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The 13 C NMR spectra were recorded at several spectrometers with resonance frequencies ranging from 15 MHz to 100 MHz and a resolution ranging from 0.025 to 0.045 ppm. Spectra were acquired using a pulse flip angle of 22.5 – 45 degrees and a pulse repetition time of 4 – 7 seconds. [4]
The Zeisel determination or Zeisel test is a chemical test for the presence of esters or ethers in a chemical substance. [1] [2] [3] [4]It is named after the Czech chemist Simon Zeisel (1854–1933).
While 1D NMR is more straightforward and ideal for identifying basic structural features, COSY enhances the capabilities of NMR by providing deeper insights into molecular connectivity. The two-dimensional spectrum that results from the COSY experiment shows the frequencies for a single isotope, most commonly hydrogen (1 H) along both axes.
Gutmann, a chemist renowned for his work on non-aqueous solvents, described an acceptor-number scale for solvent Lewis acidity [4] with two reference points relating to the 31 P NMR chemical shift of Et 3 PO in the weakly Lewis acidic solvent hexane (δ = 41.0 ppm, AN 0) and in the strongly Lewis acidic solvent SbCl 5 (δ = 86.1 ppm, AN 100).
2,4-Dihydroxybenzoic acid (β-resorcylic acid) is a dihydroxybenzoic acid. As a resorcylic acid, it is one of the three isomeric crystalline acids that are both carboxyl derivatives of resorcinol and dihydroxy derivatives of benzoic acid. [4] Synthesis from resorcinol is via the Kolbe-Schmitt reaction. [5]
Ethidium bromide (or homidium bromide, [2] chloride salt homidium chloride) [3] [4] is an intercalating agent commonly used as a fluorescent tag (nucleic acid stain) in molecular biology laboratories for techniques such as agarose gel electrophoresis. It is commonly abbreviated as EtBr, which is also an abbreviation for bromoethane.
It reacts with acetylacetone in the presence of cesium carbonate to give 3-(4-bromophenylthio)pentane-2,4-dione. 4,4'-Dibromophenyl disulfide is also produced as the intermediate. [5] Like other thiols, it reacts with silver nitrate to produce silver 4-bromothiophenolate. [6]
DIPEA is a sterically hindered organic base that is commonly employed as a proton scavenger. Thus, like 2,2,6,6-tetramethylpiperidine and triethylamine, DIPEA is a good base but a poor nucleophile, DIPEA has low solubility in water, which makes it very easily recovered in commercial processes, a combination of properties that makes it a useful organic reagent.