1682
RAMSDEN, LEEBRICK, ROSENBERG, MILLER, WALB URN, BALIKT, AND CSERR
dic:*clohexylmethyltin iodide, b.p. 136-140" a t 0.65 mm., 20.8 g. In the cleavage of dicyclopentyldimethyltin the cyclopentyl iodide isolated was characterized: b.p. 41-43' at 6.8 mm., ny 1.5465 (lit.13n y 1.5457). Dicyclopentyldiphenyltin was treated with two eauivdents- of' iodine .and- dicyciohexyldiphenyltin with * one ecluivalent. The iodobenxene resulting from the cleavage LVUS recovered by distillation, The organotin cleavage prodiict,s were not isolated. (13) M. T. Rogers and J. D. Roberts, 6 8 , 8.43 (1946).
[CONTRIBUTION FROM
THE
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22
Acknowledgments. The author wishes to express his appreciation 'to the United States Office of Naval Research for support of this work, which may be reproduced in whole or in part for any purDose of the United States Government. Grateful acknowledgment is made of advice and encouragement freely given by ProfessorE~~~~~G. ~~~h~~ throughout the course of this work.
J. Am. Chem. Soc., CAMBRIDGE 38, MASS.
RAHWAY RESEARCH LABORATORY O F THE METALAND THERMIT CORP.]
Preparation of Vinylmagnesium Chloride and Some Homologs' HUGH E. RAMSDEN, JACK R. LEEBRICK, SANDERS D. ROSENBERG, EDITH H. MILLER, JOHX J. WALBURN, ALLEN E. BALINT, AND ROBERT CSERR Received M a y 23, 1967 Vinylmagnesium chloride and several of its homologs were prepared. Among the homologs were 1-propenyl, 2-propenyl, l-but-l-enyl, 2-but-2-enyl, 4-methyl-2-pent-l-eny1, and l-cyclohexenyl magnesium chlorides. Several characterizing reactions of vinylmagnesium chloride were carried out.
Both vinyl chloride and vinyl bromide have long been considered to be unreactive toward magnesium to form vinylmagnesium halides. Krestinsky2 reported a lack of success in preparing vinylmagnesiuni bromide in ether. A u s t e r ~ e i l ,however, ~ reported a successful Wurtz reaction of vinyl bromide with 2-chloropropene to form isoprene. A patent4 issued to the General Electric Co. showed a more recent use of vinylmagnesium bromide in ether to form vinylsilanes. Quite recently, Normants has shown in excellent researches the attaining of g o d results using tetrahydrofuran as solvent for he preparation of vinylic magnesium bromides in high yield. Pn many subsequent papers Normant and co-workers hare shown the use of several vinylic magnesium bromides to prepare olefinic derivatives However, Braude in attempts to repeat (1) Parts of this paper were presented a t the 130th National Meeting of the AMERICAN CHEMICAL SOCIETY, Atlantic City, September, 1956. ( 2 ) W. Krestinsky, Ber., 55B,2770-2774 (1922). (.3j G. Austerweil. German Patent 245.180 (1912): [Chem. . . Adslr. 6, 2334 (1912)l. (4) J. Pyle, U. S. Patent 2,448,391 (1948); [43, 1223 rlo4o)l. ( 5 ) H. Normant, Compt. rend., 239, 1510 (1954). (6) H. Kormant, Compt. rend., 239, 1811 (1954). (7) H. Normant, Compt. rend. 240, 314 (1955). (8) H. Sormant, Compt. rend., 240, 440 (1955). (9) H. hormant, Compt. rend., 240, 631 (1955). (10) I%, rormant, Compt. rend., 240,1111 (1955). (11) H. hormant, Compt. rend., 240, 1435 (1955).
