Fluorene-2-acetic acid

In 75 % aqueous acetic acid, the bromination of fluorene at 25 °C obeys second-order kinetics in the presence of bromide ion and higher orders in its absence287, with Ea (17.85-44.85 °C) = 17.4, log A = 10.5 and AS = —12.4 however, these values were not corrected for the bromine-tribromide ion equilibrium, the constant for which is not known in this medium, and so they are not directly comparable with the proceeding values. In the absence of bromide ion the order with respect to bromine was 2.7-2.0, being lowest when [Br2]initial was least. Second- and third-order rate coefficients were determined for reaction in 90 and 75 wt. % aqueous acetic acid as 0.0026 and 1.61 (k3/k2 = 619), 0.115 and 12.2 (k3/k2 = 106) respectively, confirming the earlier observation that the second-order reaction becomes more important as the water content is increased. A value of 7.25 x 106 was determined for f3 6 (i.e. the 2 position of fluorene). 

Figure 12.5 Pyrogram of Mowilith 30, a vinyl acetate polymer used in conservation. Peak assignments 1, acetic acid 2, benzene 3, styrene 4, indene 5, 1,2 dihydro naphthalene 6, naphthalene 7, 2 methyl naphthalene 8, 1 methyl naphthalene 9, biphenyl 10, fluorene 11, anthracene...

Derivatives of the general formula (7) in Table 6 have been successfully used as probases and their properties in this context are being further explored. In common with the azobenzenes and ethenetetracarboxylate esters, the fluoren-9-ylidene derivatives usually display two reversible one-electron peaks in cyclic voltammetric experiments. Although disproportionation is possible (cf. Scheme 12) it is the dianions which are the effective bases. It was shown early on that the radical-anions of such derivatives are long-lived in relatively acidic conditions (e.g. in DMF solution the first reduction peak of Ph C -.QCN) remains reversible in the presence of a 570-fold molar excess of acetic acid, at 0.1 V s ). Even the dianions are relatively weak bases, useful mainly for ylid formation from phosphonium and sulphonium salts (pKj s 11-15) they are not sufficiently basic to effect the Wittig-Homer reaction which involves deprotonation of phosphonate esters... 

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,6 by the cleavage of 9-methyl-9-acetyl-fluorene 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-fluorenyllithium 8 or -sodium 9 with methyl iodide or methyl sulfate,9 by the cyclization of diphenylmethyl carbinol over platinum-on-carbon at 300°,10 by the reaction of ethyl 9-methoxymcthyl-9-fluorcnylcarboxylate,11 by the diazotization and heating of 2-ethyl-2-aminobiphenyl,12 by the dehydration and then reduction of 9-mcthyl-9-fluorcnol,13... 

To a solution of the S-(+)-4-acethoxy-9-[2-(5-ethyl-l,2,3,6-tetrahydro-pyridin-3yl)-l-(lH-indol-2-yl)-l-methoxycarbonyl-ethyl]-3a-ethyl-5-hydroxy-8-methoxy-6-methyl-3a,4,5,5a,6,ll,12,12b-octahydro-lH-6,12a-diaza-indeno[7,l-ca]fluorene-5-carboxylic acid methyl ester in dioxane and glacial acetic acid was added 37% aqueous formaldehyde and the mixture stirred at 35°C for 24 h. The solution was evaporated in vacuo and the residue suspended in chloroform and washed with cold aqueous 5% K2C03 solution. The chloroform layer was dried (MgS04), filtered, and evaporated. The residue was chromatographed eluting with EtOAc/MeOH, 10% NH4OH to give the product navelbine. 

Cyclopropanation of the C=C bond of an allylic halide as in the cyclopropane 15 greatly suppresses photoreactivity, which is restored by introduction of a vinyl group at the 2-position of the cyclopropyl group, as in 16 (equation 27)134. The shift in UV-absorption maxima of 15 and 16 indicates the presence of electronic interactions of the vinyl and bro-momethyl moieties through the cyclopropane ring in 16. A similar arrangement of chro-mophoric moieties is present in compound 17, which on direct irradiation in acetic acid yields benzo[c]fluorene as sole product (equation 28)135. 

A warm solution of 600 g. of technical sodium dichromate in 800 ml. of glacial acetic acid and 200 ml. of water is added dropwise (30 minutes) to a rapidly refluxing solution of 200 g. (1.2 moles) of technical fluorene in 400 ml. of glacial acetic acid. The mixture is refluxed for an additional 2.5 hours, after which it is poured into 4 1. of ice water and allowed to stand for 2 hours. The precipitated solid is filtered off and washed first with dilute sulfuric acid then with water until free of chromate ion. The air-dried product (190-200 g.)... 

Fluorene (16.6 g., 0.10 mole) is dissolved in a hot solution of 4 g. (0.17 g. atom) of sodium in 200-250 ml. of absolute ethanol. The resulting solution is held at 60-70° while 12.0 g. (0.1 mole) of p-tolualdehyde dissolved in 100 ml. of ethanol is added. The mixture is allowed to stand several hours until the product has precipitated. The solid is removed by filtration and the filtrate is diluted with water for recovery of a second portion of solid product. The material is recrystallized from acetic acid or from ethanol to give 9- (4 -methyl-benzal)-fluorene, m.p, 97.5°. The yield is in the range 50-70. ... 

Diaryl ketones, such as o-bromobenzophenone and fluorenone carboxylic acids," are reduced by HI and red phosphorus in acetic acid or propionic acid under reflux, giving o-bromophenylphenyl-methane and fluorene carboxylic acid in high yields. 

Fluorene is oxidized to fluorenone in 65-70% yield by refluxing for 3 h with sodium dichromate in acetic acid [622], and 2-methylfluorene is converted into 2-methylfluorenone via its oxime on treatment with amyl nitrite (pentyl nitrite) [452]. The methylene group between two aromatic rings is oxidized in preference to the methyl group because nitrites react only with highly activated methylene groups (equation 177). 

Anthracene was oxidized to anthraquinone by warming a mixture of 90 g. of finely powdered hydrocarbon, 0.5 g. of vanadium pentoxide, 76 g. of sodium chlorate, 1 1. of acetic acid, and 200 ml. of 2% sulfuric acid under reflux until a vigorous reaction set in. After eventual brief refluxing, anthraquinone was obtained in 88-91% yield. The method is not suitable for the oxidation of hydrocarbons of the naphthalene or phenanthrene series to the quinones or for oxidation of acenaphthene or fluorene. 

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