Compound labels

Radiochemical tracers, compounds labeled with radioisotopes (qv), have become one of the most powerful tools for detection and analysis in research, and to a limited extent in clinical diagnosis (see Medical IMAGING TECHNOLOGY). A molecule or chemical is labeled using a radioisotope either by substituting a radioactive atom for a corresponding stable atom in the compound, such as substituting for H, for or for P, and for for... 

Eor products having relatively low specific activity, such as some compounds labeled with and which are synthesized on the scale of several millimoles, classical organic chemical separation methods may be utilized, including extraction, precipitation, and crystallization. Eor separation of complex mixtures and for products having high specific activity, such as those labeled with tritium, etc, chromatographic methods utilizing paper, thin... 

Compounds labeled H, or are extremely important ia understanding the absorption, distribution, metaboHsm, and excretion of these... 

X 16.101 cis-Platin is an anticancer drug with a structure jQ that can be viewed on the Web site, (a) What is the formula and systematic name for the compound cis-jf Platin (b) Draw any isomers that are possible for this compound. Label any isomers that are optically active, (c) What is the coordination geometry of the platinum atom ... 

The routine monitoring of every hazardous constituent of the effluent gases of operating incinerators is not now possible. EPA has established procedures to characterize incinerator performance in terms of the destruction of selected components of the anticipated waste stream. These compounds, labeled principal organic hazardous components (POHCs), are currently ranked on the basis of their difficulty of incineration and their concentration in the anticipated waste stream. The destraction efficiency is expressed in terms of elimination of the test species, with greater than 99.99 percent removal typically judged acceptable provided that toxic by-products are not generated in the process. 

For human studies, the choice of stable isotopes is limited because radioisotopes are associated with ionization radiation and thus with some potential harmful effects for humans. Studying the bioavailability of compounds labeled with stable isotopes requires complex techniques such as gas chromatography coupled with mass spectrometry (GC-MS), liquid chromatography coupled with MS (LC-MS), and atmo-... 

In order to obtain a compound labeled with a radioactive isotope for studies about the pancreas, p-2- and /i-3-sclenienyl alanine were prepared. Initially the synthetic route shown in Scheme 14, which allowed insertion of radioactive selenium as late in the synthesis as possible, was designed for the ji-2 isomer (116).149... 

Ealy [ 75 ] also used conversion to alkyl mercury iodides for the gas chromatographic determination of organomercury compounds in benzene extracts of water. The iodides were then determined by gas chromatograph of the benzene extract on a glass column packed with 5% of cyclohexane-succinate on Anakron ABS (70-80 mesh) and operated at 200 °C with nitrogen (56 ml min-1) as carrier gas and electron capture detection. Good separation of chromatographic peaks was obtained for the mercury compounds as either chlorides, bromides, or iodides. The extraction recoveries were monitored by the use of alkylmer-cury compounds labelled with 203 Hg. 

Synthesis of simple seven-membered ring compounds labelled with tritium... 

Testa and Dooley34 have also prepared several organotin compounds labelled with specific isotopes of tin. Tetrabutyltin-124 was prepared in 80% yield by reacting... 

Compounds labeled with multiple isotopes of the same atom provide the opportunity to observe virtual isomerization reactions that go undetected in conventional studies.There have been relatively few modern studies of these virtual isomerization reactions," " because the reactions themselves are not common and because of difficulties in drawing general conclusions from the observation of the scrambling of isotopic label during solvolysis (Scheme 8). 

Photons with detectable energy differences that are emitted by various radionuclides can be quantified simultaneously, but independently from each other. This allows the use of dual-labeling approaches (4). These experiments will reveal information regarding both the liposomal carrier—labeled with one radionuclide—and the encapsulated compound—labeled with a different radionuclide—after a single injection in the same animal. However,... 

We begin our analysis of excerpt 4F by examining its use of compound labels. You have seen compound labels before. The ubiquitous R group (R, R, R",... or Ri, R2, R3,...) in organic chemistry, used to connote radical or residue (e.g., CHj— or CH3CH2— in R—Br), is one example. Another example is when authors include a bolded number (or bolded number and letter) immediately after the name of a compound in the text or table. Consider the following example, where 1 and 2 are the compound labels ... 

Compound labels, In addition to being concise, focus attention on Important features of a reaction. They allow authors to communicate the versatility and generality of a reaction, mechanism, or scheme efficiently. (See appendix A for more details.)... 

Let s examine the use of compound labels in excerpt 4F. The authors first use compound labels in their eq 1 (our eq 4.1) to illustrate the conversion of an unspecified nitrile 1 to an unspecified tetrazole 2 ... 

Glance ahead to excerpt 4F. Examine the connections between the compound labels used in eq 1 and Table 2. Use these connections to complete eq 1 when 2c... 

In journals such as The Journal of Organic Chemistry and Organic Letters, equations are often included in tables, and the equation and table entries are linked by compound labels. Exercises 4.16 and 4.17 illustrate this convention. 

Imagine that you are in a research group that measures the relative rates of nucleophilic substitution (5 2) reactions. The reactions that you have investigated are listed below. Prepare a table, like Table 1 in exercise 4.16, to summarize these reactions. Include the following equation at the top of the table R-Br + Nu —> R-Nu + Br". Use compound labels to link the equation and table entries. 

In examining Results sections move by move, we looked at how authors refer to hgures and tables, how they use compound labeling, and how they highlight trends in the data. We examined how to report values below detection limits and how to use R to consolidate reactions in a synthesis paper. In this part of the chapter, we analyze a few writing conventions that are characteristic of the entire Results section, including verb tense, voice, and word choice. 

Find out if your set of rules for schemes (generated as part of exercise 5.9) applies to schemes in other articles. Check three articles in The Journal of Organic Chemistry or Organic Letters to see if your rules hold true. In these articles, how do the authors use compound labels and accompanying text to walk the readers through the schemes ... 

Compound labels are common in abstracts. They should follow the numbering scheme used in the main text. (See chapter 4 and appendix A.)... 

Excerpt 8J describes a chemical synthesis. It is quite short (55 words) and includes a graphic. This work (i.e., the work to be presented) is addressed in the first sentence. Compound labels (bolded numbers 1, 2, 3, and 4) are used to link the compounds named in the text to their respective structures in the graphic. Excerpt 8K is longer (150 words). Again, the authors mention their own work in the first sentence (the fractionation and analysis of cranberry fruit for flavonoids). However, flavonoids are not defined, their importance is not emphasized, and no gap is suggested. 

See "Abbreviations, Acronyms, and Compound Labels" in appendix A for more on bolded numbers. 

Standard conventions for using compound labels such as (R,S)-3 should be followed in a poster. (See appendix A.)... 

Column entries Use lowercase for words in columns (e.g., ethanol not Ethanol) unless the word is normally capitalized (e.g., EtOH). Use unbolded font unless the entry is normally bolded (e.g., 2, when 2 is a compound label). 

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