(12) J. Ficini, Bull. SOC. chim. France, 119 (1956). (13) M. Xormant and C. Crisan, Compt. rend. 240, 1946 (1955). (14) N.Norrnont and P. Maitte, Bull. aoc. chim. France, 351,1439 (1956),
Normant's preparation of l-isobutenylmagnesium bromide reported complete lack of success.17 This article is in part confirmation of Normant's preparation of vinylic magnesium bromides. Since Normant has not shown the generality of this preparation by extending it to vinylic chlorides,'* we would like to do so here in reporting work done independently. l 9 o 2 O Vinylmagnesium chloride was prepared by passing vinyl chloride into tetrahydrofuran and active magnesium. The Gilman titrationz1showed a 98.5% yield of Grignard reagent and recovery of magnesium showed a 94.5% consumption. Carbonation yielded acrylic acid. These results appear to be the first preparation of vinylmagnesium chloride. Vinyl chloride is remarkably soluble in tetrahydrofuran and this property may be used to advantage in preparing vinylmagnesium chloride in techniques similar to those used for arylmagnesium
(15) H. Normant and J. Ficini, Bull. SOC. chim. France, 1441 (1956). (16) a. V. Levy and H. Normant, Compt. rend., 242, 202 (1957): b. H. Normant and G. Martin, Bull. SOC. chim. France, 429,728 (1957). (17) E. A. Braude, J . Chem. SOC.,3324 (1955). (18) Chem. Abstr., 50, 228 (1956) the abstract of ref. 5 states vinylmagnesium chlorides can be made, which is true, although Normant did not so state in ref. 5. (19) I n extensive private communications with Normant during 1955 it was determined that his work and ours were initiated at about the same time, very much prior to 1954. (20) a. This work is covered by patent applications. b. H. E. Ramsden and A. E. Balint, Brit. Pat. 777,158 (June 19,1957). (21) H. Gilman, H. A. Zoellner, and J. B. Dickey, J,A m . Chem. SOC.51, 1576 (1929).
DECEMBER
1957
chlorides.zz Addition of the vinyl chloride-tetrahydrofuran solution to magnesium, activated by ethyl bromide in the presence of a few milliliters of the solution, leads to a rapid initiation and reaction to give high yields (above 90% consistently) of vinylmagnesium chloride, in a few hours time. However, purity of the vinyl chloride is essential and particularly important is very low contamination by the phenolz3usually used to stabilize the vinyl chloride. Vinylmagnesium chloride in tetrahydrofuran is relatively stable. It has been stored for as much as a month with no loss of activity. No polymerization occurs during either preparation or storage. However, if the tetrahydrofuran is removed by vacuum distillation without a concomitant replacement by another solvent, a violet decomposition reaction sets in when the solution becomes quite concentrated. I n one such reaction, a serious fire resulted when the rapidly rising internal pressure blew out the thermometer well. Use of a displacing solvent such as toluene or cumene avoids this decomposition. In its reactions, vinylmagnesium chloride appears to be a t least as reactive as ethylmagnesium chloride. Reactions with carbonyl functions, as in aldehydes, ketones, and esters, with metal salts such as tin, lead, silicon,z4antimony, aluminum, and other metal and metalloid halides, with olefin oxides, alkyl halides, and with other reactive molecules have been carried out. With paraformaldehyde and with ethylene oxide, vinylmagnesium chloride yields the expected allyl alcohol and 3-buten-1-01. It gives a strong positive reaction in the well known Gilman Color Test I.26 Several compounds prepared using vinylmagnesium chloride are identical to compounds prepared by Normant with vinylmagnesium bromide. A comparison of yields obtained with vinylmagneTABLE I
Compound Prepared Phenyivin ylcarbinoi Propylvin ylcarbinol Dimethylvinylcarbinol Divinylcarbinol Linalool
1603
VINYLMAGNESIUM CHLORIDE
Yieldfi. % VinylVinylmagnesium magnesium chloride bromide 54 (85)' 75 79.50 68.5 (90)' 80.5
677 E57 947
60'0 839
' The yields in parentheses have been obtainrd in more recent work. The dimethylvinylcarbinol easily dehydrated t o form isoprene. (22) H. E. Ramsden, A. E. Balint, W R. Whitford, J. J. Wa;burn, and R. Cserr, J.Grg. Chem 1 2 , 1202 (1957). (23) Private romniunication from the Matheson Co.
.
(1954).
