Org. Synth. 1959, 39, 43
DOI: 10.15227/orgsyn.039.0043
9-METHYLFLUORENE
[Fluorene, 9-methyl-]
Submitted by Kurt L. Schoen and E. I. Becker
1.
Checked by William S. Johnson and V. B. Haarstad.
1. Procedure
An 850-ml. steel bomb is charged with a solution of 23 g. (1.0 g. atom) of sodium in 450 ml. of absolute methanol and 113 g. (0.68 mole) of fluorene (Note 1). The vessel is then closed, heated to 220° (Note 2), and rocked for 16 hours (Note 3). The reaction vessel is allowed to cool, and the contents are transferred to a 2-l. beaker with the aid of small volumes of benzene and then water to complete the transfer. The reaction mixture is diluted with an equal volume of water, neutralized with concentrated hydrochloric acid, and extracted with three 150-ml. portions of benzene. The combined benzene extracts are washed with three 200-ml. portions of water, and the solvent is removed by distillation at atmospheric pressure. The residue is recrystallized from methanol (1 l. per 100 g. of solute) to give 96–106 g. (78–86% yield) (Note 4) of colorless 9-methylfluorene, m.p. 44–45° (Note 5).
2. Notes
1.
A
commercial grade of fluorene was purified by crystallization from
methanol until the m.p. was
113–114°.2.
In the checkers' experience the temperature must not be below 220° or a diminution in yield will result.
3.
Without rocking, the crude product is colored and the yield is slightly lower.
4.
This is a total yield of material obtained in 2–3 crops. In a typical run the first crop amounted to
90 g., m.p.
44–45°, and the second, obtained on concentrating and cooling the mother liquor, amounted to
16 g., m.p.
44–45°.The crude product may alternatively be purified by rapid distillation at reduced pressure to give 114–116 g., b.p. 95–100°/1 mm. Redistillation affords 102–105 g. (83–86% yield), b.p. 96–98°/0.6 mm., of colorless 9-methylfluorene which solidifies.
5.
The submitters state that the procedure is general and has been carried out with normal alcohols from C
1 to C
7. In an analogous procedure
10 g. of fluorene was treated with 40 ml. of alcohol and
2.3 g. of sodium (in a
Carius tube) to give 52–84% of redistilled 9-alkylfluorene.
9-n-Octadecylfluorene was prepared from
13.3 g. of fluorene,
16.2 g. of n-octadecyl alcohol, and
2 g. of sodium. In this case the reaction was carried out in a flask (equipped with a condenser) that was heated in an
oil bath for 16 hours at 210°. The solid product was purified by crystallization.
|
|
Product
|
B.P./1 mm.
|
nD25
|
d425
|
Yield, %
|
|
|
9-Ethylfluorene
|
123–124°
|
1.6180
|
1.0508
|
84
|
|
9-n-Propylfluorene
|
126–128°
|
1.6050
|
1.0326
|
72
|
|
9-n-Butylfluorene
|
140°
|
1.5956
|
1.0197
|
78
|
|
9-n-Pentylfluorene
|
144–146°
|
1.5929
|
1.0153
|
66
|
|
9-n-Hexylfluorene
|
156–158°
|
1.5757
|
0.9900
|
68
|
|
9-n-Heptylfluorene
|
163–165°
|
1.5717
|
0.9827
|
58
|
|
9-n-Octadecylfluorene
|
65–66.4°(m.p.)
|
—
|
—
|
92
|
|
3. Discussion
Generally,
fluorene has been alkylated in the 9-position by reaction of 9-acyl- or ester-substituted fluorenes with sodium alkoxide and an alkyl halide followed by removal of the activating group, by treating a 9-fluorenyl organometallic compound with an alkyl halide, by reduction of a 9-fluorenylidene derivative, by hydrogenolysis of a 9-alkyl-9-hydroxyfluorene, by hydrogenolysis of a 9-halogen-9-alkylfluorene, and by cyclization of a diphenylalkylcarbinol with
phosphorus pentoxide.
2 The present procedure is based on the method of Shoen and Becker.
39-Methylfluorene has been prepared by cleavage of
ethyl 9-methyl-9-fluorenylglyoxylate,
4 by the decarboxylation of
9-methylfluorene-9-carboxylic acid,
4 by the decarboxylation of
9-fluorenylacetic acid,
5 by the cleavage of
9-methyl-9-acetylfluorene with alcoholic
potassium hydroxide or soda-lime,
6 by the reduction of
9-methyl-9-fluorenol with
hydriodic acid in acetic acid,
7 by the reaction of
9-fluorenyllithium8 or -sodium9 with
methyl iodide or
methyl sulfate,
9 by the cyclization of
diphenylmethylcarbinol over
platinum-on-carbon at 300°,
10 by the reaction of
ethyl 9-methoxymethyl-9-fluorenylcarboxylate,
11 by the diazotization and heating of
2-ethyl-2-aminobiphenyl,
12 by the dehydration and then reduction of
9-methyl-9-fluorenol,
13 by the thermal decomposition of
tetramethylammonium 9-fluorenide,
14 and by recovery from coal tar.
15
Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)
hydrochloric acid (7647-01-0)
acetic acid (64-19-7)
Benzene (71-43-2)
methanol (67-56-1)
platinum (7440-06-4)
carbon (7782-42-5)
potassium hydroxide (1310-58-3)
sodium (13966-32-0)
hydriodic acid (10034-85-2)
Methyl iodide (74-88-4)
methyl sulfate (75-93-4)
fluorene (86-73-7)
9-Methylfluorene,
Fluorene, 9-methyl- (2523-37-7)
9-Ethylfluorene (2294-82-8)
ethyl 9-methyl-9-fluorenylglyoxylate
9-methylfluorene-9-carboxylic acid
9-fluorenylacetic acid (6284-80-6)
9-methyl-9-acetylfluorene
9-methyl-9-fluorenol
9-fluorenyllithium
diphenylmethylcarbinol (1883-32-5)
ethyl 9-methoxymethyl-9-fluorenylcarboxylate
2-ethyl-2-aminobiphenyl
tetramethylammonium 9-fluorenide
phosphorus pentoxide (1314-56-3)
9-n-Octadecylfluorene
n-octadecyl alcohol (112-92-5)
9-n-Propylfluorene
9-n-Butylfluorene
9-n-Pentylfluorene
9-n-Hexylfluorene
9-n-Heptylfluorene
Copyright © 1921-, Organic Syntheses, Inc. All Rights Reserved