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Substitution bromine

Halogen-substituted succinimides are a class of products with important appHcations. /V-Bromosuccinimide [128-08-5] mp 176—177°C, is the most important product ia this group, and is prepared by addition of bromine to a cold aqueous solution of succinimide (110,111) or by reaction of succinimide with NaBr02 iu the presence of HBr (112). It is used as a bromination and oxidation agent ia the synthesis of cortisone and other hormones. By its use it is possible to obtain selective bromine substitution at methylene groups adjacent to double bonds without addition reactions to the double bond (113). [Pg.536]

Alkylbenzenes such as toluene (methylbenzene) react with NBS to give products in which bromine substitution has occurred at the position next to the aromatic ring (the benzyiic position). Explain, based on the bond dissociation energies in Table 5.3 on page 156. [Pg.356]

With bromine monochloride at 0°C in a variety of solvents, 1 was converted into addition products, the product distribution being a function of solvent. A change in halogenating agent also altered the product ratio. (Scheme 4) Nucleophilic displacement reactions between these products and silver fluoride was found to cause preferential bromine substitution (83G149). [Pg.248]

Whereas the three possible selectivities, stereo-, regio- and chemo-selectivity, of bromine addition are determined in steps posterior to the formation of the ionic intermediate. Bromine addition is, therefore, more complex than bromine substitution, as regards the variety of the selectivities and as regards the mechanistic aspects which determine the product formation. [Pg.100]

Application of the bromine substitution reaction allows the synthesis of aminoamides, alkoxyamides of simple alcohols and sugars, depsipeptides and (NH) pseudopeptides, C2 symmetric compounds. [Pg.160]

If a target aminodicarboxyl units bears an aryl group in one of its side chains, retrosynthetic analysis indicates that a bromoamide synthon 12, bearing an aliphatic side-chain, should react with a nucleophilic partner carrying the aromatic side chain. In the alternative bromoamide 21, HBr elimination to cinnamic derivatives competes with the desired bromine substitution. [Pg.168]

The oxidation of a number of chloroalkanes and chloroalkenes including dichlorometh-ane, chloroform, 1,1,2-trichloroethane, and 1,2,2-trichloroethene (Vannelli et al. 1990). Although the rate of cometabolism of trihalomethanes increased with levels of bromine substitution so also did toxicity. Both factors must therefore be evaluated in the possible application of this strain (Wahman et al. 2005). [Pg.71]

They react with a solution of bromine in carbon tetrachloride by substitution and an equivalent quantity of hydrogen bromide is evolved (compare addition with unsaturated compounds). When the test is conducted with bromine water and a dilute aqueous solution of a phmiol, the sim of reaction is the separation of a sparingly soluble bromine substitution product. ... [Pg.1071]

We first selected the bromine-substituted TTF-type donor EDT-TTFBr2 (4,5-dibromo-TTS -ethylenedithiotetrathiafulvalene) [68] to achieve strong n-d interaction [69]. This donor molecule has two bromine atoms that cause attractive interaction with a halogen atom of MX4 anions. In this donor molecule the... [Pg.87]

Among the most important indirect methods of analysis which employ redox reactions are the bromination procedures for the determination of aromatic amines, phenols, and other compounds which undergo stoichiometric bromine substitution or addition. Bromine may be liberated quantitatively by the acidification of a bromate-bromide solution mixed with the sample. The excess, unreacted bromine can then be determined by reaction with iodide ions to liberate iodine, followed by titration of the iodine with sodium thiosulphate. An interesting extension of the bromination method employs 8-hydroxyquinoline (oxine) to effect a separation of a metal by solvent extraction or precipitation. The metal-oxine complex can then be determined by bromine substitution. [Pg.205]

Hartwig has reported an intramolecular/intermolecular process affording the 3-aryloxindoles 105 (Scheme 32).115 The intermolecular arylation of acetanilide derivative 104 is slower than the intramolecular arylation to form the oxindole. Thus, the overall transformation starts with cyclization followed by intermolecular arylation of indole. In order to slow down the intermolecular process and speed up the intramolecular reaction, chloroarene and bromine-substituted acetanilide precursors are used according to their respective reactivity with palladium(O) in the oxidative addition process. [Pg.314]

In oxidation-reduction methods bromine is employed as an oxidizing agent in place of iodine, because it is reduced quantitatively be the readily oxidized pharmaceutical organic substances in a reaction which results in either water-insoluble bromine substitution products, for instance ... [Pg.213]

In oxidation-reduction assays the use of bromine is judiciously carried out as an oxidizing agent effectively for such specific compounds which ultimately results into the formation of both bromine substitution and bromine additive compounds. These products of reaction are produced quantitatively and are mostly water-insoluble in characteristics and more interestingly they take place in an acidic medium. [Pg.214]

The D. pulchra furanone compounds generally consist of a furan ring structure with a substituted alkyl chain at the C-3 position and a bromine substitution at the C-4 position (Fig. 5). The substituent at the C-5 position may vary in terms of side chain structure. The natural furanones are halogenated at various positions by bromine, iodine, or chlorine [128]. D. pulchra produces at least 30 different halogenated furanones which are stored in specialized vesicles and are released at the surface of the thallus at concentrations ranging from 1 to 100 ng/cm2 [132]. Field experiments have demonstrated that the surface concentration of furanones is inversely correlated with the degree of colonization by marine bacteria [133]. [Pg.320]

