roberts, J. D. Idol, Jr., and R. thalene in the presence of an iodine/iron catalyst.14 H.Earle, Jr., J . ilm. Chem. SOC.,7 8 , 1511 (1956). Treatment of this product with liquid sulfur tri(8) D. H. Zijp and H. Gerding, Rec. trav. chim., 7 7 , 682 oxide gave hexachloroindane-1,3-dione (VII) in (1958). (9) W. H.biears, General Chemical Research Laboratory, (12) T.Zincke and K. H. Meyer, Ann., 367,1(1909). private communication. Pyrolysis of the Cage Ketone Cl&lloO1
(10) R. Pepinsky and Y. Okaya, Dept. of Physics, Pennsylvania State University, private communication. (11) J. I). Idol, Jr., 1'h.D. Thesis, Purdue, 1954.
(13) T.Zincke and H. Gunther, Ann., 272,243 (1893). (14) H. Vollmann, Ger. Patent, 844,143 (1952); rf. Cheni. .Ibstr., 50, 4227 (1056).
12%
VOI,.
NOTES
25
EXPERIMENTAL'S
v
c1
I11
VI
so./
c1
c1
c1
Cl
c1 0 VI1
quantitative yield.I6 The diketone was readily oxidized by potassium permanganate to the well known tetrachlorophthalic acid. These reactions provide unambiguous confirmation for the formulation of the pyrolysis product as 111. By analogy with the observed fission of I, it might be considered that octachloroindene is formed from I1 by cleavage to hexachlorocyclopentadiene and tetrachlorocyclopentadienone, followed by a Diels-Alder recombination with hexachlorocyclopentadiene acting as the dienophile and subsequent decarbonylation and dechlorination. However, hexachlorocyclopentadiene has never been observed to act as a dienophile, while tetrachlorocyclopentadienone is known to undergo very ready dimerization t o VI6; neither V nor its pyrolysis products, octachloroindanone and ITJ, were detected among the products of the pyrolysis of I1 under the conditions here described. It seems more likely therefore that the pyrolysis reaction involves the initial loss of the carbonyl group of I1 as carbon monoxide followed by intramolecular rearrangement and aromatization by loss of chlorine. l7 (15) Cf. J. Bernimolin, Ber., 87, 640 (1954). (16) J. S. Newcomer and E. T. McBee, J . Am. Chern. Soc., 71,946 (1949). (17) It may be noted that I11 is more closely related to the unsymmetrical cage structure VIII; such a structure for the C~OC~OO ketone, however, appears to be ruled out.*-10 CI c1
Dodecachloropentacyclo[6.5.0.02~6.04~10.05~9] decane (I). The method of Newcomer and McBees was used. Repeated crystallization of the crude product from benzene gave white cubic crystals, m.p. ca. 485" (sealed capillary), showing no absorption in the infrared between 2 and 8.6 U . Decachloropentucyclo[5.3.0.02,fi.048 lo.O5,@] decun-%one (11). Crude material was obtained by the procedure of Gilbert and Giolito.6 Decolorization was effected by treatment of a methanolic solution with activated charcoal; addition of water to the filtered solution followed by a preliminary airdrying of the precipitated solid gave hydrated 11. Anhydrous material was prepared by prolonged refluxing of a xylene solution of the hydrate under a Dean-Stark water trap; on concentration, this solution deposited large white crystals of pure 11, m.p. ca. 350' (sealed capillary),
5.58 p. Pyrolysis of I and 11. Pyrolyses were run by permitting solutions in carbon tetrachloride (50 g./l.) to fall dropwise from a pressure-equalizing funnel onto the top of a 30-cm. column of Berl ceramic saddles held vertically within a Vycor tube, 2.8 cm. in diameter, and heated to 500" by a concentric furnace. The tube was flushed continuously with a rapid stream of dry, oxygen-free, nitrogen. Temperatures were measured by iron-constantan thermocouples contained within thin Vycor tubing, one located a t the packingliquid point of contact and the other a t the column center. A maxipum temperature difference of 100' between these points was maintained by adjusting the rate of addition of solution. Solvent and products were condensed in an ice trap placed immediately below the heated zone. Test runs indicated that hexachlorobenzene was produced by pyrolysis of the solvent (about 0.2% of solvent converted); it was possible to remove it entirely by volatilization on concentrating the condensates on the steam bath. The infrared spectrum of the condensate from the pyrolysis of I corresponded to that of unchanged starting material contaminated with small amounts of hexachlorocyclopentadiene; no carbonaceous