Fluorene 4-methyl

Favorskil rearrangement of 2-chloro-cyclohexanone, 39, 37 Ferric chloride, 36, 31 37, 77 Ferric nitrate hydrate, 39, 73 Ferrocene, 36, 31, 34 Ferrous chloride solution in tetrahy-drofuran, 36, 31, 34 Fischer indole synthesis, of 1,2-benzo-3,4-dihydrocarbazole, 30, 91 of 1,2,3,4-tetrahydrocarbazole, 30, 90 Flavone, 32, 72 Flavylium chloride, 32, 75 Flow meter, 34, 7 Fluorene, 34, 32 39, 44 Fluorene, 9-methyl-, 39, 43 9-Fluorenecarboxylic acid, 33, 37 o-Fluorobromobenzene, 39, 75... 

Benzo[/3]fluorene, methyl-11/-/-Benzo[t)]fluorene, 9-methyl-Benzo[c]fluorene, methyl-7/-/-Benzo[c]fluorene... 

Methyl benzophenone photoinitiator, UV-curing coatings 4-Benzoyl-4 -methyl diphenyl sulfide photoinitiator, UV-curing inks Benzoin isobutyl ether Fluorene Methyl benzilate... 

Many other catalysts have been introduced for the polymerization of propylene to produce a range of different structures ranging from isotactic, syndiotactic, to hemi-isotactic and isotac-tic/syndiotactic sequences. These include catalysts based on a bridged cyclopentadiene/fluorene methyl-substituted ligand framework that can alternate the substitution of ethylene and propylene in copolymers. 

Trimethylsilyl halides can also be used for analogous reactions with arenediazo-nium tetrafluoroborates, as shown by Keumi et al. (1989). These authors treated 2-fluorenediazonium tetrafluoroborate in A/,Af-dimethylformamide or -acetamide with trimethylsilylchloride, -bromide, or -iodide in the presence of an excess of N-chlorosuccinimide, Af-bromosuccinimide, or methyl iodide, respectively, at 60 °C (Cl, Br) or at room temperature (I). The yields of the 2-halofluorenes were good in addition fluorene, the product of hydro-de-diazoniation, was obtained, if the reaction was run in tetrahydrofuran/Af,7V-dimethylformamide mixtures. The mechanism of these reactions, as well as that of the corresponding azido-de-diazoniation, is uncertain (see also Secs. 10.2 and 10.7). 

The rates of chlorination of bridged biphenyls have also been measured and show the effect of coplanarity on reactivity. Second-order rate coefficients (104A 2) at 25 °C were fluorene (1,700), 9,10-dihydrophenanthrene (170), 1,2 3,4-di-benzocyclohepta-1,3-diene (9.70), 5-methyl-l,2 3,4-dibenzocyclohepta-l,3-diene... 

In order to smdy the effect of perturbation arising from spiro-conjugation on the chemical reactivities, in particular the facial selectivities, sterically unbiased dienes (96 and 97) based on fluorenes in spiro geometry have been synthesized [165]. These dienes react as Diels-Alder dienes with several dienophiles (maleic anhydride (MA), A-phenylmaleimide (PMI), A-phenyl-l,3,5-triazoUne-2,4-dione (PTD) and iV-methyl-l,3,5-triazoline-2,4-dione (MTD)). 

Hemoglobin is another heme-containing protein, which has been shown to be active towards PAH, oxidation in presence of peroxide [420], This protein was also modified via PEG and methyl esterification to obtain a more hydrophobic protein with altered activity and substrate specificity. The modified protein had four times the catalytic efficiency than that of the unmodified protein for pyrene oxidation. Several PAHs were also oxidized including acenaphthene, anthracene, azulene, benzo(a)pyrene, fluoranthene, fluorene, and phenanthrene however, no reaction was observed with chrysene and biphenyl. Modification of hemoglobin with p-nitrophenol and p-aminophenol has also been reported [425], The modification was reported to enhance the substrate affinity up to 30 times. Additionally, the solvent concentration at which the enzyme showed maximum activity was also higher. Both the effects were attributed to the increase in hydrophobicity of the active site. 

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...

Verevkin, S.P. (2004) Vapor pressure measurements on fluorene and methyl-fluorenes. Fluid Phase Equil. 225, 145-152. 

Ford et al. prepared l-methyl-9-(2-methyl-l-naphthyl)fluorene (53) in the hope that, if rotation were the true mechanism, the introduction of the 1-methyl group in the fluorene nucleus would raise the barrier by increasing the steric interaction in the transition state for rotation. They found that the barrier to rotation from the sc (S ) isomer to the ac (R ) isomer was 33.3 0.3 kcal/ mol at 166°C in hexachlorobutadiene. If this value is compared with the barrier of 9-(2-methyl-l-naphthyl)fluorene (54), 29.2 kcal/mol at 116°C, which was determined by Siddall and Stewart (93), it is clear that the introduction of the methyl group into the 1-position of the fluorene ring raises the barrier to rotation. 

It may be argued that direct comparison of the barrier of 9-(2-methyl-l-naphthyl)fluorene with that of 9-(2-bromomethyl-6-methylphenyl)fluorene is not fair, because the latter carries a bromine atom. However, the discussion just presented is valid because Saito and Oki (98) found the Arrhenius activation energy for rotation of 9-(2-bromomethyl-l-naphthyl)fluorene (57) for the process ap — sp... 

As Ford and associates pointed out (95), introduction of a methyl group into the 1-position of the fluorene group in 9-(l-naphthyI)fluorene raises the barrier. This effect was examined in several compounds. The barrier to rotation in l-methyl-9-( 1 -naphthyl)fluorene was 21.4 kcal/mol at 433 K, which is ca. 4 kcal/ mol higher than that in the parent compound (101). Introduction of a 1-methyl group into 9-(8-methyl-l-naphthyl)fluorene raised the barrier for the sc (S ) —> ac (/J ) process to 25.2 kcal/mol at 307 K. Thus it was possible to isolate the sc (S ) isomer (59). Another pair of enantiomers, ac (/ ), was isolated. The equilibrium constant was again very large, 33 in favor of ac (/ ) (100). 

This kind of consideration is supported by X-ray crystallographic data of sc (S )-l-methyl-9-(8-methyl-l-naphthyl)fluorene (59) (103). In this molecule, the C—C bond connecting the naphthyl and the fiuorene ring is not parallel with the CH3—C,-(naphthyl) bond, thus indicating that internal strain has accumulated. Even more strikingly, l-fluoro-9-(l-naphthyl)fluorene (62) has a lower... 

The first is the fact that these compounds have low barriers to rotation relative to the corresponding methyl or substituted methyl compounds. This is in line with the fact that 9-(2,6-dimethoxyphenyl)fluorene has a lower barrier than 9-mesitylfluorene (94). This must be again a reflection of the fact that the effective size of the oxygen is smaller than that of methyl. 

The foregoing examples of differential reactivities of rotamers may be summarized by saying that the reactivity is controlled by the steric factor. The difference in the reactivities of rotamers of 9-(2-bromomethyl-6-methyl-phenyl)fluorene (56) in SN2 type reactions falls in the same category (176). However, the substituent effect is not limited to a steric one there can be conformation-dependent electronic effects of substituents as well. A pertinent example is found in the reactivity of the bromomethyl compound (56) when the rotamers are heated in a trifluoroacetic acid solution (Scheme 10). The ap form gives rise to a cyclized product, whereas the sp form remains intact (176). The former must be reacting by participation of the it system of the fluorene ring. 

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