(24) S. D. Rosenberg, J. J. Walburn, T. D. Stankovich, A. E. Balint, and H. E. Ramsden, 6.Grg. Chem.. 22, 1200 (1957). (25) H. Gilman and F. Schuitz, 9.Am. Chcna. SJC.,47, 2002 (1925).
sium chloride and vinylmagnesium bromide is shown in Table I. They illustrate that the two reagents give about the same yields of products. I n agreement with Normant,s we have found that 2-methyltetrahydrofuran and tetrahydropyran are suitable solvents for this preparation. Dihydropyran and ethyl tetrahydrofurfuryl efher also function as effective solvents, although tke dihydropyran is too unstable to be useful in further reactions. In addition to vinyl chloride several other hornologs were tried to test the generality of the preparation. These compounds and the yields of Grignard reagents prepared from them are summarized in Table 11. TABLE I1 Reactant
Grignard Yield,'
1-Chloropropene-1 2-Chloropropene 1-Chlorobutene-1 2-Chlorobutene-2 1,l-Dichloropropene-1 2 Chloro-4-methylpentene-1 1Chlorocyclohexene-1
10 24 15 50 27' 88 19
yg
____
' Determined by Gilman titration.21 " Accompanictl by a? evolution of gas.
With these compounds it is rather interesting that yields with non-terminal chlorines (Le., those on secondary carbons) are higher than with terminal chlorines. Also, of interest is their apparent lower. reactivity than that of vinyl chloride. This appears somewhat contrary to experience with the bromo compoundsz6where the higher homologs are more amenable to forming Grignard reagents, EXPERIMENTAL
A11 rcactions were carried out in a static atmosphere of dry nitrogen. The vinyl chloride is the commercial grade as supplied by the Matheson Co. The magnesium turnings are those commercially available from the Dow Chemical Co. Tetrahydrofuran was used as supplied by the DuPont Cu. Tetrahydrofuran should be free of peroxides and water. Stabilized material as supplied by DuPont is peroxide-free and functions as well as carefully purified Constant care is necessary to guard against the hrtzard of peroxides with this solvent. Yields of Grignards were determined by a modification of the Gilman titration reported elsewhere.21Melting point? as given were det'ermined on the Fisher Johns appara!up and the point of total melting is given herc. All eompourids wcrc recrystallized several times to give as narroK a rnngc of melting as possible. Boiling points were obtained duriilg distillation through a 16-inch glass-helices-pacltcd co!!imri with a variable take-off head. Vinylmagnesium chloride. Preparation method I . lrito ii lOOO-ml., 3-neck flask, equipped with stainless steei ane1ior stirrer, thermometer, 3-way Y adapter with a gas inkt tube (dipping under the liquid surface), and reflux conclerisei topped by a static nitrogen atmosphere system, xere placed (26) 111. 8. Kharasch and 0. Reinmuth, Grirignard lieuchon of Nonmetallic Substances, Prentlce-Hali, S e w York, ld54. p. 37.
1604
RAMSDEN, LEEBRICK, ROBENBERG, MILLER, WALBURN, BALINT, AND CSERR
magnesium turnings (1 g.-atom) and 300 ml. of tetrahydrofuran. After the system had been flushed out with nitrogen, an iodine crystal and 2 ml. of ethyl bromide were added to activate the magnesium, and vinyl chloride was passed in through the gas inlet tube. Intermittent heat from an infrared lamp was applied. After 35 min. the temperature was 35" and a light green color appeared, deepening to a deep green, gradually changing to blue, and h a l l y to murky white. The temperature, meanwhile, increased to 42". After 51 min. the temperature had reached 52" (without any external heating after the temperature had reached 35"). Heat was applied to bring the mixture to reflux. A deep brown color began developing and the heating was continued for 2.5 hr., after which the reaction was stopped overnight. In the morning the reaction mixture was