material was formed. The condensate from the pyrolysis of I1 was concentrated to one tenth of its original volume (the distillate contained only hexachlorobenzene in addition to carbon tetrachloride) and was chromatographed on neutral alumina. Evaporation of the fraction obtained by elution with carbon tetrachloride gave white crystalline material, m.p. 13&139", in 80% yield, identical in all respects to octachloroindene; its melting point was undepressed on admixture with authentic material (vide infra). Subsequent elution with methanol gave a fraction which contained unchanged I1 as its methanol adduct. After correction for recovered starting material (about 15'%), the yield of octachloroindene ranged from 90-9570. The unpleasant odor of the concentrated condensates indicated the presence of trace amounts of hexachlorocyclopentadiene. Hexachlormndone (IV). Octachloro-3a,4,T,7a-tetrahydro4,7-methanoindenel,8-dione(V; 200 g.), prepared by sulfuric acid hydrolysis of 1,l-dimethoxytetrachlorocyclopentadiene,12 was dissolved in acetone (500 ml.). Water (ca. 350 ml.) was added rapidly to a slight cloudiness. The solution darkened immediately, and yellow crystals of IV separated after 5 min. After standing overnight, the mixture m-as filtered and the precipitate crrstallized from methanol to give 123 g. (82%) of bright yellow crystals, m.p. 149-150", 5.77, 6.37W . Bnul. Calcd. for C9ClsO: C1, 63.1. Found: C1, 63.1. Octachloroindene (V). A heavy-walled glass pressure bottle was charged with 5.6 g. of IV and 10 g. of phosphorus pentachloride. The mixture was heated in an oil bath under autog(18) Melting points are uncorrected. Ultraviolet spectra were recorded on a Cary Dual Beam Spectrometer. Infrared spectra were taken on a Perkin-Elmer Model 21 recording spectrometer.
enom pressure a t 190-205" for 2 hr. After cooling, water and ether/rtcetone were added to dissolve all the solids. The ethereal layer was separated, washed with water, dried over sodium sulfate, and diluted with methanol. Partial evaporation of this solution gave white needles (5 g., 79%) of octachloroindene, which were found to be very sensitive to light. The analytical sample, prepared by repeated crystallization from methanol, melted a t 138-138.5', KB, A,, 6.29 p, (E), 236 m.u (19,500), 242 mp (21,000), 250 mu (29,000), 259 m.u (31,000). Anal. Calcd. for CQc13: C, 27.59; C1, 72.41. Found: C, 27 52; C1,72 23. Chloiination of V ; decachloroindane (VI). Chlorine gas was bubbled through a solution of 5 g. of V in 75 ml. of carhon tetrachloride held a t 50" for 2 hr. Evaporation of the solvent and crystallization of the residue from methanol gave 4.8 g. (8170) of white crystalline material, m.p. 134135", identical with a sample of decachloroindane (VI) prepared bv 1he destructive chlorination of naphthalene as described by V0llmann.1~ Anal. Calcd. for CQCllo: C1, 76.64. Found: C1, 76.51. Hydrolysis of V; hexachloroindone (IV). Five grams of V were dissolved in 25 ml of liquid sulfur trioxide. The ewew sulfur trioxide was allowed to evaporate overnight from an open beaker. The remaining sulfiiric acid-solid mivture was washed with cold water, and the solid crystallized from methanol to give a nearly quantitative yield (4.4 n- . ) of IV, m.p. 149-1\50'. Hexachloroindane-1,s-dione (VII). Five grams of VI were treated \I-ith liauid sulfur trioxide in the same manner as above. A4cpant'itative yield (3.8 g.) of VI1 was obtained as bright yellow crystals, m.p. 155-156", k:2i4 5.65, 5.75 p. Anal. Calcd. for C9ClsO2: C1, 60.30. Found: C1, 60.28. This material was identical with a sample prepared by treatment of VI xvith anhvdrous nitric acid as descrihed hy Bernimolin. l5 Oxidutzori of VII. Three grams of potassium permanganate in 50 ml. of aqueous 570 sodium hydroxide was added with stirring to I g. of VI1 in 10 ml. of warm acetone. After 4 hr., the solution was acidified with coned. hydrochloric acid, bleached with sulfur dioxide, saturated with ammonium sulfate, and extracted with ether. The ethereal extract was washed with water and evaporated to dryness. Sublimation of the residue gave crystals of tetrachlorophthalic anhydride, m.p. 254-256', identical with an authentic sample. I
_
Acknouiledgment. The authors are indebted to Dr. Everett E. Gilbert for his advice and counsel.
