Fluorine compounds, derivatives

A MINDO/3 method has been used to calculate the electronic structure of polyethylene,127 and comparison has been made with the photoelectron spectrum. Extended Huckel calculations on six fluorinated compounds derived from linear polyethylene have been carried out with the same objective.128 The circular dichroism of unordered polymers has been treated on the basis of time-dependent Hartree theory,129 130 131 and high-resolution inelastic tunnelling spectroscopy of macromolecules has been reported.180... 

The most important of the halogenated derivatives of acetic acid is chloroacetic acid. Fluorine, chlorine, bromine, and iodine derivatives are all known, as are mixed halogenated acids. For a discussion of the fluorine derivatives see Fluorine compounds, organic. 

The equimolar copolymer of ethylene and tetrafluoroethylene is isomeric with poly(vinyhdene fluoride) but has a higher melting point (16,17) and a lower dielectric loss (18,19) (see Fluorine compounds, organic-poly(VINYLIDENE fluoride)). A copolymer with the degree of alternation of about 0.88 was used to study the stmcture (20). Its unit cell was determined by x-ray diffraction. Despite irregularities in the chain stmcture and low crystallinity, a unit cell and stmcture was derived that gave a calculated crystalline density of 1.9 g/cm. The unit cell is befleved to be orthorhombic or monoclinic (a = 0.96 nm, b = 0.925 nm, c = 0.50 nm 7 = 96%. 

The aluminum halides and aluminum nitrates have similar properties with the exception of the family of aluminum fluoride compounds which are discussed elsewhere (see Fluorine compounds, inorganic). Of the remaining members ia this aluminum haUde family, chloride derivatives are the most commercially important alurniaum brornide /7727-/3 -JJ AlBr, alumiaum iodide [7784-23-8] and alumiaum nitrate [13473-90-0] are of... 

Release agents function by either lessening intermolecular interactions between the two surfaces in contact or preventing such close contact. Thus, they can be low surface-tension materials based on aUphatic hydrocarbon, fluorocarbon groups, or particulate soHds. The principal categories of material used are waxes, fatty acid metal soaps, other long-chain alkyl derivatives, polymers, and fluorinated compounds. 

Fluorination of naphthalene in a stream of dilute fluorine over cobalt trifluoride yields a mixture of perfluorodecalins and partially fluorinated naphthalene derivatives that are fully fluorinated to perfluorodecalins by a subsequent treatment with dilute fluorine [23] Perfluorodecalins are also final products ot fluorination of tetralin over cobalt trifluoride at 250 °C. A more thorough investigation of this reacPon revealed seven additional compounds as products and intermediates [//] (equation 6). 

The preparation of aromatic fluorine compounds may be accomplished by direct fluorination or by fluonnation of organometallic intermediates. Tlte ipso fluorination of an aryl organometallic derivative with a positive fluorine reagent allows control over the regioselectivity of the fluorination and offers advantages in the preparation of F-labeled materials [II, 50],... 

Certain fluorine compounds may be used to dehydrate nonfluorinated alcohols through their complexes or derivatives With aleohols, 1,1,1-trichlorotri-fluoroacetone forms intermediate hemiketals that easily decompose to olefins in the presence of a catalytic amount of p toluenesulfomc acid [S5] Similarly, the... 

A C60 derivative with an attached fluorinated chain gave a limiting area of 0.78 nm molecule [266]. It was reported that this film was so mechanically rigid that it pushed the Wilhehny plate out of the water at 11 14 mN m The monolayer spreading of this compound arises from the even greater hydrophobicity of the fluorocarbon chains and their orientation away from the water surface. The LB films with a fluorinated tetrathiafulvalene derivative did not show evidence of charge transfer in their UV spectra. 

A comprehensive review of the preparation, reactions, and n.m.r. spectra of phosphorus-fluorine compounds has appeared. This year s literature has been notable for the first detailed applications of ab initio SCF-MO calculations to the problems of bonding in halogenophosphines and their derivatives. - Comparison of the results of such theoretical calculations with experimental data obtained from photoelectron spectra shows a good correlation in the case of phosphorus trichloride and phosphoryl chloride, and of phosphorus trifluoride and its borane complex. ... 