In contrast, penta- and higher bromobiphenyls accumulated in the fish to a lesser extent than similar chlorobiphenyls. The accumulation decreased with increasing bromine substitution and a hexabromobiphenyl was the last bromobiphenyl still accumulated from water (2). [Pg.177]

Howard CJ, Evenson KM. 1976. Rate constants for the reactions of OH with CH4and fluorine, chlorine, and bromine substituted methanes at 296K. J Chem Phys 64 197-202. [Pg.99]

Cross-coupling reaction of alkenyl iodides with Ar3Bi were efficient under Pd catalysis [59] (Schemes 41 —4-3). Various alkenyl iodides furnished cross-coupling products in good yields in short reaction times under mild conditions. A bromine substituent did not affect the reaction and afforded the corresponding bromine-substituted products. [Pg.218]

A = Br3, BrCl2, IC12) [Sket and Zupan, 1984], An ethylene-A-bromomaleimide copolymer has been used for bromine substitution at allylic and benzyl positions [Yaroslavsky et al., 1970],... [Pg.767]

Bromine substitution, thymine/thymidine bromohydiins, 927-8 P-Bromohydroperoxides, nucleophilic substitution cycUzation, 233-4 2-(5-Bromo-2-pyiidylazo)-5-diethylamino-... [Pg.1447]

Laureacetal-B (70) is a tricyclic oxetane recently isolated from a marine alga. It has the interesting features of bromine substitution and a cyclic acetal structure. In view of the extreme ease of hydrolysis of 2-methoxyoxetane, it seems surprising that a strained ring cyclic acetal would be isolated from a marine source. Its structure assignment is based on spectral studies and chemical transformations (79CL301). [Pg.400]

Electron Transfer in Bromine-Substituted DNA Effect of the Disruption of Base Stacking... [Pg.124]

Marsh et al. [36] examined analogous p-hydroxybromodiphenyl ethers and their binding to TR. The diphenyl ethers (brominated or not) bind much less avidly than T3 or T4, probably owing to the absence of the 4-carboxyl group. 4-Hydroxydiphenyl ether had the lowest affinity for THR. Within the brominated diphenyl ethers, the lowest binding was observed with the unsubstituted 4-hydroxydiphenyl ether, followed by bromine substitution in the 3 - and 5-positions, and followed by substitution by iodine. [Pg.519]

PBBs with six or fewer bromine substitutions bioconcentrate in aquatic organisms such as fish, but the octabromo- and decabromobiphenyls do not bioconcentrate significantly in fish (Gobas et al. 1989 ... [Pg.318]

Polybrominated Biphenyls. PBBs do not readily translocate from soil to plants via root uptake (Jacobs et al. 1976, 1978). Therefore, PBBs may not bioconcentrate in plants. However, plant uptake data are limited, audit will be helpful to develop additional plant uptake data. Brominated biphenyls with bromine substitution 6 or less will bioconcentrate in aquatic organisms (Gobas et al. 1989 Norris et al. 1973 Opperhuizen et al. 1985 Zitko 1979 Zitko and Hutzinger 1976). PBBs are preferentially stored in the adipose tissue of animals (Kimbrough 1987). Although PBBs have been detected in fish-eating birds... [Pg.380]

When a double bond has two different allylic positions, e.g., CHiCH=CHCHiCH , a secondary position is substituted more readily than a primary. The relative reactivity of tertiary hydrogen is not clear, though many substitutions at allylic tertiary positions have been performed.11B It is possible to brominate both sides of the double bond.119 Because of the electron-withdrawing nature of bromine, the second bromine substitutes on the other side of the double bond rather than a to the first bromine. [Pg.695]


See other pages where Substitution bromine is mentioned: [Pg.1071]    [Pg.573]    [Pg.165]    [Pg.168]    [Pg.912]    [Pg.360]    [Pg.364]    [Pg.97]    [Pg.57]    [Pg.42]    [Pg.209]    [Pg.333]    [Pg.86]    [Pg.306]    [Pg.104]    [Pg.79]    [Pg.199]    [Pg.221]    [Pg.227]    [Pg.229]    [Pg.234]    [Pg.243]    [Pg.330]    [Pg.379]   
See also in sourсe #XX -- [ Pg.251 ]

See also in sourсe #XX -- [ Pg.157 ]




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3- Substituted imidazole 1-oxide bromination

Aromatic substitution reactions bromination

Benzene, acylation bromine substitution

Bromination electrophilic aromatic substitution

Bromination of substituted benzenes

Bromination substitution versus addition

Bromine (continued substitution

Bromine electrophilic aromatic substitution

Electrophilic Aromatic Substitution Reactions Bromination

Electrophilic aromatic substitution reactions brominations

Malonic acid, substituted bromination

Replacement (s. a. Substitution bromine

Selective radical bromination allylic substitution of H by Br

Substitution bromination

Substitution bromination

Substitution reactions, radical-mediated brominations

Substitution reactions, with bromine

Substitution, electrophilic bromination

Substitution, radical allylic bromination

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