2- -9//-fluorene

Fluorene was discovered in coal tar, in which it is present in amounts of around 2%, by Pierre M. Berthelot in 1867. 

It is recovered by redistillation of the fluorene oil fraction, which boils between 290 and 305 °C (or from the distillation fore-runnings in anthracene production), followed by recrystallization, for example, from solvent naphtha. Technical fluorene, 95% pure, is commonly used to produce fluorenone by liquid-phase oxidation with air/oxygen at around 100 °C. Fluorenone can principally be used as a mild oxidant for Oppenauer oxidation, particularly in steroid chemistry. 

3 Fluorene. This is an example of a bridged biphenyl hydrocarbon. The action of chlorosulfonic acid and sulfuric acid on fluorene 39 results in substitution mainly at the 2- and 7-positions thus the action of chlorosulfonic acid (one equivalent) gives the 2-sulfonic acid while excess of the reagent affords 2,7-disulfonic acid.  

A similar orientation of sulfonation was found in the reaction of 9-alkylfluorenes and 9,9 -spirofluorene these positions are para with respect to the bridge bond, so the substitution orientation is analogous to that of biphenyl itself 

Cremlyn et aV examined the reaction of fluorene 39 with excess chlorosulfonic acid (six or twelve equivalents) or less reagent (three equivalents) in thionyl chloride. In each case, the product appeared to be a 1 1 mixture of the 2-sulfonyl chloride and the 2,7-disulfonyl chloride. The latter compoimd was obtained as the major product when fluorene-9-carboxylic acid was treated with a large excess of chlorosulfonic acid (twelve equivalents) in boiling chloroform (2 hours).  

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Fluorene can be nitrated, sulphonated and chlorinated. Oxidation gives fluorenone (9 O). 

The series of compounds biphenyl, diphenylmethane, and fluorene is an interesting one. The following diagrams give the partial rate factors ... 

These partial rate factors have been recalculated from the experimental data of Dewar and Urch. Their reported values for diphenylmethane are not seriously discrepant with the values now given, but this is not so for the values for fluorene. As given, and copied in the literature, the values were /j = 2040 / = 60 fi = 944. There are consequent errors in table 8 and figs. 16 (reproduced as fig. 9. i of this volume) and 32 of ref. 22. 

FLUORINECOMPOUNDS,ORGANIC - FLUOROETTiERS AND FLUOROAMINES] (Vol 11) 4(9H-Fluoren-9-ylidenemethyl)-N,N-bis(methylphenyl)benzenamine [ql[115838-15-8]... 

Eused-ring polycycHc fluoroaromatics can be made from the corresponding amino fused-ring polycycHc or from preformed fluoroaromatics, eg, 4-fluorophenyl-acetonitrile [459-22-3] (275). Direct fluorination techniques have been successfully appHed to polycycHc ring systems such as naphthalene, anthracene, benzanthracenes, phenanthrene, pyrene, fluorene, and quinoHnes with a variety of fluorinating agents xenon fluorides (10), acetyl hypofluorite (276), cesium fluoroxysulfate (277), and electrochemical fluorination (278,279). 

All lation of Garbanions. Concentrated N a OH—hen syl triethyl amm onium chloride is the base/catalyst system normally used for this type of process (20). Classes of compounds alkylated in this way include phenylacetonitriles, ben2ylketones, simple aUphatic ketones, certain aldehydes, aryl sulfones, P-ketosulfones, P-ketoesters, malonic esters and nitriles, phenylacetic esters, indene, and fluorene (see Alkylation). 

Polymerization. CPD dimerizes spontaneously and exothermically at ambient temperature to DCPD. At temperatures above 100°C, CPD can be made to polymerize noncatalytically via a series of consecutive Diels-Alder reactions to trimer, tetramers, and higher oligomers. Eor example, the trimers, 3a,4,4a,5,8,8a,9,9a-octahydro-4,9 5,8-dimethanobenz-lJT-[ iQdene, [7158-25-0] (3) and l,4,4a,4b,5,8,8a,9a-octahydro-l,4 5,8-dimethano-lJT-fluorene [35184-08-8] (4), are formed ia the ratio 87 13 by the monomer adding to the dimer (19). 

As might be anticipated from the behaviour of the parent heterocycles, C-2 of indole, benzo[i]furan and benzo[i]thiophene (Table 13) is shifted to lower field than C-3. However, the shifts for C-2 (O, 144.8 Se, 128.8 S, 126.1 NH, 124.7 Te, 120.8) and C-7a (O, 155.0 Se, 141.3 S, 139.6 NH, 135.7 Te, 133.0) in the benzo[i] heterocycles vary irregularly (80OMR(l3)3l9), and the sequence is different to that observed for C-2 in the parent heterocycles, namely 0>Se>Te>S>NH. Also noteworthy is the upheld position of C-7, especially in indole and benzofuran, relative to the other benzenoid carbons at positions 4, 5 and 6. A similar situation pertains in the dibenzo heterocycles (Table 14), where not only are C-1 and C-8 shifted upheld in carbazole and dibenzofuran relative to the corresponding carbons in dibenzothiophene and fluorene, but similar, though smaller, shifts can be discerned for C-3 and C-6 in the former compounds. These carbon atoms are of course ortho and para to the heteroatom and the shifts reflect its mesomeric properties. Little variation in the carbon-hydrogen coupling constants is observed for these dibenzo compounds with V(qh) = 158-165 and V(c,h) = 6-8 Hz. 

Photolysis of spiro[fluorene-9,3 -indazole] (384) to the tribenzopentalene (385) has been rationalized in terms of the initial formation of triplet diradical (386) (76JOC2120). The spiroindazole (387) behaves differently and on irradiation in THF is converted into the dimer (388) and the stable iV-ylide (389) (76CB2596). 

H-2, 2 -Spirodibenzo-1,3,2-dioxaphosphole synthesis, 1, 522 Spiro[fluorene-9,3 -indazole] photolysis, 5, 252... 

Fluoranthene (ben2o[/,A ]fluorene) [206-44-0] M 202.3, m 110-111°. Purified by chromatography of CCI4 solns on alumina, with benzene as eluent. Crystd from EtOH, MeOH or benzene. Purified by zone melting. [Gorman et al. J Am Chem Soc 107 4404 1985.]... 

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