Bromine cyanides

Cyanogen bromide (Bromine cyanide) CNBr Extremely irritating and toxic vapours Contact with acids, acid fumes, water or steam can produce toxic and corrosive fumes Transparent crystals with a penetrating odour Melting point 52°C Boiling point 61 °C Vapour density 3.6 Water soluble... 

Although the biosynthetic cascade hypothesis predicts the co-occurrence of endiandric acids D (4) and A (1) in nature, the former compound was not isolated until after its total synthesis was completed in the laboratory (see Scheme 6). Our journey to endiandric acid D (4) commences with the desilylation of key intermediate 22 to give alcohol 31 in 95% yield. The endo side chain is then converted to a methyl ester by hydrolysis of the nitrile to the corresponding acid with basic hydrogen peroxide, followed by esterification with diazomethane to afford intermediate 32 in 92% overall yield. The exo side chain is then constructed by sequential bromination, cyanide displacement, ester hydrolysis (33), reduction, and olefination (4) in a straight-... 

A liquid-phase double-replacement reaction between bromine cyanide (A) and methyl-amine takes place in a PFR at 10°C and 101 kPa. The reaction is first-order with respect to each reactant, with kA = 2.22 L mol 1 s 1. If the residence or space time is 4 s, and the inlet concentration of each reactant is 0.10 mol L-1, determine the concentration of bromine cyanide at the outlet of the reactor. 

Several methods are available for the synthesis of CFsSBr. Either CF2BrSBr is fluorinated at 100°C with antimony trifluoride (186) or CFsSCl is reacted with bromine cyanide over activated carbon at 70°C (86). Apart from that it is obtained always contaminated with CFsSSCFj in the reaction between Hg(SCF8)2 and bromine (31) these compounds react at 0°C to give a mixture composed of 56% CFsSBr and 45% CFjSSCFs. 

Synonyms bromine cyanide bromocyan bromocyanogen cyanobromide Uses... 

Structure 190 has been converted into key intermediates 191a and 191b via bromination, cyanide displacement, and benzylation (Scheme 18). Cyclization of 191 occurs upon reduction of the nitro group to give 192 <2004BMC3187>. The A, iV -dibenzyl derivative of 190 leads to similar products <2004JME3187>. 

Pentamethinestreptocymine Dyes are formed by reaction of bromine cyanide, chlorine cyanide, or 2,4-dinitrochlorobenzene with pyridine and cleavage of the resultant compounds with primary or secondary amines. The tetraacetal of gluta-conaldehyde is also used to form the methine chain [2], The dyes can be used to dye paper. 

Carbon-bromine bond distances in some bromoacetylenes are listed in Table 39. The bond lengths are nearly constant at about 179 pm and possible variations due to different substituents at the opposite carbon atom are smaller than the experimental uncertainties and systematic differences between the different types of bond lengths. The rs value for the C—Br bond distance in the cyano compound [178.9(2) pm] is equal to the value derived for acetylene [179.16(30) pm]. Shortening of the bond by ca 4 pm occurs in the electronic ground state of the bromine cyanide cation. 

Syntheses from Acid Hydrazides with Bromine Cyanide... 

Acid hydrazides are cyclized by bromine cyanide in aqueous bicarbonate or other solvents to form 5-substituted 2-amino-l,3,4-oxadiazoles [Eq. (6)].48, 78,93, 94 The yields here are almost without... 

Arylamino-5-amino-l,3,4-oxadiazoles are formed from 4-aryl-semicarbazides with bromine cyanide [Eq. (7)],98 but l,4-diphenyl-3-... 

The ImtiEd volume of fluid in a vat is t be 5 dm with a bromine cyanide coBcen--tration of 0.05 mol/dm. The specific reaction rate constant is... 

What if ytm assumed that the reaction in Example 4-11 was first-order in methyl amine (B> and zero-order in bromine cyanide. Since it is in excess at the start of the reaction, show that the concentration of methyl amine at any time f is... 

The concentrations of bromine cyanide (A), and methyl atnme are shown as a ftmc-tioft of time in Figure E4-11.1, and the rate is shown in Figure B4-11,2. For first- and Zero-order reactions we can obtain analydcal solutions for semibatch reactom operated isodietmally. 

What safety precautions should you take with the ethylene oxide format tion discussed in Example 4-6 With the bromine cyanide discussed in Example 4-11 ... 

Solve for the concentrations of bromine cyanide and methyl bromide and the rate of reaction as a function of time. 

What should you do if some of the ethylene glycol spla.shed out of reactor onto your face and clothing itiinr. Recall ivnH. stVi.nrg/.) What safety precautions should you take with the ethylene oxide forn tion discussed in Example 4-6 With the bromine cyanide discussed E.xampie 4-9 ... 

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