Excess Bromine Research Articles

Obtaining the Iodine Value of Various Oils via Bromination with Pyridinium Tribromide

A laboratory exercise was devised that allows students to rapidly and fairly accurately determine the iodine value of oleic acid. This method utilizes the addition of elemental bromine to the unsaturated bonds in oleic acid, due to bromine’s relatively fast reaction rate compared to that of the traditional Wijs solution method. This method also uses pyridinium tribromide as a bromine source in an effort to eliminate many of the safety hazards of working with elemental bromine. After the addition of a known quantity of bromine to the reaction flask, excess bromine is reduced with potassium iodide forming elemental iodine. The elemental iodine is then titrated with sodium thiosulfate and a starch indicator in a back-titration to determine the amount of excess bromine added to the oleic acid. Students then determine the iodine value of oleic acid by using a 126 g iodine/80 g of bromine ratio. This exercise can yield results fairly close to the accepted iodine value of 90 for oleic acid, as several of the gro...

Bromometric Estimation of Gliclazide and Glibenclamide in Bulk and in tablet Formulation.

Two spectrophotometric methods described for determination of, Gliclazide and Glibenclamide in bulk and pharmaceutical dosage forms using insitu generated bromine as oxidizing agent and either methylene blue or methyl orange as chromogenic agents. Drugs are treated with known excess of bromine and residual unreacted bromine is determined by treating with fixed amount of either methylene blue or methyl orange then measuring absorbance at 669 nm and 508 nm, respectively. The amount of bromine reacted corresponds to the amount of each drug. Effects of acidity, bromate - bromide volume and reaction time, on the absorption were studied. Calibration curves were linear over ranges of 3–10 μg.ml-1 for Gliclazide, 4- 24 μg.ml-1 for Glibenclamide in case of methylene blue and of 2–6 μg.ml-1 for Gliclazide, 4-12μg.ml-1 for Glibenclamide in case of methyl orange. The methods were validated and satisfactory applied for the determination of drugs in both bulk and in tablet form and results were compared statistically with reported methods.

The chemical behavior of terminally tert-butylated polyolefins.

The chemical behavior of various oligoenes 2 has been studied. The catalytic hydrogenation of diene 3 yielded monoene 4. Triene 7 was hydrogenated to diene 8, monoene 9 and saturated hydrocarbon 10. Bromine addition to 3 and 7 yielded the dibromides 17 and 18, respectively, i.e., the oligoene system has been attacked at its terminal olefinic carbon atoms. Analogously, the higher vinylogs 19 and 20 yielded the 1,8- and 1,10-bromine adduts 23 and 24, respectively, when less than 1 equivalent of bromine was employed. Treatment of tetraene 19 with excess bromine provided tetrabromide 25. In epoxidation reactions, both with meta-chloroperbenzoic acid (MCPBA) and dimethyldioxirane (DMDO) two model oligoenes were studied: triene 7 and tetraene 19. Whereas 7 furnished the rearrangement product 31 with MCPBA, it yielded the symmetrical epoxide 32 with DMDO. Analogously, 19 was converted to mono-epoxide 33 with MCPBA and to 34 with DMDO. Diels–Alder addition of 7 with N-phenyltriazolinedione (PTAD) did not take place. Extension of the conjugated π-system to the next higher vinylog, 19, caused NPTD-addition to the symmetrical adduct 37 in good yield. Comparable results were observed on adding NPTD (equivalent amount) to pentaene 20 and hexaene 21. Using 36 in excess provided the 2:1-adduct 40 from 21 and led to a complex mixture of adducts from heptaene 22. With tetracyanoethylene (TCNE) as the dienophile, tetraolefin 19 yielded the symmetrical adduct 43, although the reaction temperature had to be increased. Pentaene 20 and hexaene 21 led to corresponding results, adducts 44 and 45 being produced in acceptable yields. With nonaene 42 and TCNE the 2:1-adduct 48 was generated according to its spectroscopic data. Exploratory photochemical studies were carried out with tetraene 19 as the model compound. On irradiation this reacted with oxygen to the stable endo-peroxide 52.