rapidly heated to 50" and heating removed. Reaction of vinyl chloride with the magnesium maintained the temperature between 50 and 52" until completion of reaction 3.75 hr. later when the temperature fell sharply. The reaction mixture was diluted with tetrahydrofuran to 1000 ml. in a volumetric flask and 20-ml. aliquots titrated by a modification of the Gilman titration2* (addition to 50 ml. portions of 0.5N HZSO4 and the excess HzSO~ back titrated using 0.2N NaOH and bromo-cresol purple indicator) to obtain a yield of 98.5'%',. Magnesium (1.38 9.) was recovered, indicating use of 94.5% of the magnesium. Vinylmagnesium chloride. Preparation method II ( p r e ferred technique). A. Preparation of solution. Vinyl chloride gas was passed into tetrahydrofuran (984.0 g.; 13.67 moles) in a weighed 2-neck flask, equipped with a Scott condenser (coolcd by Dry Ice-acetone mixture) and a gas inlet tube, until about 3.5 moles were absorbed (actually 239.4 g. were absorbed). B. Preparation of Grignard. Ethyl bromide (4 ml.) was added to a mixture of 3.0 g.-atoms (72.9 g.) of magnesium turnings and 15 ml. of the vinyl chloride-tetrahydrofuran solution in a 3000-ml. 3-neck flask equipped with a stainless steel anchor stirrer, thermometer, Scott condenser (cooled with Dry Ice-acetone), and a large capacity dropping funnel. Initiation was immediate; the vinyl chloride solution was then added as rapidly as possible, controlling the temperature of reaction at about 50" by the rate of addition. Aft,er completion of addition, the mixture was heated for 0.75 hr. at 50" and then cooled. This was used as a stock solution. Titration of a 10 ml. sample showed it to contain 22.6 mil. equiv. of vinylmagnesium chloride. The yield in this procedure varies from 90-98% depending on the technique. A411yZ alcohol. Trioxymethylene (90.1 g.; 1 mole) was slurried in 150 ml. of tetrahydrofuran in a cooled stirred flask. To this slurry was added 442 ml. (equivalent to 1 mole) of the stock solution of vinylmagnesium chloride. Stirring was continued for 2.0 hr. a t which time a negative Color Test I was obtained. Sulfuric acid (28 ml. concd. H2SOr and 100 ml. HzO) was then added and the mixture filtered. The precipitate was slurried in 250 ml. tetrahydrofuran and filtered. The filtrates were combined and distilled. After removal of solvent, a large (60 ml.) fore-cut boiling 66-86' was obtained and a 10 ml. fraction boiling a t 97-99' (ng 1.4125) was obtained. Allyl alcohol has ny 1.4134.!'.7 A repetition of this procedure gave 30.3% yield, a-naphthvlurethane. m.13. 107' (Lit. 109"a): .. uhenvlurethane., m.13.7d" (Lit. 7Oo*a). Carbonation. A solution of vinvlmaenesium chloride in tetrahydrofuran (from 1.0 g.-atom of Gagnesium and prepared by gaseous method) was added to a large excess of powdered Dry Ice. After evaporation of the Dry Ice, 1.1
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22
moles of hydrochloric acid (37% solution), 500 ml. water, and 500 ml. of ethyl ether were added and the two layers separated. The aqueous layer was extracted three times with 100-ml. portions of ether, the extracts combined with the organic layer, and the whole distilled. Twenty milliliters of acrylic acid (with n y 1.4223)" was obtained, boiling at about 140". Repetition of this procedure using vacuum distillation yielded 37.0 g. (52.6%) of acrylic acid; b.p. 81" (88 mm.). 