Tetrabromophthalic Anhydride Research Articles

High temperature oxygen index studies of halogenated polyester thermosets containing antimony and molybdenum oxides

AbstractA study has been made of the effect of antimony and molybdenum oxides on the temperature‐critical oxygen index relationship of halogenated polyester thermosets. The polyesters were prepared from maleic anhydride, phthalic anhydride and propylene glycol, using either tetrachlorophthalic anhydride, tetrabromophthalic anhydride or chlorendic anhydride as the halogen source. Marked differences were observed in the effect of the two oxides. The critical oxygen index values of the halogenated polyesters containing maoybdenum (VI)oxide decreased with increase in timperature, which is in accordance with what is normally found for organic polymers, with and without additives. In contrast to this, the critical oxygen index values of the formulations containing antimony(II)oxide increased with increased with increase in temperature to reach a maximum value at around 100–150 °C. These results indicate that antimony(II)oxide is a better flame retardant than molybdenum(VI)oxide, since not only is it superior at the primary ignition stage but it shows enhanced activity at the higher temperatures which would be experienced by polymeric material in the early stages of a fire. It is concluded that higher temperature critical oxygen index studies provide a better guide to the flame retardant activity of additives than do ambient critical oxygen index determinations alone.

The chemistry of azides derived from N-substituted phthalamic and tetrahalogenophthalamic acids

Treatment of eight phthalisoimidium perchlorates with sodium azide gave N-substituted o-carbamoylbenzoyl azides (2), which yielded o-carbamoylphenyl isocyanates (4) when heated. The isocyanates derived from tertiary phthalamic acids formed 4-dialkyl ammonio-1,4-dihydro-2H-3,1-benzoxazin-2-one perchlorates (8) by the action of perchloric acid and acetic anhydride; those containing secondary amide groups cyclised to 3-alkyl-quinazoline-2,4-(1H,3H)-diones (11) at rates depending on the size of the alkyl radicals. Tetrachloro- and tetrabromo-phthalic anhydride reacted with amines to yield the corresponding amic acids, their salts, or N-substituted 3-amino-4-hydroxyphthalides. Ring-chain isomerism was also observed in the case of the azides derived from two tertiary tetrachlorophthalamic acids.

The i.r. and Raman spectra of tetrabromophthalic anhydride, tetrabromophthalimide, N-d-tetrabromophthalimide and potassium tetrabromophthalimide

The i.r. (4000-180 cm −1) and Raman (4000-40 cm −1) spectra of tetrabromophthalic anhydride, tetrabromophthalimide, N-d-tetrabromophthalimide and potassium tetrabromophthalimide have been investigated for polycrystalline compounds. The observed frequencies have been assigned tentatively on the basis of C 2ν molecular symmetry. A normal coordinate analysis has been carried out on an assumption of the valence force field and the CO stretching vibrations of OCXCO resonating system have been discussed using the obtained force constants.

On the origin of long-lived emission in some charge-transfer crystals

Temperature dependence of emission spectra, decay times and intensity of emission, for molecular (1:1) crystals of charge-transfer (CT) complexes of tetrachloro- and tetrabromophthalic anhydride with penta- and hexamethylbenzene, have been investigated over a wide temperature range (1.7–300 K). A long-lived emission, observed in those crystals, has been identified as CT phosphorescence from CT triplet traps. No delayed emission, controlled by triplet—triplet annihilation (P-type), has been found. An explanation of observations connected with the fact that these complexes belong to the class where the lowest triplet state is of charge-transfer character is offered.

Flame retardant polyesters based on bromine derivatives

AbstractUnsaturated polyesters containing halogens in the backbone of the polymer chain were synthesized. Derivatives used had brominated functional groups such as tetrabromobisphenol A, tetrabromophthalic anhydride, and dibromoneopentyl glycol. These were compared to chlorine‐containing polyesters based on HET acid and tetrachlorophthalic anhydride and an additive exhibiting a synergistic effect of phosphorus and halogen, trichloroethyl phosphate. Optical properties before and after artificial weathering (up to 1650 hr), were determined on cast specimens, and mechanical properties (flexural strength, modulus, and hardness) and flame retardancy were determined on glass fiber laminates. The flammability tests consisted of the “oxygen index” and the “self‐extinguishing time” tests, which were correlated for various halogen concentrations and different compositions. The efficiency of bromine in flame retardancy has been found to be much higher than that of chlorine. The minimal concentration of bromine required for self‐extinguishing is 10–12%, as compared with 20–25% for chlorine. A general performance index for polyesters has been derived which incorporates both flame and weather resistivity factors of the modified polyesters.

Combined Application of Reactive Compounds in Nonaqueous Swelling Solvents for Flame- and Shrink-Resistant Wool

A new way to produce wool that is both flame resistant and machine washable is by simultaneous treatment with tetrabromophthalic anhydride and tolylene diisocyanate in hot cresol. The treatment illustrates the combined application of wool-reactive compounds in nonaqueous swelling solvents for multiple benefits.

