Tritium aqueous

Only within the past few years have serious attempts been made to estimate quantitatively the differences in reactivity between thiophene and benzene and between the 2- and 3-position of thiophene. Careful investigation on the acid-induced exchange of deuterium and tritium have shown that the ratios of the exchange rates in the 2- and 3-positions are 1045 61 for deuterium and 911 60 for tritium in 57% by weight aqueous sulfuric acid at 24.6°C. A kinetic isotope effect in the isotopic exchange has been found to be k-r/kr, = 0.51 0.03 in the 2-position and kr/kjy — 0.59 0.04 in the... 

To measure the volume of the blood in an animal s circulatory system, the following experiment was performed. A 5.0-mL sample of an aqueous solution containing 1.7 X 105 counts per minute (cpm) of tritium was injected into the bloodstream. After an adequate period of time to allow for the complete circulation of the tritium, a 5.0-mL sample of blood was withdrawn and found to have 1.3 X 103 cpm on the scintillation counter. Assuming that only a negligible amount of tritium has decayed during the experiment, what is the volume of the animals circulatory system ... 

Electronically excited states of organic molecules, acid-base properties of, 12,131 Energetic tritium and carbon atoms, reactions of, with organic compounds, 2, 201 Enolisation of simple carbonyl compounds and related reactions, 18,1 Entropies of activation and mechanisms of reactions in solution, 1,1 Enzymatic catalysis, physical organic model systems and the problem of, 11, 1 Enzyme action, catalysis of micelles, membranes and other aqueous aggregates as models of, 17. 435... 

A scintillation counter is used to measure tritium /3 particles adjacent to the surfaces of tritiated sodium dodecyl sulfate in 0.115 M aqueous NaCl solution and tritiated dodeca-nol in dodecanol. The former system is surface active and the latter is not, so the difference between the measured radioactivity above the two indicates the surface excess of sodium dodecyl sulfate. The number of counts per minute arising from the surface excess As is related to the surface excess in moles per square centimeter r by the relationship As = 4.7 x 1012 T1. Use the following data (25°C) to construct the adsorption isotherm for sodium dodecyl sulfate on 0.115 M NaCl ... 

A mixture of 1 gram benzene insoluble residue from the extraction of Ireland Mine coal ana 10 ml. 10% aqueous sodium hydroxide solution was sealed in a glass vial and heated at 100°C. for 4 days in a thermostat. After cooling to room temperature the vial was opened, the aqueous solution decanted, distilled over, and analyzed for tritium content. The solid residue was filtered, washed thoroughly with distilled water, dried, and analyzed for tritium. 

D-Glutamic acid was not found in irradiated solutions of free L-glutamic acid, which agrees with the results of Sharpless et al. 83), who found no D-alanine in irradiated L-alanine. However, Evans 14) found that a major loss of L-leucine-4,5-T, methionine-T(G), and phenylalanine-4-T amino acids stored in aqueous solution occurs as a result of racemization. In these cases, it seems likely that the inversion is a result of indirect action brought about by 0-radiation from tritium decay. 

Potatoes. Treatment. Seed pieces of White Rose, Russet Burbank, and Pontiac potatoes were treated with an aqueous solution of 25 p.p.m. of tritium-labeled gibberellie acid (specific activity 108 /xc. per mg.) for 5 minutes. The dried pieces were kept overnight at 68° F. (80 to 85% relative humidity) and then planted at the University Farm, Davis, Calif. Thirty days later, leaves and rhizomes of the White Rose variety were sampled to determine the translocation of gibberellie acid. New potatoes were harvested 60 days after planting. The... 

Rate constants for deuterium or tritium exchange of benzene, naphthalene, and other aromatic molecules have been measured in concentrated solutions of sulfuric or perchloric acid. Conveniently, Cox has extrapolated values to aqueous solution from plots of log/cx against Xa and corrected them for isotope effects (e.g., k /kp) to yield kA.72... 

However, under somewhat different conditions (aqueous acetonitrile at 85°), no evidence for the free carbonium ion could be found (Bethell et al., 1965). Moreover, the invariance of the product proportions when water is replaced by deuterium oxide, coupled with the observation of a large tritium isotope effect on the formation of diphenylmethanol, is consistent only with the ylid mechanism (equation 21) (Bethell et al., 1969). For reaction of diarylmethylenes with alcohols, substantial hydrogen-isotope effects are observed, consistent with both equations 21 and 22. 

With the development of liquid scintillation counters which permit tracer levels of tritium to be measured accurately, isotope exchange reactions are now usually carried out with tritium rather than deuterium. Frequently, however, it is useful to compare rates of exchange for all three isotopes and deuterium exchange may be followed using, for example, mass spectrometry [22]. An example of the application of isotope exchange to proton transfer from carbon is shown in eqns. (8) and (9) for the hydroxide ion catalysed exchange of phenylacetylene in aqueous solution [23], viz. 

The trap solution from the lower temperature is defined as containing the aqueous tritium from the sample and that from the higher temperature the organically bound tritium (OBT). 

Despite the variability, some broad trends can be discerned. In the lysimeters, the decrease in the concentration of tritium over the growing season was approximately 50% for both the loam and the sand but only just over 30% for the peat. The loss of tritium in the small containers followed a similar pattern. The apparent differences in the values given in Table 2 may be because of the large variability in individual results. For all of the soil types, tritium in the surface layer was predominantly present as OBT, the values for aqueous tritium at the end of the season being at or close to the detection limit. 

The size of the lysimeters was sufficient for soil cores to be taken just before the harvesting of crops. Concentrations of tritiated water and OBT were determined at different depths in the soil. The results summarised in Table 3, showed that the organically bound tritium remained largely in the upper layer which represents the depth of tillage. The concentration of aqueous tritium was low and often below detection limits. However, where measurable values were obtained, concentrations were relatively uniform with depth. 

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