Highly Sensitive and Validated Spectrophotometric Technique for the Assay of Some Antidepressant Drugs

The present paper describes a simple, rapid, reproducible, and highly sensitive spectrophotometric method for the determination of the tricyclic antidepressant drugs: amitriptyline hydrochloride (AMT), imipramine hydrochloride (IMH), clomipramine hydrochloride (CPH) and desipramine hydrochloride (DPH) in pure and in pharmaceutical preparations. The method is based on the bromination of the above drugs with known excess of bromine. The unreacted bromine is determined based on its ability to bleach the dye methyl red quantitatively at 520 nm. Regression analysis of Beer–Lambert plots showed a good correlation in the concentration range 0.0–2.5, 0–1.4, 0–1.4, and 0–1.0 μg/ml for AMT, IMH, CPH, and DPH, respectively. The molar absorptivity values were found to be 0.65 × 105, 1.41 × 105, 1.93 × 105, and 2.96 × 105l/mol/cm, with the corresponding Sandell’s sensitivity values were 0.0048, 0.0022, 0.0018, and 0.0010 μg/cm2 for AMT, IMH, CPH, and DPH, respectively. The limits of detection (LOD) and quantification (LOQ) are also reported for the developed method. Intra- and inter-day accuracy and precision was established according to the current ICH guidelines. Application of the procedure to the analysis of various pharmaceutical preparations gave reproducible and accurate results. Further, the validity of the proposed method was confirmed by applying the standard addition technique, and the results obtained are in good agreement with those obtained by the official method.

Cyclization of thioureas from the series of 4-aryl(hetaryl)spinaceamines

Reaction of allylthiocarbamoyl fragment of N-allylthioureas with excess bromine or iodine leads to the formation of 5-halomethyldihydrothiazole ring as confirms the dehydroiodination of the 5-(5-iodomethyl-4,5-dihydro-1,3-thiazol-2-yl)-4-phenyl-4,5,6,7-tetrahydro-1H-imidazo[4,5-c]pyridine with the formation of a 5-methylthiazole ring. The reaction of allylthiourea with hydrochloric acid affords a 5-methyldihydrothiazole ring.

ANTIDEPRESSANT DRUGS: HIGHLY SENSITIVE AND VALIDATED SPECTROPHOTOMETRIC TECHNIQUE

A simple, rapid, selective and highly sensitive spectrophotometric method is described for the quantitative determination of the tricyclic antidepressant drugs, desipramine hydrochloride (DPH), clomipramine hydrochloride (CPH) and imipramine hydrochloride (IMH) in pure and in pharmaceutical preparations. The proposed method is based on the bromination of above drugs with known excess of bromine. The unreacted bromine is determined based on its ability to bleach the dye Eiochrome blue black R quantitatively at 530 nm for all the three drugs obeying Beer’s law in the range, 0.0 – 8, 0.0 – 10 and 0.0 – 9.0 µg ml-1 for DPH, CPH and IMH, respectively. The molar absorptivity values were found to be 1.61 × 104, 1.62 × 104 and1.57 × 104 l mol-1cm-1, respectively with the corresponding Sandell’s sensitivity values 0.0187, 0.0216 and 0.0202 µg cm-2. The limits of detection and (LOD) and quantification (LOQ) are also reported for the developed method. Intra- and inter-day precision and accuracy of the method were established according to the current ICH guidelines. Applications of the procedure to the analysis of various pharmaceutical preparations gave reproducible and accurate results. Further, the validity of the procedure was confirmed by applying the standard addition technique and the results were evaluated in terms of Student’s t-test and variance ratio F-test to find out the significance of proposed method over the reference method.

Synthesis and Reactions of Triptycene‐Derived Bromocalix[5]arenes: Conformational Transformation from Cone to 1,2‐Alternate

AbstractTriptycene‐derived p‐dibromocalix[5]arene was synthesized by a fragment‐coupling approach, whereas treatment of the triptycene‐derived calix[5]arene containing three p‐tert‐butyl phenol groups and a 1,8‐dimethoxytriptycene moiety with excess bromine in dichloromethane at room temperature produced triptycene‐derived p‐pentabromocalix[5]arene directly. Methyl etherification and Suzuki coupling reactions were then carried out. As a result, a series of triptycene‐derived calix[5]arene derivatives in fixed cone and 1,2‐alternate conformations were obtained. Moreover, conformation transformations of triptycene‐derived calix[5]arenes from cone to 1,2‐alternate forms could also be achieved.

