Org. Synth. 1979, 59, 176
DOI: 10.15227/orgsyn.059.0176
TERTIARY ALCOHOLS FROM HYDROCARBONS BY OZONATION ON SILICA GEL: 1-ADAMANTANOL
[Tricyclo[3.3.1.13,7]decan-1-ol]
Submitted by Zvi Cohen, Haim Varkony, Ehud Keinan, and Yehuda Mazur
1.
Checked by Frank E. Blaney and Robert M. Coates.
1. Procedure
Caution! Ozone is extremely toxic and can react explosively with certain oxidizable substances. Ozone also reacts with some compounds to form explosive and shock-sensitive products. Ozone should only be handled by individuals trained in its proper and safe use and all operations should be carried out in a well-ventilated fume hood behind a protective safety shield.
Caution! Ozone is toxic and potentially explosive. This procedure should be carried out in an efficient hood and behind a suitable protective shield.
A solution of 6 g. (0.044 mole) of adamantane (Note 1) in 100 ml. of pentane and 500 g. of silica gel (Note 2) are placed in a 2-l., round-bottomed flask (Note 3). The pentane is removed by rotary evaporation at room temperature under reduced pressure (20 mm.), and the resulting dry silica gel is allowed to rotate for an additional 2 hours (Note 4). The adamantane–silica gel dispersion is poured through a powder funnel into the ozonation vessel (Note 5), which is then immersed in a 2-propanol–dry ice bath at −78°. A flow of oxygen is passed through the vessel at a rate of 1 l. per minute for 2 hours, after which the internal temperature reaches −60 to −65° (Note 6). The ozone generator (Note 7) is turned on, and the ozone–oxygen mixture is passed through the vessel for ca. 2 hours, causing the silica gel to become dark blue (Note 8) and (Note 9). The cooling bath is removed, and the vessel is allowed to warm to room temperature in the hood over a 3-hour period. The silica gel is transferred to a chromatography column, and the organic material is eluted with 3 l. of ethyl acetate. Evaporation of the solvent affords 6.1–6.4 g. of crude adamantanol (Note 10), which is dissolved in 200 ml. of 1:1 (v/v) dichloromethane–hexane by heating on a steam bath. The solution is filtered, concentrated to incipient crystallization and placed in a freezer at −20°. After a crop of fine, white needles (3.0–3.2 g.), m.p. 280–282° (sealed capillary), is collected, the mother liquor is concentrated and cooled to separate two additional crops, which give 2.2–2.6 g. and have melting point ranges of 270–274° to 275–280° (sealed capillary) (Note 11). The total yield of 1-adamantanol is 5.4–5.6 g. (81–84%) (Note 12).
2. Notes
1.
Adamantane is available from Aldrich Chemical Company, Inc., and Fluka AG, Buchs, Switzerland.
2.
Silica gel 60, with particle sizes ranging from 0.063 to 0.200 mm. (70–230 mesh), is suitable and may be purchased from Brinkmann Instruments, Inc., or E. Merck, Darmstadt, Germany. The submitters report that silica gel of this type normally contains
ca. 5% water, which may be removed by drying at 300° for several hours, and that somewhat better yields are obtained when the silica gel is dried in this manner before use.
3.
The submitters have found that the absorption of
adamantane on
silica gel may also be accomplished by mixing the dry solids in a closed flask for a few hours.
4.
Heating should be avoided to prevent loss of some of the
adamantane through sublimation.
5.
The submitters have used both a
tightly closed, 1-l. gas-washing bottle and the apparatus shown in
Figure 1 for ozonation vessels. They recommend that the glass joints not be greased. The apparatus used by the checkers consisted of a
cylindrical, two-necked vessel having dimensions given in
Figure 1. One neck of the vessel was fitted with a
Claisen distillation head and the other with a
thermometer with its bulb positioned in the middle of the vessel. A
bent gas-dispersion tube with an extra-coarse sintered-glass frit extending through the vertical branch of the Claisen head to within 2–3 mm. of the center of the bottom of the flask served as the gas inlet. The curved branch of the Claisen head was fitted with a drying tube and this functioned as the gas exit.
Figure 1.
6.
The checkers found that the maintenance of a flow of
oxygen during the cooling period prevented clogging of the glass frit and a building up of pressure in the gas-inlet tube in their apparatus.
7.
A
Welsbach T-816 Ozonator purchased from the Welsbach Corporation, Philadelphia, Pennsylvania, was used. The
oxygen stream was dried by passage through dry silica gel and molecular sieves and introduced into the ozonator with the operating voltage set at 115 V., the gas pressure at 8 p.s.i.g., and the gas flow rate at 1 l. per minute. The resulting
ozone flow rate was 0.00245 mole per minute, as determined by titration of a
potassium iodide trap.
Org. Synth., Coll. Vol. 5, 489 (1973)]
2.
8.
In the apparatus used by the checkers, the internal temperature was between −45° and −65° while
ozone was being passed through the
silica gel. The use of lower bath temperatures results in the adsorption of a greater quantity of
ozone on the silica gel; consequently, shorter reaction times and higher conversions were realized.
However, since ozone liquifies at −112°,
there is a serious danger of explosion.9.
