I N D U S T R I A L A N D ENGINEERIXG CHEMISTRY
January, 1923
61
Permanence of the Grignard Reagent' By Henry Gilman and Charles H. Meyers DEPARTMENT OF CHEMISTRY, I O W A STATF COLLEGE, AYES, IOWA
T
HE GRIGNARD REAGENT is extensively used in organic chemistry, particularly for the preparation 2-28-22 4-2 -22 5-24-22 6-26-22
of the so-called fine or research chemicals. Its
industrial applications are now largely in the fields of drug and perfume synthesis. The reagent is generally prepared by adding a solution of the appropriate R X compound in absolute ether to magnesium turnings. The RMgX compound so formed is conveniently used directly after preparation. In connection with a series of investigations which, it is hoped, will extend the general usefulness of the reagent, more especially where reasonably large quantities are used, a study has been made of its permanence. In a preliminary note2 mention was made of the permanence of ethereal solutions of ethylmagnesium iodide and phenylmagnesium bromide, both when exposed to daylight and when kept in the dark. It has since been found that this applies to a rather complete series of representative RMgX compounds, some in highly concentrated solutions. All the solutions investigated were protected from the atmosphere, because water, carbon dioxide, and oxygen react with RMgX compounds.
EXPERIMENTAL The Grignard reagent was prepared in the customary manner--in a ~OO-CC., 3-neck flask provided with a stirrer having a mercury seal, a reflux condenser, and a separatory funnel. Sufficient ether was used to make about 300 cc. of solution. At the end of the reaction the solution was allowed to stand a few hours in order that any sediment in the reaction mixture might settle. About 200 cc. of the ether solution were then drawn up by suction into a gas collector having a volume of 250 cc. The gas collectors used were of standard type-all-glass cylinders provided on each end with a stopcock. After drawing up the sample, the stopcocks were closed and a piece of rubber tubing fitted with a glass plug was placed on the delivery end to prevent clogging in that part below the stopcock. The containers were held upright on a wooden rack. A sample was drawn off for analysis into graduated test tubes niade from burets, the first few cubic centimeters being discarded. The acid-titration method of analysis was selected. This involves essentially the addition of a n excess of standard acid to an aliquot, and then titrating back with standard alkali. The first analysis of each solution wa8 made on the day of preparation. Inasmuch as the analysis extended over several months, it was necessary to determine if an appreciable quantity of ether diffused or leaked through the glass stopcocks. For this purpose two special all-glass collectors were made. These collectors were essentially counterparts of those used, with the exception that an upper portion was constricted to a diameter of 1 cm. This portion was graduated to 0.2 cc. and gave the total volume of the container from 200 cc. to 220 CC. A solution of ethylmagnesium iodide in ether, containing about 10 g. per 100 cc., was drawn into the two containers. The volumes of these solutions were read a t intervals over a 4-mo. period. The following data indicate that the changes in volume, presumably due to a loss of ether, are of no serious moment. Received July 21, 1922. THISJOURNAL, 14 (1922),243.
24 24 23 24
209.3 208.5 207.8 208.0
211.0 209.6 208.0 207.4
DATA T h e following table records the results obtained over a time interval exceeding one-half year. There is no reason for doubting that the permanence extends over a much longer period. RMgX COMPOUND CHaMgI
CzHaMgBrs N-C4HoMgBr
N-CdIsMgBr
iso-CsHnMgBr
cyclo-CeHilMgBr
CsHsMgBr
CeHsMgBr
CeHsCHzMgCl
Date
12-8 -21 2-9 -22 3-31-22 6-19-22 1- 5-22 2- 9-22 3-31-22 12-10-21 2- 9-22 3-31-22 6-19-22 12-11-21 2- 9-22 3-31-22 6-19-22 12-13-21 2- 9-22 3-31-22 6-19-22 1- 4-22 2- 9-22 3-31-22 6-19-22 1-10-22 2- 9-22 3-31-22 6-19-22 1-10-22 2- 9-22 3-31-22 6-19-22 1-11-22 2- 9-22 3-31-22 6-19-22 12-11-21 2- 9-22 3-31-22 6-19-22 12-12-21 2- 9-22 3-31-22
Aliquot of Acid' RMgX Cc.
Base2 Cc.
20.65 21.35 22.93 23.2 21.25 23.4 22.7 22.55 20.2 23.1 21.55 11.95 15.6 19.8 18.13 18.90 20.2 22.5 22.88 22.0 20.3 22.45 22.4 19.8 €7.9 23.3 22.88 13.8 14.7 22.12 18.48 20.45 18.2 23.15 24.17 19.45 20.15 22.7 21.8 19.58 19.5 23.9
17.0 20.0 12.0 10.9 13.0 26.0 23.65 18.0 27.0 15.8 20.4 15.0 25.0 23.8 37.8 34.0 32.0 25.9 25.25 37.0 41.0 35.1 34.8 31.0 35.0 18.7 19.45 31.0 28.0 17.85 38.6 24.0 25.0 19.9 18.85 50.0 35.0 27.55 29.2 34.0 30.0 27.85
100.65 106.2 101.0 100.0 128.45 156.0 150.0 101.4 104.7 100.0 101.0 151.9 204.9 250.0 250.0 100.35 101.9 100.0 101.0 101.7 102.8 100.0 100.0 104.8 104.3 100.0 100.0 151.2 154.0 200.0 200.0 53 4 51.7 50.0 50.0 121.25 102.3 100.0 100.0 59.7 50.65 50.0
AcidBase Cc.
G. RMgX per 1OOcc.
77.97 79.52 84.99 85.46 111.11 121.32 118.45 77.39 68.68 78.92 73.79 131.89 171.55 218.25 199.6 54.99 59.21 65.45 67.32 52.34 48.11 53.18 53.58 63.45 57.6 75.05 74.05 109.85 116.65 176.19 148.5 21.38 18.35 24.65 24.85 54.55 55.61 63.25 61.05 14.34 10.63 12.85
16.2 16.0 15.92 15.83 18.01 17.86 17.97 14.31 14.17 14.24 14.27 46.0 45.84 45.95 45.89 13.18 13.28 13.18 13.33 11.52 11.48 11.47 11.58 15.02 15.07 15.09 15.16 37.29 37.18 37.32 37.65 4.08 3.93 4.15 4.01 14.16 13.93 14.06 14.13 4.38 3.26 3.21
0 2584 N HiSOi determined by precipitating as BaSO4. 1 kc NaOH = 1 .'334cc. HzS04. Coitainer was broken before taking fourth aliquot. 4 Solid cr-GoH?MgBr separated early from solution. This accounts for the first abnormal drop in concentration of solution, and the clogging which prevented the taking of a fourth aliquot. 1 2
8
Fatal Accident at Columbia On November 17, 1922, an accident occurred in the Chemical Engineering Laboratory at Columbia University, killing instantly William E. Spandow and injuring Reginald G. Sloane. Mr. Sloane is apparently now out of danger of any loss of eyesight and probably will have but a slight scar. A number of other students in other parts of the room were uninjured. Mr. Spandow was of the highest type, both personally and as a student. He was in his third year of graduate work in the chemical engineering curriculum. The accident occurred during an experiment where diphenylamine was to be made by heating aniline and aniline hydrochloride in an autoclave. The cover of the autoclave gave way with the disastrous results mentioned above.