Topochemical Studies. VII. The Crystal and Molecular Structures of Tetrachlorophthalic Acid Hemihydrate and Tetrabromophthalic Anhydride

Abstract The crystal structures of tetrachlorophthalic acid hemihydrate (TCPH) and tetrabromophthalic anhydride (TBPA) have been determined from visually estimated CuKα data. The crystals of TGPH are monoclinic, space group A2/a, a=19.81(1), b=7.091(5), c=16.22(1) Å, β=101.2(2)° and Z=8. Those of TBPA are monoclinic, space group P21/n, a=13.39(3), b=6.19(2), c=12.66(3) Å, β=91.1(3)° and Z=4. The structures of TGPH and TBPA were solved from the sharpened Patterson maps, and refined by the block-diagonal least-squares method to R values of 0.112 and 0.112 for 1287 and 1278 non-zero reflections, respectively. The molecules of TCPH related by a twofold screw axis are linked together by hydrogen bonds between the carboxylic groups to form a chain along the b axis and the chains are held together by hydrogen bonds through water molecules to form a sheet parallel to the (100) plane. The sheets are stacked by van der Waals forces. The dihedral angles of the carboxylic groups with the benzene ring are 68.2 and 48.9°. The crystals of TBPA are isomorphous to those of tetrachlorophthalic anhydride. The benzene ring of TBPA are distorted by the attachment of five membered ring. There is considerable molecular overlap in TCPH, while in TBPA there is no overlap.

Dyebath Application of Flame Retardants for Flame-Resistant Wool1

Tetrabromophthalic anhydride and tetrabromophthalic acid can effectively flameproof a wide range of wool textile materials, e.g., hand-knitting yarn, carpet yarn, and airplane upholstery, when applied during the dyeing step. In addition, the treatment can be utilized on wool-nylon blends as well as all-nylon fabrics. Fabrics treated with these reagents, when heated, do not turn brown so readily as fabrics treated with certain other flame-retarding agents. Treated fabrics retain normal softness, are not irritating to the skin, and retain flame resistance after dry cleaning and gentle washing.

Tetrabromophthalic anhydride in self‐extinguishing polyesters

AbstractPolyesters based on tetrabromophthalic anhydride are self‐extinguishing in the range of 8–12% bromine content and nonburning at higher levels of the latter. An increase in bromine content results in higher flexural and tensile strenght and flexural modulus, while impact resistance is slightly reduced. Mechanical Properties vary with bromine content in the 0–12% range and remain practically unaffected at higher levels up to 23%.

Charge transfer interaction between tetrabromophthalic anhydride and aromatic hydrocarbons

A spectro-photometric study on charge transfer complexes of totrabromophthalic anhydride with various hydrocarbons has been made in chloroform and benzene. In each case charge transfer bands characteristic of the formation of 1 : 1 complexes have been observed. Equilibrium constant K c and extinction coefficient ε c for each of the complexes have been calculated from the spectrophotometric data. Various predicted regularities have been tested in the light of these results.

Energy Transfer in Charge-Transfer Complexes. III. Intersystem Crossing

The quantum yield ratio of phosphorescence to fluorescence, φp/φf, of the donor component has been investigated for charge-transfer complexes of naphthalene, phenanthrene, and acenaphthene with the acceptors sym-trinitrobenzene, 2,4,7-trinitrofluorenone, tetrachlorophthalic anhydride, tetrabromophthalic anhydride, and tetra-iodophthalic anhydride. It is shown that φp/φf increases for fixed donor concentration as the concentration of the acceptor increases, and that the value of φp/φfΞy″ of the complexed emitter may be deduced from the observed rate of increase of φp/φf. By this means it is shown that complexing with sym-trinitrobenzene increases the quantum yield ratios of naphthalene and acenaphthene by factors of approximately 30 and 75, respectively. An increase of approximately 103 is observed upon complexation with the tetrahalophthalic anhydrides, and a heavy-atom effect is distinctly manifested within the anhydride series. It is possible to bracket values of the intersystem rate constant, ki, whence it is shown that in charge-transfer complexes the increase in the intersystem crossing probability makes it an important fluorescence quenching mode. It is also shown that the intersystem crossing process is significantly more sensitive to complexation and heavy-atom effects than the phosphorescence emission or quenching processes. The observed effects are briefly discussed in terms of conventional theories. Charge-transfer fluorescence of some crystalline complexes at room temperature is described, and the mirror-image relationship to the charge-transfer absorption shown by Czekalla et al. is verified. Finally, some thermodynamic data for the investigated complexes are presented, and from the behavior of extinction coefficient and stability of the complexes as a function of λmax of the charge-transfer bands it is inferred that the charge-transfer band borrows much of its intensity from transitions proper to the donor.