L- bromine

The approximate composition of surface water in the Dead Sea in 1966 (49) was given as 35 g/L calcium chloride 130 g/L magnesium chloride nearly 80 g/L sodium chloride more than 10 g/L potassium chloride nearly 4 g/L bromide and about 1 g/L sulfate. At 400 m depth the bromide concentration was 6 g/L. Bromine in Israel is produced from the Hquors left from potash production and the bromide content of these Hquors is 14 g/L. 

Strong electron-donating groups enhance electrophilic substitution and direct ortho/para. Thus, dimethylaminobenzofuroxans can be nitrosated and diazo-coupled (69AHC(lO)l) bromination of 4-, 5-, 6- and 7-aminobenzothiazoles occurs ortho and para to the amino group. 

Flo. 1.—Representative compounds which, on photobromination, afford isolable products with bromine atoms in place of the identified hydrogen atoms, [(a) R1 H.OMe.OAc R2 = Me,Ac p anomers much more reactive same products are formed from C-5 epimers (b) R — Ac,Bz p anomers much more reactive same products are formed from C-5 epimers (c) mixed C-S epimeric bromides are formed (d) mixed 04 epimeric bromides are formed (e) R — Ac,Bz configurations at C-2—C4 may vary (f) X OJVOBz (g) react at 01 and 05 the a anomers react much less readily and give no products of C-l bromination (h) R1 — H,N02 R2 - Ac,Bz],... 

Figure 2 shows the bromo derivatives (6). In the tetraaxial benzoate, a C-l-ring oxygen distance of 1. 37 I is observed, which corresponds to a considerable shortening of almost the same magnitude as in the fluoro and chloro derivatives. The C-l—bromine bond is concurrently- stretched to 2.003... 

Without purification, sulfoxides 67 were heated in toluene in the presence of NaHC03 to give elimination product 68 along with a saturated ketone 69 in 76% and 17% isolated yields, respectively. On the other hand, the same transformation using PhSeNa, instead of PhSNa, provided 68 as the sole product in 72% from 65. Finally, treatment of 68 with LiAlH4 reduced the ethylcarbamate function and removed the C-l bromine atom to afford codeine. 

Leaching of gold bearing material achieved 89-93% gold extraction using an acidic (pH 2 with sulphuric acid) lixiviant with the composition of 47-48 g/L bromine and 10 g/L bromide. The leach test results are presented in Table 11. The ICP scan data for major elements are shown in Table 12. 

Uyeo and his colleagues (30) treated dihydrotaxinol tetraacetate (XLIX) with acetic anhydride and perchloric acid and obtained the enol acetate (L), bromination of which gave the 14-bromo compound (LII). Dehydrobromination gave the a, -unsaturated ketone (LI), which, notably, has 271 mp., 3500, and possesses only one olefinic... 

Figure A3.10.9 STM images of Si(l 11) surfaces before (a) and after (b) etching by bromine at 675 K. In (a) the (7 X 7) reconstmcted surface is seen. In (b), the rest layer consisting of triangular arrays of Si atoms has been exposed by etehing [28], Both images show a 17 x 17 mn area.

Tanaka S, Yau S-L and itaya K 1995 In situ scanning tunneiing microscopy of bromine adiayers on Pt(111) J. Electroanal. Chem. 396 125-30... 

Owing to the corrosive action of bromine upon corks j-jg 7, l. and rubber stoppers, ground glass joints are recommended in this preparation. The apparatus, depicted in Fig. Ill, 37, 1, is particularly convenient for the preparation of bromides from alcohols. A double surface condenser is fitted into D and a round-bottomed flask is fitted on to the ground glass joint at C R is a three-way stopcock f which permits the removal of the contents of A without disconnecting the apparatus. For preparations of moderate size, A has a capacity of 60 or 100 ml. and a 250 or 500 ml. flask is attached at C. 

A classical reaction leading to 1,4-difunctional compounds is the nucleophilic substitution of the bromine of cf-bromo carbonyl compounds (a -synthons) with enolate type anions (d -synthons). Regio- and stereoselectivities, which can be achieved by an appropiate choice of the enol component, are similar to those described in the previous section. Just one example of a highly functionalized product (W.L. Meyer, 1963) is given. 

Synthesis of (A) started with the combination of 2,4,6-trimethylphenol and allyl bromide to give the or/Ao-allyl dienone. Acid-catalyzed rearrangement and oxidative bydroboration yielded the dienone with a propanol group in porlactone ring were irons in the product as expected (see p. 275). Treatment with aqueous potassium hydroxide gave the epoxy acid, which formed a crystalline salt with (R)-l-(or-naphthyl)ethylamine. This was recrystallized to constant rotation. 

One type of o-aminobenzyl anion synthon is a mixed Cu/Zn reagent which can be prepared from o-toluidines by / i.s-trimethylsilylation on nitrogen, benzylic bromination and reaction with Zn and CuCN[l]. Reaction of these reagents with acyl halides gives 2-substituted indoles. 

Addition of halogens proceeds stepwise, sometimes accompanied by oxidation. Iodine forms 2,3-diiodo-2-butene-l,4-diol (53). Depending on conditions, bromine gives 2,3-dibromo-2-butene-l,4-diol, 2,2,3,3-tetrabromobutane-l,4-diol, mucobromic acid, or... 

Health and Safety Factors. Fluorocarbons containing bromine or iodine are more toxic than the corresponding chloro compounds. When the ratio of the fluorine to other halogens is high, the toxicity can be quite low, especially for bromofluorocarbons. Perfluoro-l-bromooctane [423-55-2] has an LD q of greater than 64 mL/kg when adininistered into the gastrointestinal tract, and has Htde effect when instilled into the lungs (49). Other examples are included in Table 7. 

Selective monohalo alkylations were achieved when chlorobromoalkanes such as l-chloro-S-bromo-S-methjIbutane were used as halo alkylating agents (47). The bromine is replaced preferentially ... 

An alternative synthesis of (Z)-l-halo-l-alkenes involves hydroboration of 1-halo-l-alkynes, followed by protonolysis (246,247). Disubstituted ( )-and (Z)-a1keny1 bromides can be prepared from ( )- and (Z)-a1keny1 boronic esters, respectively, by treatment with bromine followed by base (248). 

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