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mequiv of Rh) of pdichlorotetraethylenedirhodium(1) and 288 mg (0.412 mequiv) of polymer 7 was placed in a Schlenk tube and the vessel was freed from oxygen by alternately evacuating and charging with dry and deoxygenated nitrogen. Benzene (4 mL) was added, the mixture was stirred for 10 min, and 8 mL of ethanol was added. The mixture was stirred at ambient temperature for 24 h under a stream of nitrogen to afford a light brown polymer-attached Rh catalyst 8.Following the addition of 665 mg (5.15 mmol) of a-acetamidoacrylic acid under nitrogen, the reaction mixture was charged with hydrogen by alternately evacuating and then filling with hydrogen. The uptake of hydrogen was measured with a graduated cylinder connected to the reaction vessel, and the hydrogenation was run under 1 atm at 25 OC. The uptake of hydrogen ceased in 2 h. The polymer catalyst was filtered, the solvents were evaporated from the filtrate, and the residue was dried under reduced pressure. Conversion was measured by IH N M R and optical yield was determined by use of a polarimeter with reference to the value for the authentic sample, conversion loo%, optical yield 75.0%.In the recyclization reaction, polymer filtration and all other procedures for the reaction were performed under nitrogen or hydrogen, and exposure to oxygen was strictly precluded. Abstract: A time-dependent change in the ultraviolet absorbance at 290 nm of the indole ring of tryptophan has been observed, using a stopped-flow spectrophotometer, when tryptophan was rapidly transferred from water into deuterium oxide-water solution. From this experiment, the rate constant of the hydrogen-deuterium exchange reaction of the tryptophan N H group has been determined at various pH values and at several temperatures. Stopped-flow ultraviolet spectroscopy has also been used for an examination of hydrogen exchange kinetics of the tryptophan residues of hen egg-white lysozyme. Three of the six tryptophan residues of this protein molecule were deuterated in 50 min at pH 5.5 and 22 "C. These three residues are probably Trp-62, Trp-63, and Trp-123. When N-acetylglucosamine was present the deuteration rates were markedly lower.

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