A SIMPLE DURABLE PROTECTOR for CORK STOPPERS* University of Wisconsin, Madison, Wisconsin
C
ORK stoppers can be protected from the solvent action of certain organic substances and also rendered highly impervious to vapors by application of a protective membrane of regenerated cellulose. The cellulose used was the commercial product * Presented before the Division of Chemical Education at the ninety-third meeting of the A. C. S., Chapel Hill, N. C., April 14, 1937.
t Present address:
3105 Cross Street. Madison, Wisconsin.
sold as "transparent clear bottle caps," costing about one cent each in lots of one hundred. The extent to which these caps furnish protection to the stopper is shown in Table 1. Protected stoppers were applied to reflnx condensers and subjected to the boiling vapors for the periods stated in the table, a new protected stopper being used for each solvent. On cork stoppers the protectors failed when exposed
to the following substances a t their boiling temperatures: acetic anhydride, acetyl chloride, benzaldehyde, benzyl alcohol, benzoyl chloride, and furfural. Rubber stoppers were protected against vapors of acetone, methyl, ethyl, isopropyl, normal-, iso-, and tertiarybutyl, and amyl (B.P. 127.6°C.) alcohols, but swelled on exposure to vapors of benzene, carbon tetrachloride, npropyl alcohol, diethyl ether, ethyl acetate, and pyridine. This swelling frequently caused the protector to crack and expose the stopper.
forty-eight hours of continuous boiling in a room with a minimum temperature of 31°C. Each protector was used for only a single solvent. All solvents were purified and immediately before use were distilled from an
Tirns, susstnnrc
hour5
Acid, acetic, glacial
3
Acid, n-butyrie, 81 per cent.
3
Acid, propionie, 84 per cent.
3
Prvlrrlor Intact, but soft, stick, very thin, brittle Thin, but in
Slomn Shrunk
Shrunk
tact
Alcohol, methyl Alcohol, ethyl Alcohol, n-propyi
42
Satisfactory
170 42
Satisfactory Satirfaetory
Alcohol, isapropy1
42
Satisfactory
Aleohol, n-butyi
42
Satklactory
Alcohol, isobutyl
42
Satisfactory
Alcohol, tertiary butyl
42
Sztisfactory
Alcohol, amyl, a.~.1278'C.
87
satisfactory
89 45 67 42 89 42
Satisfactory satisfactory satirlactory Satisfactory Satisfactory Satisfactory Satisfactory
3 48
Satisfactory Satisfactory
P,."dine
160
water
52
Satisfactory. stained Satirfactory. stained
Carbon dis"l6de Chloroform Dietby1 ether Ethyl acetate Nitrobenzene. M.P. 5.4-C. Phenol
168
stained Shrunk Satisfactory, but stained Satiefacforv, but stained Satisfactory, but stained Satisfactory, but stained Satidactory, but stained Satisfactory, but stained Satisfactory Satisfactory Satisfactory Satisfactmyf Satidmetory Satisfactory Satisfactory, but stained Satiefactory Satisfactory, but stained Satinfactory, but stained Satisfactory, swelled
I STOPPER PROTECTOR READYFOR USE all-glass still directly into the boil in^ flask of the extraction apparatus. For each solvent the wei~htof extract given in Table 2 i s the average of two determina-
*See Table 2 for additional data. f R e ~ i oextracted from cork was deposited between cork and protector.
Since a protector must serve a twofold purpose, first. prevent leaching of the stopper, thereby con