3-Butenol-I. To vinylmagnesium chloride (1 g. atom magnesium and 1 mole vinyl chloride in 3.0 moles tetrahydrofuran) was added 1mole (44 g.) of ethylene oxide in 150 ml. of tetrahydrofuran at 20". After 1 hr. further stirring, the solvent was evaporated under an aspirator vacuum, the paste treated with 550 ml. of water and 100 ml. of 37% HCl. The organic layer was separated and combined with two 100-ml. ethyl ether extracts of aqueous layer. This solution was neutralized by saturated NaHCOs solution, and dried over K2COs. Solvents were removed under vacuum (0.2 g. hydroquinone added) and the residue fractionated through a Todd column. The product fraction which came over at 50' (40 mm.) weighed 48.3 g. (67.1%); ny 1.4221; phenylurethan, m.p. 21". The literature gives ny 1.422;29 phenylurethane, m.p. 23.5-24.5. Phenylvinylcarbinol. To a stirred solution of 1 mole of vinylmagnesium chloride in tetrahydrofuran was added, dropwise, 104.5 g. (0.9 mole) of freshly distilled benzaldehyde (Matheson). Stirring was continued for 1 hr., the mass was cooled and hydrolyzed by addition of saturated ammonium chloride solution. The layers were separated, the organic layer treated with dilute sodium bicarbonate solution and distilled at atmospheric pressure until the tetrahydrofuran was removed, The residue was distilled under reduced pressure to yield 73.5 g. (60%) of phenylvinyl carbinol; b.p. 76-77' (3 rnm.);'6ny 1.5417 (lit.31ny.' 1.5464); p-nitrobenzoate, m.p. 47' (lit.sz d. 48"). Propylvinylcarbinol. To eight-tenths mole vinylmagnesium chloride was added, dropwise, 58 g. (0.8 mole) of nbutyraldehyde a t 0-10". Stirring was continued for 1 hr. After hydrolysis with 200 ml. of saturated ammonium chloride solution, the organic layer (and two 100-ml. portions of tetrahydrofuran used to extract the aqueous phase) was distilled to remove tetrahydrofuran and then distilled a t about 100 mm. The fraction boiling a t 77-79" (96 mm.) weighed 60.3 g. (75%); Iodine no. 246 (calcd. 254); ny 1.4272. (Lit.? nl,B 1.4297); p-Nitrobenzoate, m.p. 59" (lit.33 60-62 " ). Dimethylvinylcarbinol and isoprene. To vinylmagnesium chloride (prepared from 2 moles vinyl chloride, 2.0 g. atoms of magnesium, and 6.0 moles of tetrahydrofuran) was added 116.0 g. (2.0 moles) of acetone and the mixture was stirred for 1 hr. After hydrolysis with 166 ml. of 12N hydrochloric acid in 500 ml. of water, the organic layer (and two 100-ml. portions of xylene used to extract the aqueous phase) was fractionated in a Todd column. A fraction distilling a t 9596" was obtained. weighing 135.7 g. (79.5%); ny 1.4189 (Lit.84 ny 1.4125); d:' 0.8270, (lit.$6 0.8255). This fraction waa distilled from 12 g. aniline hydrobromide
(29) H. Waldman and R. Petri, Chem. Re?., 83, 287 (1950). (30) I. Heilbron, Dictionary of Organic Compounds, Yol. I, Oxford University Press, New York, 1953, p. 55. (31) E. A. Braude, E. R. H. Jones, and E. S. Stern,'J. Chem. Soc., 401 (1946). (32) I. Heilbron, Dictionary of Organic Compounds, Vol. rv,p. 98-99. (33) I. Heilbron, Dictionary of Organic Compounds, Vol. 11,p. 678. (34) I. N. Nazarov, V. N. Rakcheeva, and L. I. Shmonina, (27) Handbook of Chemistry and Physics, 31st ed., ChemZhur. ObsheW. K h i m . 22,442 (1952 [Chem. Abstr., 47,5370a ical Rubber Publishing Co., Cleveland, Ohio. (28) It. L. Shriner and R. C. Fuson, Identification of Or- (1953)l. (35) F. J. Soday, U. S. Patent 2,382,031; [Chem. Abstr., ganic Compoimds, 3rd ed., John Wiley and Sons, Inc., New 40,3469 (1946)j. yolk, 1948, p. 226.
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I
DECEMBER
1957
1605
VINYLMAQNESIUM CHLORIDE TABLE I11
Reactant, Wt., Moles
Magnesium, G.-Atoms
Reaction Time, Hr. After Addition addition
Yield, % (by Titration)
Remarks
2-Chloropropene 76.5 g. (1.0)
24.3 g. (1.0)
1.0
25.5
24
Heated throughout. Mg used, 8.3 g. (34.3%)
1-Chlorobutene-1" 40.6g. (0.45)
11.6g.(0.45)
7.0
16.3
14.8
Heated throughout. used, 25.8%
Mg
2-Chlorobutene-2' 45.3g. (0.5)
12.2g.(0.5)
3.0
5.3
49.7
Heated throughout. used, 56. 5y0
Mg
2-Chloro-4-methylpentene-1' 59.3 g. (0.5)
12.2g.(0.5)
1.25
2.25
87.8
Heated throughout. used, 93.3%
Mg
1-Chlorocyclohexene 58.3g.(0.5)
12.2 g. (0.5)
1.66
13.2
19.2
Heated throughout. used, 28.7%
Mg
1,l-Dichloropropene (1.0) 111.og.
