The mass spectra of derivatives of uridine, adenosine, cytidine and guanosine are recorded. Derivatization techniques include permethylation, acetylation, trifiuoroacetylation, trimethylsilylation and the synthesis of 2',3'-O-isopropylidenes and 2',3'-0-phenylboronic esters. Sequential derivatization by a selective combination of some of these procedures results in nucleosides which are blocked with a characteristic group at the cis 1,2 diol position, and, which contain other substituent groups that enhance the volatility of the compound. The specific substitution at the cis-glycol region has been shown to be particularly useful in asymmetrically derivatizing dinucleoside phosphates since certain fragment ions from their mass spectra indicate the sequence of the two nucleoside components. Sequence isomers such as adenylyl-(3'-5')-uridine and uridylyl-(3'-5')-adenosine can be unambiguously distinguished.

No abstract

Work performed under the auspices of the U. S. Atomic Energy Commission.

Concerns have surfaced regarding the safety of several online demonstrations on the decomposition of H2O2. In the demonstrations, a H2O2 decomposition reaction happens rapidly followed by a plume of condensed water vapor shooting out of the flask. A modified protocol with improved safety considerations is described for the decomposition of H2O2 demonstration. In these demonstrations, 44 μm and 10 μm size particles of MnO2 are compared in catalyzing the decomposition of 30% H2O2 in a 1 L plastic bottle. The use of 44 μm particle size MnO2 slowed the reaction significantly relative to 10 μm particle size MnO2. The experimental procedure developed using 44 μm particle size MnO2 is reliable and has been tested dozens of times over the past ten years. Critical parameters were identified to ensure the success of the demonstration without compromising the safety of the demonstrator and the audience. This demonstration can easily be conducted in a large well-ventilated classroom and affords an excellent presentation for teaching students about rates of chemical reactions and several topics related to catalysis.

Single-crystal X-ray structures, melting points, and students’ specific rotation results on carvone semicarbazone derivatives are presented with experimental details. Critical parameters are identified to ensure the success of the experiment. Procedures developed here were tested in a laboratory course, consisting of approximately 70 students over three semesters. This experiment teaches undergraduate students important new instrumental methodology for characterizing a sample, allowing students to gain skills from hands-on experience using modern analytical instrumentation, and analyzing data to achieve a conclusion.