Analysis of Vitamin C (ascorbic acid) Contents packed fruit juice by UV-spectrophotometry and Redox Titration Methods

Total vitamin C (ascorbic acid + dehydroascorbic acid) has been determined by UV- spectrophotometric method in various fruit juices. In this method, a blended sample is homogenized with 3% metaphosphoric acid-10% acetic acid solu'an. Then addition of bromine water oxidizes ascorbic acid to dehydroascorbic acid in presence of acetic acid and the excess of bromine is removed by a few drops of 10% thiourea. After coupling with 2,4-dinitrophenyl hydrazine at 37°C temperature for three hours, the solution is cooled in an ice bath and is treated with chilled 85% H2SO4 to produce a red colour complex and the absorbance is measured spectrophotometrically at 521 nm. This method obeyed Beer's law as was tested by using a standard ascorbic acid. Also ascorbic acid can be determined by redox titration. We performed an iodimetric back-titration in which we generated a measured excess of iodine in the sample solution and then we titrated the unreacted iodine with a standard sodium thiosulfate solution. Our purpose is to determine the Vitamin C content in some packed (industrial) fruit juices and compare the values with that labeled on the packed fruit juices. The samples were collected from different markets in Benghazi.Such as Rhyhan, Mazraa, Judi, Alhanaa, Nadic, Viva, Rani, Bravo, Suntop, and Stantal of different kinds.

4-HYDROXY-2-QUINOLONES. 204. SYNTHESIS, BROMINATION, AND ANALGETIC PROPERTIES OF 1-ALLYL-4-HYDROXY-6,7-DIMETHOXY-2-OXO-1,2-DIHYDROQUINOLINE-3-CARBOXYLIC ACID ARYLALKYLAMIDES

A simple method has been proposed and used for the preparation of 1-allyl-4-hydroxy-6,7-dimethoxy-2-oxo-1,2-dihydroquinoline-3-carboxylic acid arylalkylamides. Similar to alkylamides of this acid, the arylalkylamides obtained are halogenated with cyclization by one equivalent of molecular bromine to give the corresponding 2-bromomethyl-7,8-dimethoxy-5-oxo-1,2-dihydro-5 H -oxazolo[3,2- a ]quinoline-4-carboxamides. However, the reaction proceeds quite differently when using an excess of bromine. After the usual initial oxazole ring closure, the excess bromine brominates the aromatic ring of the amide fragment. The results of testing for the analgesic activity of these products are presented. Authors: I. V. Ukrainets, E. V. Mospanova, N. A. Jaradat, O. V. Bevz, and A. V. Turov English Translation in Chemistry of Heterocyclic Compounds, 2012, 48 (9), pp 1347-1356 http://link.springer.com/article/10.1007/s10593-012-1143-7

Bromatometric Estimation of Cefepime, Cefoperazone, Cefotriaxone and Captopril in Bulk and Dosage Forms

Two spectrophotometric methods are described for determination of Cefepime, Cefoperasone and Cefotriaxone in bulk and pharmaceutical dosage forms using in situ generated bromine as oxidizing agent and either methylene blue or methyl orange as chromogenic agents. Drugs are treated with known excess of bromine and residual unreacted bromine is determined by treating with fixed amount of either methylene blue or methyl orange then measuring absorbances at 678 nm and 510 nm, respectively. The amount of bromine reacted corresponds to the amount of each drug. Effect of acidity, bromate – bromide volume and reaction time, on the absorption was studied. Calibration curves were linear over ranges of 1-3 µg.ml-1 for Cefepime,0.4- 1.0 µg.ml-1 for Cefoperazone and 0.3-0.8 µg.ml-1 for Cefotriaxone in case of methylene blue and of 0.05–3.0 µg.ml-1 for Cefepime, 0.75-2.0µg.ml-1 for Cefotriaxone in case of methyl orange. The for Cefoperazone and 0.2-1.4 µg.ml-1 methods were satisfactory applied for the determination of drugs in both bulk and pharmaceutical forms and results were compared statistically with reference methods.

4-hydroxy-2-quinolones. 204.* synthesis, bromination, and analgetic properties of 1-allyl-4-hydroxy- 6,7-dimethoxy-2-oxo-1,2-dihydroquinoline-3-carboxylic acid arylalkylamides

A simple method has been proposed and used for the preparation of 1-allyl-4-hydroxy-6,7-dimethoxy-2-oxo-1,2-di-hydroquinoline-3-carboxylic acid arylalkylamides. Similar to alkylamides of this acid, the arylalkylamides obtained are halogenated with cyclization by one equivalent of molecular bromine to give the corresponding 2-bromomethyl-7,8-dimethoxy-5-oxo-1,2-dihydro-5H-oxazolo[3,2-a]quinoline-4-carbox-amides. However, the reaction proceeds quite differently when using an excess of bromine. After the usual initial oxazole ring closure, the excess bromine brominates the aromatic ring of the amide fragment. The results of testing for the analgesic activity of these products are presented.