24.3 g. (1 .O)
1.66
1.25
26. 7d
a Prepared by KOH/ethylene glycol dehydrochlorination of 1,l dichloropropane.40 Prepared from methyl ethyl ketone and Pc15.40Prepared from methyl isobutyl ketone and Pc15;40b.p. 37-39.5 (65 mm). Kegative color test. hllene or methylacetylene was given off copiously; this material formed a bromide of 87% Br content; ny 1.5121.
under a 4-inch packed column. Material boiling at 33-36' was removed to yield 64.7 g. (47.5% based on magnesium, 58.5% based on dimethylvinylcarbinol) of isoprene; ny 1.4211 (lit.36 1.4216); tetrabromide, b.p. 157" (lit.*' 155160). Divinylcarbinol. To 1.0 mole of vinylmagnesium chloride in tetrahydrofuran was added 27.0 g. (0.45 mole) of methyl formate at 0-5". After 1.0 hr. further stirring, 250 ml. of saturated ammonium chloride solution was added. The organic layer (and three 75-ml. portions of tetrahydrofuran used to extract the aqueous layer) was distilled (0.1 g. hydroquinone added) at 100 mm. to remove tetrahydrofuran. The fraction boiling a t 56' (80 mm.) weighed 20.9 g. (55%). Five more grams were obtained on refractionating the forerun to bring the total yield to 25.9 g. (68.5%); ny 1.4474 (Lit.38 ~ L D1.4400); a-naphthylurethane; m.p. 100' (lit.37 100-101'). Repetitions of this procedure have given yields of 90%. Linalool. Two moles (252.0 g.) of methyl heptenone (2methylhept-2-en-6-one from Trubek Laboratories) were added to vinylmagnesium chloride (prepared from 53.5 g., 2.2 g.-atoms, of magnesium, 137.5 g., 2.2 moles, of vinyl chloride, and 475 g., 6.6 moles, of tetrahydrofuran), which had Seen freed of magnesium particlea by filtration, over a (36) I. Heilbron, Vol. 111, p. 106, (37) Reilstein, VoI. I, p. 138. ( 3 8 ) 1. Heilbron, Vol. IV, p. 61.
period of 1.5 hr. a t a temperature of 30-35". After 1 hr. of further stirring, the mixture wa8 cooled and hydrolyzed with 172 ml. of 37y0 hydrochloric acid and 522 ml. of water. The organic layer was washed with 200 ml. of saturated sodium bicarbonate solution and with water, dried over anhydrous sodium sulfate, filtered, and vacuum-distilled. A fraction was obtained (b.p. 65-68" a t 6 mm.) which weighed 246.7 g. (80.5%); n",", 1.4609 (lit.39 ng 1.462). A further 29.5 g. (9.6%) was recovered from forerun and holdUP. I-Propenylmagnesium chloride. A solution of l-chloropropene (76.5 g., 1 mole) in 3.0 moles of tetrahydrofuran was added dropwise to 24.3 g. (1 g.-atom) of magnesium turnings (activated by 2 ml. of ethyl bromide and 15 mi. of the solution). Heating a t reflux was necessary for the 5.5 hr, required for addition and for 17.5 hr. afterwards. A yield oi 9.3% (titration) was obtained. Homologs preparations. Preparations of the homologs are summarized in Table I11 because of their similarity t o the preparation of 1-propenylmagnwiiim chloride. The tetrahydrofuran was always used in the ratio of 3 moles to one of chloride.
RAHWAY, N. J. (39) P. Z. Bedoukian, Perfumery Synthetics and Isolates, D. Van Nostrand Co., Inc., New Hork, 195!., p. 292. (40) T . L. Jacobs, Org. lleactions, V, 20 (1949).