proximately 15-membered ring give a musklike odor independent of the type of atoms in the ring skeleton was presented by Rueicka et aL2 However, in the syntheses of macrocyclic ureas3 and macrocyclic amide^,^ we found that they gave no odor. Because of the big intermolecular attractionpossibly by H-bonding of the compounds which contain urea- or amide-linkages, it is understood that the melting point becomes high and the volatility becomes low. Assuming that the absence of odor in the macrocyclic ureas and macrocyclic amides was due to their strong intermolecular attraction, we carried out the syntheses of macrocyclic N-alkyl amides and N,N'-dialkyl ureas in which there is no possibility of H-bonding. 2Methyl-2-azacyclohexadecanone was synthesized from 1,16-hexadecanedioic acid and was found to have a musklike odor. The sequence of reactions used is shown in Scheme I. In the reaction of the bromoester (11) with methylamine, N-methyl-15-methylaminopentadecanamide (111) rather than methyl 15methylaminopentadecanoate was obtained. 15Methylaminopentadecanoic acid (IT') was obtained by hydrolysis of 111 with alcoholic potassium hydroxide, followed by adjusting the pH of the solution to 8.0. Scheme I Brz
AgO,C( CH2)14C02CH~ + Br( CH2),JXhCHd I I1
KO H
CH3NH(CH2)irCOKHCHz
pH80
TI1 CHzNH( CHz)i4COzH IV
HC1
+
HCl.CHzi\jH( CH2)idCOzH V
DEPdRTMEST O F CHEMISTRY HARVARD UXIVERRITY CAMBRIDGE, MASS. GESER.41, CHEMICAL DIVISION
CHsNHa
___f
SOClz
+ (CzHd~h'
[HCl*CHJXH(CHZ)I~COC~I -+
c=o
CHI--S
-4LLIED (2HEMICAL CORP.
MORRISTOWN, N. J.
I
I
'-(CH~)I~~ VI
3Iacrocyclic Compounds. 2 -I\'lethyl-2-azacyclohexadecanone YOSHIO I W b K U R A AND
KEIKICHI UNO
Received October 1, 1969
Since the structure of natural musk was established as that of a macrocyclic ketone,l many macrocyclic compounds have been synthesized. An assuniption that cyclic compounds with an ap(1) L. Ruzicka, Helu. fhim. Acta, 9, 715, 1008 (1926).
When the hydrochloride (V) of the amino acid \vas treated with thionyl chloride, the amino acid chloride hydrochloride was apparently formed. 2-Methyl-2-azacyclohexadecanone (VI) was prepared by treating the reaction product of amino (2) L. Ruzicka, G. Salomon, and K. E. Meyer, Helu. Chim. Acta, 17, 882 (1934). (3) Y. Iwakura, K. Uno, and M. Nakada, J . Chem. SOC. J a p a n , 80, 78 (1959). ( 4 ) Presented a t the 12th meeting of the Chemical Society of Japan, Kyoto, April 1959.
1228
VOI,.
Noms
acid hydrochloride V and thionyl chloride with triethylamine in benzene under high dilution.
