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Bromine transfer

Similar reactions occur with ammonia and HOBr (19—25), but since HOBr is a stronger electrophile than HOCl, formation rates are faster. Because of rapid bromine transfer between bromamines, equihbrium concentrations of the respective bromamines are obtained quickly. Mon ohrom amine predominates at basic pH at high N Br ratios. Below pH 8.5, NHBr2 and NBr predominate. Tribromamine formation is favored at lower pH and higher Br N ratios. The bromamines are less stable than chloramines but are better disinfectants. [Pg.453]

The authors (ref. 19) managed to perform this reaction selectively as telomerization at the C-Br bond of bromoform using initiating system Fe(CO)5 + DMF, which facilitates a bromine transfer at a step of a chain transfer (ref. 19). In this case only one row of telomers is formed which contain three bromine atoms in molecules ... [Pg.186]

The nature of mass transport in MEMED has been confirmed with both ampero-metric and potentiometric studies of bromine transfer from an aqueous phase to DCE [79]. Figure 17 shows typical amperometric data for this case, in which the DCE phase acts as a sink for Br2, and a depleted region of Br2 is measured adjacent to the droplet in the aqueous phase. Video images are also provided, which correspond to particular times during the amperometric transient at position (3) the edge of the developing concentration boundary layer, around the drop, reaches the electrode the concentration profile is then mapped out between points (3) and (4). The measured current, i, can be related to the local concentration, c, via... [Pg.351]

FIG. 17 (a) Typical current (/)-time (t) characteristics for bromine transfer from an aqueous phase... [Pg.352]

A similar cyclization as described above has been used for the carbocyclization of bromopropargyl ethers 41 in the pyrimidinedione series using tributyltin hydride [95SL705]. If the reaction is carried out using triethylamine, carbocyclization with bromine transfer takes place (41 -> 42). The authors suggest that this reaction proceeds through a radical pathway. [Pg.18]

Therefore, the crude TMS-enol ether 23 is used as substrate in a bromination reaction. In this reaction, enolate 24 acts as a nucleophile after in situ cleavage of the TMS ether and attacks the bromine transfer reagent. Several systems are known for this type of reaction molecular bromine, sodium bromide/lead(IV) acetate and N-bromosuccinimide. [Pg.245]

The reaction of mlz 109 with BrCF3 was almost as fast with >99% of the product channels giving the isotopic doublet at mJz 173 and 175 for the product of bromine transfer and dimethylation (equation 17) along with a trace of Br-. No reaction was observed between (CH30)2P0- and C1CF3 this finding indicates that the rate constant is less than our lower limit, >10-13 cm3 molecule-1 s-1. [Pg.65]

FIG. 17 (a) Typical current (/)-time (t) characteristics for bromine transfer from an aqueous phase to an expanding DCE drop measured at a 1 qm diameter Pt UME positioned beneath the growing drop. The images (l)-(4) correspond to the points indicated on the transient. The final drop size in (4) is 1.00 mm. Data are analyzed to produce (normalized) concentration vs. distance profiles, such as that in (b), showing experiment (O) and theory for a transport-limited process (—). [Pg.345]

Scheme 12. Bromine transfer radical addition reactions... Scheme 12. Bromine transfer radical addition reactions...
Transfer of a phenylseleno group can be accomplished simply by adding an excess (3 equiv) of diphenyl diselenide. Trichloroacetamide 7 was converted into bicyclic lactam 8 in 91% yield. On the other hand dimethylbromoacetamide 9 gave the corresponding Kharasch addition product 10 in 58% yield. The yield of 10 increased to 78% in the presence of 3 equiv of bromotrichloromethane, a bromine transfer reagent. [Pg.184]

The anomalous low Arrhenius parameters for the reactions between CF3 and CjHs Br or CgF Br [327] (see Table 26) have been attributed to pseudo bromine transfer according to... [Pg.76]

Bromination. This perbromide is useful for selective bromination of a ketone in the presence of a double bond (c/. pyrrolidone-2-hydrotribromide, 3, 240-241). In three cases reported yields are in the range 60-80%. Of course, this reagent can also be used for a-bromination of saturated ketones. No reaction was observed with camphor, however, or with esters. The intermediate monobromide formulated above in the preparation of (1) is formed on brominations with (1). In effect, the perbromide can be considered as a bromine-transfer agent. ... [Pg.97]

Murakami et al. were able to confirm this process by demonstrating bromine transfer from ethyl 3-bromoindole-2-carboxylate to form 4-bromo-7-methoxyindole-2-carboxylate. [Pg.58]

K. S. Chen, D. Y. H. Tang, L. K. Montgomery, and J. K. Kochi, J. Amer. Chem. Soc., 1974, 96,2201. This paper also contains information on the CFj-CHj-CH radical generated from CFs COj OBu or CF,I in the presence of C2Ht, or by bromine transfer from CF3-CH2 -CH8Br with triethyisilyl radicals. [Pg.42]

Zhang, J., Unwin, P R. Effect of fatty alcohol monolayers on the rate of bromine transfer across the air/ water interface Assessment of candidate models using scanning electrochemical microscopy. Langmuir 2002, 18, 1218. [Pg.449]


See other pages where Bromine transfer is mentioned: [Pg.319]    [Pg.186]    [Pg.36]    [Pg.118]    [Pg.656]    [Pg.242]    [Pg.206]    [Pg.580]    [Pg.130]    [Pg.165]    [Pg.300]    [Pg.10]    [Pg.212]    [Pg.10]    [Pg.431]    [Pg.9]    [Pg.105]    [Pg.82]    [Pg.436]    [Pg.58]    [Pg.78]    [Pg.5566]    [Pg.478]    [Pg.270]    [Pg.70]    [Pg.55]    [Pg.307]    [Pg.136]   
See also in sourсe #XX -- [ Pg.74 , Pg.77 , Pg.80 , Pg.81 ]




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Amino acids, bromination, solid-phase H-atom transfer

Bromine atom transfer

Bromine, free radical transfer reactions

Bromine-containing charge transfer

Bromine-olefin charge transfer complexes as essential intermediates in bromination

Radical bromine-transfer

Transfer bromination

Transfer bromination

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