ChemInform Abstract: Structural Proof for a Higher Polybromide Monoanion: Investigation of [N(C3H7)4][Br9

Abstract[Pr4N][Br9] is synthesized by the reaction of [Pr4N]Br and excess bromine (20 °C, several days) and characterized by single crystal XRD, IR and Raman spectroscopy, conductivity measurements, and quantum chemical calculations at various levels of DFT and at ab initio HF, MP2, SCS‐MP2, SOS‐MP2, CCSD, and CCSD(T) level.

Influence of chloride and bromate interaction on oxidative stress in carrot plants

Since bromine is toxic to plants and humans, understanding plant responses to excess bromine is essential, and there is a need to know possible physiological mechanisms for the avoidance of Br-induced stress. Therefore, we investigated bromine-induced oxidative stress in carrot under glasshouse conditions in response to application of bromate and chloride. Five levels of Br (0, 0.125, 0.25, 0.50 and 1.00mmolkg−1 as KBrO3) and three levels of Cl (0, 10 and 20mmolkg−1 as KCl) were applied to soil-grown plants. Shoot dry weight of carrot was reduced with the highest level of applied Br, and both shoot and storage root dry weights were also reduced by the applied Cl. Low rates of application of Br gave higher total chlorophyll and carotenoid concentrations, but higher levels of applied Br significantly reduced both total chlorophyll and carotenoids. Accumulation of malondialdehyde (MDA, an indicator of lipid peroxidation) and H2O2 was significantly increased by Br treatments, as were activity of the antioxidant enzymes catalase (CAT) and ascorbate peroxidase (APX). There was no clear change in activity of superoxide dismutase (SOD) in response to Br. Chloride treatments did not appear to lower the activity of the antioxidant enzymes, but gave increased concentrations of H2O2 (although not MDA). Total bromine concentrations of the shoots and storage roots were significantly increased by increasing levels of Br supply, although Cl supply noticeably decreased them. Based on the present work, it can be concluded that applied Br caused oxidative stress and membrane damage in carrot plants. However, applied Cl levels in this work did not prevent oxidative damage, but significantly reduced Br concentrations in the shoots and storage roots.

Structural Proof for a Higher Polybromide Monoanion: Investigation of [N(C3H7)4][Br9

[Pr4N][Br9] is synthesized by the reaction of [Pr4N]Br and excess bromine (20 °C, several days) and characterized by single crystal XRD, IR and Raman spectroscopy, conductivity measurements, and quantum chemical calculations at various levels of DFT and at ab initio HF, MP2, SCS-MP2, SOS-MP2, CCSD, and CCSD(T) level.

Selective bromination of dihydroquinopimaric acid

The reaction of dihydroquinopimaric acid methyl ester with bromine was found to be chemo- and stereoselective. Regardless of the solvent (acetic acid, methanol, dioxane), bromination of the title compound with an equimolar amount of bromine occurs as electrophilic addition at the double C19=C20 bond with formation of 14α-hydroxy- or 14α-methoxy-19R-bromo derivatives. The reaction with excess bromine (3 equiv) leads to the formation of 16S-bromo derivatives. The bromination process is accompanied by formation of epoxy bridge between the C14 and C20 atoms. X-Ray analysis revealed two polymorphic modifications of (16S,19R)-16,19-dibromo-14β,20-epoxydihydroquinopimaric acid methyl ester.

ChemInform Abstract: Reactions of 2H,5H-Imidazo(1,5-b)isoquinoline-1,3-diones with Bromine.

Treatment of 2H,5H-imidazo[1,5-b]isoquinoline-1,3-diones 1 with one molar proportion of bromine in glacial acetic acid gave complex mixtures. The major component of each mixture was the corresponding 1,3-dioxoimidazo[1,5-b]isoquinolinium bromide 4; other constituents shown to be present included the 1,3-dioxo-10-bromoimidazo[1,5-b]isoquinoliniumbromides 5,2H,5H-imidazo[1,5-b]isoquinoline-1,3-diones 3, isocarbostyryl derivatives 9, dihydroisocarbostyryl derivatives 10, and 3-carbamoylisoquinolines 8. Reaction of the 2H,5H-imidazo[1,5-b]isoquinoline-1,3-diones 1 in glacial acetic acid with excess of bromine afforded 1,3-dioxo-10-bromoimidazo[1,5-b]isoquinolinium bromides 5 as principal products. Bromination of compounds 1 in carbon tetrachloride yielded mainly 1,3-dioxo-2H-imidazo[1,5-b] isoquinolinium bromides 12.