25
Diels-Alder Adducts of Hexachlorocyclopentadiene with Allyloxyalkanols
EXPERIMENTAL
Methyl 16--bromopatademnoate.6 Wet silver oxide was added t o molten methyl hydrogen 1,lGhexadecanedioate. The silver salt obtained was dried and dispersed in 200 mi. of dry carbon tetrachloride. To the dispersion bromine (82.5 g.) was added gradually while stirring a t 40' and the dtirring was continued for 2 more hr. a t the same temperature. The reaction mixture was filtered, the filtrate was washed with aqueous potassium carbonate and dried with calcium chloride. The solvent was removed and the residue was distilled under reduced pressure to give faint brownish crystals, yield 55 g., b.p. 180'/0.3 mm., m.p. 36-38'. N-Methyl-16-methylaminopentademnamide. Thirty-three g. of methyl 15-bromopentadecanoate was dissolved In 100 g. of 30% methylamine solution in methanol and the solution was allowed to stand for 5 days at 30". After the methanol and excess methylamine were removed, the residue was dissolved in ether. The ethereal solution was washed with aqueous potassium carbonate. The solvent wm removed and the residue was distilled under reduced pressure t o yield 18 g. of white crystals, h.p. 194-198"/0.05 mm., m.p. 78-79 O . Anal. Calcd. for Cl~HasONg:N, 9.85. Found: N,9.62. 15-Methylaminopentadecanoic acid. N-methyl-15-methylaminopentadecanamide (18 9.) was dissolved in a mixture of potassium hydroxide (15 g.), water (20 ml.), and methanol (80 ml.), and heated for 40 hr. under reflux After the methanol was removed, the residual alkaline solution was poured into 500 ml. of hot water and the pH of the solution was adjusted to 8.0 with 1N hydrochloric acid. The resulting precipitate weighed 8.3 g. and melted a t 132-135'. Recrystallization from 50% ethanol solution gave white leaflets, m.p. 142.5-143.5'. Anal. Calcd. for Cl6HaaO2N: N, 5.16. Found: N, 5 08. 16-Methylaminopentadecanoic acid hydrochloride. 15-Methylaminopentadecanoic acid was dissolved in hydrochloric acid and excess hydrochloric acid was removed under reduced pressure. Recrystallization of the residue from 9076 acetone solution gave white leaflets, m.p. 127-128'. Anal. Calcd. for C16H?a02NCl:C1, 11.52. Found: C1, 11.55. 8-Methyl-8-azacyclohexadecanone. 15-Methylaminopentadecanoic acid hydrochloride (4.4 g.) was dissolved in 20 ml. of thionyl chloride. The excess thionyl chloride was removed under reduced pressure and the residue was dissolved in 50 ml. of absolute tetrahydrofuran. The solution was added to a mixture of triethylamine (35 g.) and dry benzene (3000 ml.) and then stirred a t 75" for 15 hr. The reaction mixture was concentrated to about 1000 ml., washed with aqueous potassium carbonate, and the solvent was removed under reduced pressure. The residue was extracted with n-hexane, the extract was washed with aqueous sodium hydroxide, and the solvent was distilled. Distillation of the residue gave tl clear colorless oil, 1.3 g., b.p. 150-168"/2 mm. Redibtilled sample for analysis gave the following values: b.p. 172"/2.5 mm., n3: 1.4895, d:' 0.9782. Anal. Calcd. for CleHalON:N, 5.53. Found: N, 5.49. Molecular weight. Calcd. for CISH~ON:253. Found: 251. Molecular refraction. Calcd. for C16Ha10N: 77.759. Found: 77.234. RESEARCH LABORATORY OF RESOURCES UTILIZATION TOKYO INSTITUTE OF TECHNOLOGY MEOUROKU, TOKYO, JAPAN (5) P. Chiut and J . Hausser, HeZu. Chini. Actn, 12, 463 ( 1929).
CARLETON W. ROBERTSA N D DANIELH. HAICH Received February 2, 1960
Many Diels-Alder adducts of hexachlorocyclopentadiene have been reported"2 with most classes of dienophiles. Of these adducts there have been a number with reported biological activity. I n the field of agricultural chemistry one of the pressing weed control problems is that of aquatic plant life; the destruction of bothersome aquatic plants is particularly important in drainage and other service ditches. Hexachlorocyclopentadiene itself has shown some activity as an aquatic herbicide3; it has, however, the disadvantages of low water solubility and relatively high toxicity. Simple Diels-Alder adducts of hexachlorocyclopentadiene have been prepared from olefins possessing water solubilizing groups and these have as a rule been less toxic than the parent diene. For example, adducts have been prepared from allyl glycidyl ether4 and from divinyl ether5; sulfite derivatives have been prepared from the adduct with 2-butyne1,4-dioL6 As a rule these have biological activity and possess greater water solubility than hexachlorocyclopentadiene itself. This report describes the preparation of a series of adducts of hexachlorocyclopentadiene with dienophiles which might display enhanced water compatibility while at the same time retaining herbicidal activity. A series of allyloxy derivatives was prepared from allyl alcohol with ethylene oxide, 1-butylene oxide, and styrene oxide. These compounds (see Table 1) were utilized in a standard preparative procedure with hexachlorocyclopentadiene to obtain the Diels-Alder adducts (see Table 11). Purified samples of the compounds were tested against the several organisms. It is interesting that the adducts from 2-allyloxyethanol, 2(allyloxyethoxy)ethanol, and 1-allyloxy-2-butanol were reasonably soluble or emulsifiable in water whereas the adduct from 2-allyloxy-1-phenylethanol was only slightly soluble; the biological activity of the first three adducts against both water weeds and other test organisms is of interest. The 2-allyloxyethanol and 2-(allyloxyethoxy)ethanol adducts both show pronounced activity as insecticides and herbicides as well as inhibition in micro(1) C. W. Roberts, Chem. & Znd. (London), 110 (1958). (2) H. E. Ungnade and E. T. AlcBee, Chem. Reus., 58, 249 (1958). (3) Personal communication, Dr. K. Leasure, The Dow Chemical Company. (4) W. L. Bressler and J. C. Smith, U. S. Patent, 2,834,790 (May 13,1958). (5) A. Goldman, U. S. Patent 2,795,619 (Jiine 11, 1957). (6) British Patent 810,602 (March 18, 1959).