It is possible to synthesize alkylcobalamins containing halogenated alkyl groups. Of these, the compounds studied most extensively are the halo-methylcobalamins (745). For the various fluorine containing derivatives which have been prepared, 19F NMR spectra have been obtained and the results are shown in Table 6. Chemical shifts of a number of fluorome-thanes are included for comparison. 

These highly fluorinated homopolymers (7,8) derived from hydroxy fluor-ovinyl ethers (5,6), in contrast to typtical highly fluorinated compounds and polymers, exhibit unusually good solubility in common organic solvents. The NMR chemical shifts of residual protons in these polymers are highly sensitive to the polarity of the solvent as shown in Table 4.3. 

No direct comparison of the fluorinated castanospermine derivatives with the corresponding 1-deoxynojirimycin analogues has yet been conducted. In the castanospermine series, the fluorinated compounds exhibited low inhibitory activities. Only the 6-deoxyfluoro derivative 86 (corresponding to the 2-deoxyfluoro compound... 

OrganometaUoidal Fluorine Compounds. Part III. Trifluoromethyl Derivatives of Sulphur. J. Chem. Soc. 1952, 2198. 

Trifluorothreonine is one of the rare fluorinated compounds found in nature (cf. Chapter 4). The best method for the synthesis of fluorothreonines is the acylation of an equivalent of glycinate anion by a fluoroacetic derivative. The four stereoisomers of monofluorothreonine have been prepared. A completely stereoselective chiral approach involves the alkylation of the Seebach imidazolidinone by fluoroacetyl chloride (Figure 5.16). ... 

From the study of a microbially mediated oxidation of arteether 28b, sufficient quantities of 7a-hydroxy 180 and 15-hydroxy derivatives 182 were obtained to employ them as intermediates for the preparation of fluorinated compounds. The hydroxyl groups were oxidized to the corresponding aldehyde 187, or ketone 188, with catalytic quantities of tetra- -propylammonium perruthenate (TPAP) in the presence of excess iV-methylmorpholine A -oxide. On reaction with DAST, 187 and 188 were converted into the corresponding geminal difluoro derivatives, 189 (63%) and 190 (42%). In addition to 190, a monofluoro olefin 191 was obtained in 25% yield from 188 on reaction with DAST <1995JME4120>. 

A reaction which has some resemblance to this nitroso decarboxylation is the pyrolytic or photolytic decarboxylation of fluorinated nitrites (Eqs. 24 and 25) [63]. The nitroso compounds derived from these nitrite esters appear... 

They could be trapped with a variety of electrophiles such as aldehydes, water, carbon dioxide, trimethylsilyl chloride, tributyltin chloride to give the corresponding difluorovinyl derivatives [132-138] (Scheme 52), which were demonstrated to be versatile and useful building blocks for the synthesis of organo-fluorine compounds. 

Detailed analyses of partially fluorinated compounds from the ECF of amines, and relatively simple sulphonic acid derivatives have been performed with interesting and illuminating results but do these observations translate into other complex systems, e. g., long chain carboxylic acid derivatives The experiments have yet to be done. 

Kinetically controlled conditions favor the formation of mixed fluorinated compounds if per-halo derivatives are fluorinated with hydrogen fluoride. Therefore, catalysts or coreagents are used to overcome this problem. Thus, selective fluorination of l,3-bis(trichloromethyl)benzene cannot be achieved by hydrogen fluoride using variations in temperature, pressure or time.247 However, if antimony(V) fluoride is added to hydrogen fluoride the reaction produces l-(tri-chloromethyl)-3-(trifluoromethyl)benzene. Selective fluorination can also be performed in compounds with different substitution patterns.247,251 253... 

Apart from fragmentations, the main byproducts isolated are partially fluorinated compounds in which the remaining hydrogen atoms are attached to the most hindered carbon as demonstrated in the case of di-tert-butylmethane (l)11 and in the preparation of dimethyl bexa-fluorobicyelo[1.1.1]pentane-l,3-dicarboxylate(2, R = F). Apart from the perfluorinated products considerable amounts of polyfluoro derivatives are also obtained.12... 

Further examples are found in references 196 and 197. Tetrabutylammonium fluoride (TBAF) has found many applications in synthesizing several fluoro derivatives via nucleophilic substitution on the appropriate substrates. Organo-fluorine compounds are not only interesting as medicinal drugs, but they are also useful as technical products. 

---