C−H Bond Activation and Subsequent C(sp2)−C(sp3) Bond Formation: Coupling of Bromomethyl and Triphenylphosphine in an Iridium Complex

Treatment of HC≡CCH(OH)CH═CH2 with [IrHCl(CO)(PPh3)3]BF4 at room temperature afforded an iridacyclohexadiene, [Ir(CH═C(PPh3)CH═CHCH2)Cl(CO)(PPh3)2]BF4 (1). The reactivity of complex 1 had been investigated. Reaction of 1 with 1 equiv of bromine produced an iridacyclopentadiene, [Ir(CH═C(PPh3)CH═C(CH2Br))Cl(CO)(PPh3)2]BF4 (2). When excess bromine was used, iridacyclopentadiene 2 underwent subsequent intramolecular C(sp2)−C(sp3) coupling between the exocyclic −CH2Br group and a phenyl of the PPh3 ligand, leading to the formation of a fused iridacycle complex, [Ir(CH═C(PPh3)C(Br)═C(CHBr))(P(C6H4)Ph2)Cl(CO)PPh3]Br3 (3). A mechanism for the formation of complex 3 starting from 1 was proposed, in which the process involved a triple C−H activation as well as a rare C(sp2)−C(sp3) reductive elimination.

Titrimetric and spectrophotometric determination of doxycycline hyclate using bromate-bromide, methyl orange and indigo carmine

One titrimetric and two indirect spectrophotometric methods are described for the determination of doxycycline hyclate (DCH) in bulk drug and in its formulations. The methods use bromate-bromide, methyl orange and indigo carmine as reagents. In titrimetry (method A), DCH is treated with a known excess of bromate-bromide mixture in acid medium and the residual bromine is back titrated iodometrically after the reaction between DCH and in situ bromine is ensured to be complete. In spectrophotometric methods, the excess of bromine is estimated by treating with a fixed amount of either methyl orange (method B) or indigo carmine (method C) and measuring the change in absorbance either at 520 or 610 nm. Titrimetric method is applicable over 1-8 mg range and the calculations are based on a 1:2 (DCH:bromate) stoichiometric ratio. In spectrophotometry, the calibration graphs were found to be linear over 0.25-1.25 and 1-5 ?g mL-1 for method B and method C, respectively, with corresponding molar absorptivity values of 2.62 ?105 and 6.97 ? 104 L mol-1 cm-1. Accuracy and precision of the assays were determined by computing the intra-day and inter-day variations at three different levels of DCH.

Synthesis, characterization and bromination of bis(phosphinoferrocenyl) gold(I) compounds

Reaction of [(dppf)Au 2Br 2] ( 3) {dppf = 1,1′-bis(diphenylphosphino)ferrocene} and [(dippf)Au 2Br 2] ( 4) {dippf = 1,1′-bis(diisopropylphosphino)ferrocene} with excess bromine yields two new complexes [(C 5H 4Br 3)(PR 2)AuBr] (R = Ph, 5; R = i-Pr, 6). Bromination of the free diphosphinoferrocene ligands produces the expected brominated cyclopentenes (C 5H 4Br 3)(PR 2) (R = Ph, 7; R = i-Pr, 8) in good yields; however, these compounds could not be complexed to gold due to reduced basicity of 7 and 8. When the bromination is performed under wet aerobic conditions the oxidized pseudo-centrosymmetric product, [doppf][FeBr 4] ( 9) {doppf = 1,1′-bis(oxodiphenylphosphino)ferrocene, is formed as the major product. Solid-state structures of 1, 2, 4, 6, and 9 have been established by means of single-crystal X-ray crystallography.

Regioselective bromination of (Tetraphenyltetrabenzoporphyrinato)palladium(II). Synthesis of a new octabromo derivative of the tetraphenyltetrabenzoporphyrin series

Bromination of (meso-tetraphenyltetrabenzoporphyrinato)palladium(II) with bromine in the presence of tetramethylammonium bromide occurs exclusively at the benzene rings fused to the porphyrin system while the phenyl rings in the meso positions are not involved. The corresponding octabromo-substituted complex was obtained using a large excess of bromine on prolonged reaction time. The complex was isolated and characterized by 1H NMR spectra, electronic absorption spectra in the UV and visible regions, and MALDI-TOF mass spectra. It was assigned the structure of symmetric (22,23,72,73,122,123,172,173-octabromo-5,10,15,20-tetraphenyltetrabenzoporphyrinato)palladium(II).