Bromal

In a 2-1. three-necked, round-bottomed flask fitted with a liquid-sealed mechanical stirrer, a dropping funnel, and an efficient reflux condenser are placed 720 g. (226 cc., 4.5 moles) of bromine (Note i) and 1.5 g. of sulfur (Note 2). A glass tube is connected to the top of the condenser to carry the evolved hydrogen bromide to a gas trap (Org. Syn. 14, 2). Sixty-nine grams (69 cc., 0.52 mole) of dry paraldehyde (Note r) is added slowly, with stirring, over a period of about four hours. The reaction proceeds under its own heat during the addition of the paraldehyde subsequently the mixture is heated externally for two hours at 60-80°. The solution is distilled and a fraction collected over the range 155-175° (Note 3). 

On redistillation under reduced pressure there is obtained 220-240 g. (52-57 per cent yield) of reddish-yellow bromal, boiling at 59-62°/q mm., or 7i-74°/i8 mm. 

The use of sulfur as a catalyst increases the yield 5-10 per cent and causes no trouble in the purification. 

The fore-run amounts to 90-180 g. and consists mostly of bromine, bromoacetaldehyde, and dibromoacetaldehyde. An additional quantity of bromal may be obtained by treating this 

Broirjal has been prepared by brominating a solution of paraldehyde in ethyl acetate, and by passing bromine vapor through absolute alcohol.  

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Tribromoacetic acid [75-96-7] (Br CCOOH), mol wt 296.74, C2HBr302, mp 135°C bp 245°C (decomposition), is soluble in water, ethyl alcohol, and diethyl ether. This acid is relatively unstable to hydrolytic conditions and can be decomposed to bromoform in boiling water. Tribromoacetic acid can be prepared by the oxidation of bromal [115-17-3] or perbromoethene [79-28-7] with fuming nitric acid and by treating an aqueous solution of malonic acid with bromine. 

In the oxidation of tns(2,2,3,3 tetrafluoropropyl) phosphite by oxygen, bromal exhibits a strong catalytic effect, whereas chloral is less effechve [101] (equation 93)... 

The isobomeol so formed melts at 212°, but the determination must be carried out in a sealed tube, as the melting-point is very dose to the temperature of sublimation. It is, however, very rarely that the isobomeol so prepared is free from impurities, and the melting-point will often be found to be as low as 203° to 205°. It is therefore necessary to pare derivatives of the isobomeol in order to identify it with certainty. Kie compound with bromal melts at 71° to 72°. Other compounds will be found mentioned under isobomeol . By dehydration by means of zinc chloride, isobomeol is easily converted into camphene, melting at about 49° to 50°. 

Borneol forms crystalline compounds with chloral and bromal, the. former melting at 55° and the latter at 104° to 105°. 

Halogen-alkanale werden durch Hefe selektiv zu Halogen-alkanolen reduziert. Ein klassisches Verfahren ist die Reduktion von 2,2,2-Tribrom-acetaldehyd (Bromal) zu... 

Several examples of the binding of enzymes to poly(vinyl alcohol) are in the literature. These could possibly be used to treat enzyme deficiency diseases. In a recent example, trypsin was immobilized on poly(vinyl alcohol) fibers using maleic dialdehyde or bromal. While the reaction was more complete with bromal, the reaction with maleic dialdehyde gave a better support which showed decreasing activity with increasing enzyme content. The activity of the bromal activated system was independant of the enzyme content (52 ). Trypsin and papain were attached to poly(vinyl alcohol) by the reaction sequence shown in Equation 13. In this case, the crosslinked poly(vinyl alcohol) is treated by the 1,3-dioxalone derivative and then converted to either the isothiocyanate or the diazonium salt for coupling with the enzyme. The bound enzymes showed significant, altho reduced, activity in each case (53). 

Carl Lowig, 1803-1890. Professor of chemistry at Heidelberg, Zurich, and Breslau. He prepared bromine in 1825, but before his investigation was completed Balard had announced the discovery. Lowig discovered bromine hydrate, bromal hydrate, and bromoform, and was the founder of the Silesian chemical industry and of the Goldschmieden alumina works at Deutsch-Lissa. 

In the flash photolysis of chloral and bromal,39 the absorption spectra of CC1 and CBr only were observed and similar results were obtained in the flash photolysis of chloro- and bromo-picrins. 

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