Deuterium labelling bromination

Photochlorination of 1,1-dichlorocyclopropane (1) yielded a mixture of 1,1,1,3-tetrachloro-propane (2) and 1,14,3,3-pentachloropropane (3), the latter by subsequent chlorination of the primary product tetrachloropropane. The ring opening by a chlorine radical occurred with inversion as demonstrated by the use of deuterium-labeled starting material. Photo-bromination of 1,1-dichlorocyclopropane gave l,3-dibromo-l,l-dichloropropane as the only product. ... 

Deuterium bromide is obtained from D20 and thionyl bromide15 in the same way (for preparation of liquid DBr from the elements see Kalinatchenko et al.16). Its addition to carbon-carbon multiple bonds has been used mainly for the preparation of various deuterium-labeled halogeno-ethanes and -ethyl-enes,4a 17,18 for not only is the DBr readily added but also the bromine can be removed selectively from the products e.g. ... 

Deuterated Cyclohexenes. 1,3,3-Trideuterocyclohexene (5) was synthesized from cyclohexanone according to the method of Fahey and Monahan (27) except that diazabicyclononane (DBN) was used instead of potassium t-butoxide in the final step. 3,3,6,6-Tetradeuterocyclohexene (6) was obtained from Merck, Sharp, and Dohme (>98%-d4). The degree of deuteration of the labeled cyclohexenes was determined by converting them to the corresponding 1,2-dibromocyclohexanes by treatment with bromine in carbon tetrachloride. The deuterium content of these dibromocyclohexanes was determined conveniently by observing the M-bromine region of the mass spectrometry. 

Figure 6-11 shows a cyclic case where one of the faces of a cyclopentane ring has been labeled by a deuterium atom. Deuterium has the same size and shape as hydrogen and it undergoes the same reactions. It distinguishes between the two faces of the ring the bromine atom is cis to the deuterium in the reactant, so the nucleophile is cis to the deuterium in the retention product. The nucleophile is trans to the deuterium in... 

The brominated sugars are usually quite stable and can be useful for a variety of purposes [151]. Substitution of bromine with deuterium can be used for preparation of labeled carbohydrates, while substitution with hydrogen sometimes can be used for inverting the stereochemistry. Noteworthy is the conversion of D-glucuronic acid derivative 61 into the corre-... 

The answer is found in a series of studies begun by Lars Melander (of the Nobel Institute of Chemistry, Stockholm) and extended by many other workers. A variety of aromatic compounds labeled w ith deuterium or tritium were subjected to nitration, bromination, and Friedel-Crafts alkylation. It was found that in these reactions deuterium or tritium is replaced at the same rate as protium there is no significant isotope effect. 

Impurities in recoil systems present much the same problem as in any other chemical system. Their presence is perhaps a bit more serious in recoil work, particularly in gas-phase studies. This can be illustrated by a siiecific example. In studying the effect of perdeuteration on product yield from the reaction of carbon-11 with ethane, it was found that the ethylene- C yield tended to be erratic. A standard method of preparation of ethaiie-dg involves the reduction of ethylene-d4 with deuterium. Traces of ethylene remaining are removed by treatment with bromine, a most effective method. The removal of bromine is accomplished by the usual techniques and is continued until its presence can no longer be detected. Under the circumstance in question it meant that the mole fraction of bromine in the mixture was less than 10 . In the same system, ethylene- C was produced at a concentration of about 10 mole fraction. The trace of bromine remaining was sufficient to scavenge part of the labeled ethylene. The problem was readily solved by using another method of purification. 

Even though IBA techniques provide a sensitive measure of the wetting and phase behavior of a particular system, some caution is required in their use, as the labeling (e.g., with deuteriirm or other elemental markers) itself can have a dramatic effect on the observed phase behavior. This is clearly illustrated by studies on partially brominated polystyrene, where bromine enables RBS characterization, but also renders brominated styrene immiscible with hydrogenous ( normal ) polystyrene. Even relatively subtle labeling with deuterium, though it may have little effect on behavior far away from the phase boimdary, can significantly alter the position of the phase boimdary. ... 

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