The
ozone flow is stopped when the silica gel reaches a constant, dark blue color. The time required for saturating the silica gel with
ozone depends on the type of silica gel used and on whether it has been dried
(Note 2).
10.
A GC analysis on the crude
adamantanol was carried out by the checkers using a
1.8 m. × 3 mm. column packed with 5% silicone oil (SE-30) supported on Chromosorb W and the following column temperature program: hold at 120° for 6 minutes and then increase at
ca. 8° per minute. The chromatogram of the product from one run showed a major peak at retention time of 10 minutes and three minor peaks with retention times of 11.2, 12, and 13.7 minutes and relative areas amounting to 1.5, 1.6, and 4% of the major peak, respectively. A GC analysis by the submitters with
5% diethylene glycol succinate supported on Chromosorb W as a stationary phase at 110–160° showed peaks for
adamantan-1,3-diol and
adamantanone, as by-products totaling 7%, in addition to the peak for
1-adamantanol.
11.
A GC analysis by the checkers (see
(Note 10)) on the material in the third crop from one run showed a major peak for
1-adamantanol and a second minor peak having an area
ca. 12% of that of the major peak. In another run the area of the peak from this by-product in the third crop was less than 2% relative to that of
1-adamantanol.
12.
A yield of
5.8 g. (
87%), m.p.
280–282°, was obtained by the submitters. The IR,
1H NMR,
13C NMR, and mass spectra of the product were identical to those of an authentic sample of
1-adamantanol. A mixed melting point with an authentic sample of
1-adamantanol showed no depression.
The spectral characteristics of the product are as follows: IR (KBr) cm.−1 3350(OH), 1455, 1352, 1302, 1118, 1088; 1H NMR (CDCl3), δ (multiplicity, number of protons, assignment): 1.53 (s, 1H, OH), 1.55–1.80 (m, 12H, 6 CH2), 2.17 (broad s, 3H, 3CH); 13C NMR (CDCl3), δ (assignment): 30.7 (3CH), 36.1 (3CH), 36.1 (3CH2), 45.4 (3CH2), 68.2 (COH).
3. Discussion
This "dry ozonation" procedure is a general method for hydroxylation of tertiary carbon atoms in saturated compounds (Table I).
3,4,5,6 The substitution reaction occurs predominantly with retention of configuration. Thus,
cis-decalin gives
cis-1-decalol, whereas
cis- and trans-1,4-dimethylcyclohexane afford
cis- and trans-1,4-dimethylcyclohexanol, respectively. The amount of epimeric alcohol formed in these ozonation reactions is usually less than 1%. The tertiary alcohols may be further oxidized to diols by repeating the ozonation; however, the yields in these reactions are poorer. For instance,
1-adamantanol is oxidized to
1,3-adamantanediol in
43% yield. Secondary alcohols are converted to the corresponding ketone. This method has been employed for the hydroxylation of tertiary positions in saturated acetates and bromides.
TABLE I
PREPARATION OF TERTIARY ALCOHOLS FROM HYDROCARBONS WITH OZONE ON SILICA GEL
|
|
Hydrocarbon
|
Tertiary Alcohol
|
Conversion (%)
|
Yield (%)a
|
|
|
|
>99.5
|
65b
|
|
|
72
|
79c
|
|
|
92
|
76d
|
|
|
>99.5
|
99
|
|
|
88
|
72e
|
|
|
>99.5
|
90
|
|
a Based on the amount of hydrocarbon consumed, as determined by GC.
|
b A mixture of the three methyl cyclohexanones was also formed to the extent of 34%.
|
c The epimeric alcohol was also present to the extent of 0.6%.
|
d The epimeric alcohol was also present to the extent of 3.5%.
|
e trans-1-Decalone (10%) and trans-2-decalone (16%) were also formed.
|
Dry ozonation may be carried out according to the following alternative procedure: The ozone–oxygen mixture is passed through the silica gel at −45°C followed by removal of the excess ozone at the same temperature (−45°C) by passing an inert gas (nitrogen or argon) through the sample.
1-Adamantanol has been prepared by oxidation of
adamantane with peroxyacetic acetic
7 and by hydrolysis of
1-bromoadamantane with
silver nitrate8 or
hydrochloric acid.
9
Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)
silica gel
hydrochloric acid (7647-01-0)
ethyl acetate (141-78-6)
silver nitrate (7761-88-8)
oxygen (7782-44-7)
nitrogen (7727-37-9)
methyl (2229-07-4)
Pentane (109-66-0)
dichloromethane (75-09-2)
ozone (10028-15-6)
hexane (110-54-3)
argon (7440-37-1)
Adamantane (281-23-2)
1-Adamantanol,
adamantanol,
Tricyclo[3.3.1.13,7]decan-1-ol (768-95-6)
1-bromoadamantane (768-90-1)
diethylene glycol succinate
Adamantanone (700-58-3)
adamantan-1,3-diol,
1,3-adamantanediol
cis-decalin
cis-1-decalol
e trans-1-Decalone (21370-71-8)
trans-2-decalone
cis- and trans-1,4-dimethylcyclohexane
cis- and trans-1,4-dimethylcyclohexanol
Copyright © 1921-, Organic Syntheses, Inc. All Rights Reserved