JULY
l(360
1229
NOTES
TABLE I
ALLYLOXYALKANOLS CH~=CHCHIOR Substituent R
B.P."
mm.
56
10
1.4326
106 95 125
10 GO
1.4445 1.4312 1 5193
CHzCH20I-I (CHzCH20)2II CHZCHOHC2Hs CHzCH( C6Hj)OW
B.P."
n2:
10
Literature Values mni.
atm 20 2 ... 4 5
159-160 58-60 98-101
..
1 18-1 19
nD
1.4355(20)' 1.4360(20)b 1 4440(20)a
..
c
1 5167(30)d
' A. A. Berlin, A. K. Duhagova, and E. F. Rodionova, Sbornik Statei Obshchei Khim, 2, 1560 (1953);Chem. Abstr., 49, 5388 (1955). .'1 N. Kotreelrv and I. K . Rubstova, K h i m Prom., 1953,8 ; Chem. Abslr., 50,(5384 (1956). Anal. Calcd. for C,HI4O2:(I, 64.59;H, 10.84.Found: C, 63.91;H, 10.35. D. Swcrn, G. pu'. Billen, and H. B. Knight, J . Am. Chem. Soc., 71, 1152 (1949). TABLE I1 ( 1, ~,5,GJ7,7-HEXACIILOROBICYCL0 [2.2.1]-5-HEPT&N-2-YL)MET110XYALKANOLba
[email protected] C1
c1 Yield,
a
Substituent R
%
OCH2CHtOH O(CH&HtO)zH OCH2CHOHCZHs OCH&H(CaHs)OH
72 75 62 42
B.P." mm
167 185 164 250
0.3 0.2 0.2 0.8
n2: 1.5446 1.5335 1.5319 1.5673
Carbon Calcd. Found
32.03 34.40 35.76 42.61
31.75 34.29 36.21 41.97
Hydrogen Calcd. Found
2.69 3.37 3.50 3.13
2.51 3.43 3.49 3.37
Chlorine Calcd. Found
56.74 57.40 50.78 50.55 52.79 52.80 47.17 47.60
Elemental analyses by Dr. S. A. Shrader, Analytical Laboratories, The Dow Chemical Co., Midland, Mich.
biological screening against S. aureus whereas the 2-allyloxy-1-phenylethanoladduct shows little or no activity in any of the three latter tests.
Synthesis of 3,5-Diphenylpheilol and a Novel Complex Thereof ])AVID
R.
SEXSMITH A N D JOHN
€1. 1tASSn EILER
EXPERIMETU'TAL
Recezved December 23, 1953 Typical preparative details are given for oiily one cspcriment; the other compounds were prepared under nearly In the course of a synthetic scheme it was necesidentical conditions (Tables I and 11). Preparation of (2-(I, ~,~,6,7,7-hexachlorobicyclo[2.2.1]-5sary to prepare 3,5-diphenylphenol. 3,s-Diphenylhepten-~-'-yl)metho2yeetho~y)ethanol.A mixture of 146 g. (1 phenol (111) has been prepared by dehydrogenamole) of 2-(2-allyloxyethoxy)ethanol (see Table I for phys- tion of 3,5-dipheny1-2-cyclohexen-l-one1 (I), by ical data on starting compounds), 272 g. (1 mole) of hexachlorocyclopentadiene and 500 ml. of o-xylene was placed decarboxylation of 4,6-diphenylsalicylic acid,* and in a 2-l., single-necked, round-bottomed flask equipped with by decarboxylation of 2,6-dicarboxy-3J5-diphenY1a reflux condenser and heating mantle. The mixture was phen01.~In all cases, the yields were too small to heated t o reflux and maintained a t a temperature of 144' be satisfactory in a synthetic scheme. It was refor 20 hr. The mixture was distilled to remove xylene and ported that bromination of I lvith bromine folunchanged starting materials and to isolate the pure IXels to give 'I1.' Alder adduct, ie., (2-( 1,4,5,6,7,7-hexachlorobicyclo[2.2.1.]-lowed by dehydrobromination 5-hepten-2-y1)methoxyethoxy)ethanol (315 g., 750/,), b 1) It was felt that repeating the p~eparationusing 185"/0.2mm., n y 1.5335.
POLYBIER RESEARCH L ~BORATORY TaE DoW CHIXWCAI, co. MII)LAND, Rlic~i.
(1) A. D. Petrow, Ber.. 62,642(1929). (2) J. Kenner and H Shaw, J. Chenz. Soc., 769 (1931). (3) W.I)euschpl, Helv. Chim. Acta. 34, 168 (1951).
N-bromosuccinimide as the brominating agent might be more successful, as Deuschel reports that bromination of diethyl 2-oxo-4,6-diphenyl-6-cyclohexene-1,3-dicarboxylatewith N-bromosuccinimide gives the corresponding phenol in excellent yield.
+ RvR NBS
I
R =I0 phenvl
itI1
tRVR bH
for recovered ketone. The recovered starting material from the complex may be recycled without further purification. Apparently the spontaneous dehydrobromination begins when the bromination approaches 40-50% completion and the evolved hydrogen bromide halts further bromination. To circumvent this problem and increase the yield of 111, large excesses of N-bromosuccinimide and peroxide catalyst were used. In these cases, the overall yield of I1 was reduced from 90% to 7080% and some excess phenol was produced.
111
3,5 - Diphenyl - 2 - cyclohexen - 1 - one was prepared by the condensation of benzalacetophenone and acetoacetic ester, followed by hydrolysis and decarb~xylation.~ Bromination was readily effected with N-bromosuccinimide and the bromo-3,5diphenyl-2-cyclohexen-1-one lost hydrogen bromide spontaneously. Recrystallization of the product gave 8 5 9 0 % yields of a compound (11),m.p. 123-121'. The infrared spectrum indicated bonded hydroxyl (3300 cm.-I) and conjugated carbonyl (1645 cm.-I). The compound gave analysis corresponding to C36H3002. Compound I1 proved to be an equimolar complex of 3,5-diphenylphenol (m.p. 9403) and 3,5diphenyl-2-cyclohexen-1-one (m.p. 82,' 8906), and mas also prepared by recrystallizing a mixture of I and I11 from hexane or ethanol. Compound formation was demonstrated by the method of Kofler6 using a hot stage microscope. By heating a slide covered half by the phenol and half by the ketone, melting was observed a t 85" and 92" corresponding to the two eutectics, at 89" and 94" for the two pure components, and a t 124" for the compound, 11. The solution characteristics of I1 indicate essentially complete dissociation in dilute solution. The molecular weight, by cryoscopic or ebullioscopic methods, is 246 (theor. 246). The ultraviolet spectrum of 11, in ethanol, is equal to the sum of the spectra of its two components. The strongly bonded hydroxyl frequency shifts to shorter wave lengths on dilution in chloroform as would be expected if dissociation occurred. Compound I1 may be separated into its components by extraction of the phenol from a solution of I1 in benzene-petroleum ether with Claisen's alkali or by chromatography on Woelm acid alumina grade one. The components may also be separated by the preparation of ketone (2,4-dinitrophenylhydrazone) or hydroxyl (methyl ether) derivatives. The overall yield of the phenol, using the alkali separation, based on I is 75-807,, allowing (4) E. Knoevenagel, Ann., 281, 59 (1894). (5) IT. Dieckniann, and K. von Fischer, Ber., 44, 971 (1911). (G) A. Icofler, 2. physik. Chem., A. I
