Measuring Methods Available and Examples of Their Applications 1H NMR (Proton Nuclear Magnetic Resonance) the Most Basic Experim

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Measuring methods available and examples of their applications 1H NMR (Proton nuclear magnetic resonance) The most basic experiment is a simple one-dimensional proton NMR spectrum. 1H NMR is a suitable method for purity control, analysis of mixtures and confirmation of molecular structure. It is widely used in the pharmaceutical, medical, and food industries for quality control. The experiment is highly sensitive and measurement time is short. Simple NMR spectra are recorded in solution, and solvent protons must not be allowed to interfere. Deuterated (symbolized as D) solvents for the specific use in NMR are preferred. The most common solvents used include deuterated water, D2O, deuterated acetone, (CD3)2CO, deuterated methanol, CD3OD, deuterated dimethyl sulfoxide, (CD3)2SO, and deuterated chloroform, CDCl3. Approximate minimal concentrations of samples are 0.1 mM for 1H (corresponding 0.015 mg, based on molecular weight 300 and sample volume 0.5 ml). Deuterated solvents permit the use of deuterium frequency-field lock (deuterium lock) to eliminate the effect of the natural drift of the NMR's magnetic field . Proton NMR spectra of most organic compounds are characterized by chemical shifts in the range +15 to -4 ppm and by spin-spin coupling between protons. The integration curve for each proton reflects the abundance of the individual protons. Fig. 1. 1H NMR spectrum of Strychnine in DMSO-d6 with assignment One example of the many applications shows detection of methanol in an alcoholic beverage below. Maximum allowable content of methanol in alcoholic beverages is specified by the Regulation (EC) No. 110/2008; for example, 12 g of methanol per 1 l of ethanol for most fruit distillates. Fig. 2. 1H NMR spectrum of fruit distillate, time of analysis approx. 5 min. .

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Chloroform 18.08.2020.Pdf
Chloroform Chloroform, or trichloromethane, is an organic compound with formula CHCl3. It is a colorless, sweet-smelling, dense liquid that is produced on a large scale as a precursor to PTFE. It is also a precursor to various refrigerants. It is one of the four chloromethanes and a trihalomethane. It is a powerful anesthetic, euphoriant, anxiolytic and sedative when inhaled or ingested. Formula: CHCl₃ IUPAC ID: Trichloromethane Molar mass: 119.38 g/mol Boiling point: 61.2 °C Density: 1.49 g/cm³ Melting point: -63.5 °C The molecule adopts a tetrahedral molecular geometry with C3v symmetry. Chloroform volatilizes readily from soil and surface water and undergoes degradation in air to produce phosgene, dichloromethane, formyl chloride, carbon monoxide, carbon dioxide, and hydrogen chloride. Its half-life in air ranges from 55 to 620 days. Biodegradation in water and soil is slow. Chloroform does not significantly bioaccumulate in aquatic organisms. Production:- In industry production, chloroform is produced by heating a mixture of chlorine and either chloromethane (CH3Cl) or methane (CH4). At 400–500 °C, a free radical halogenation occurs, converting these precursors to progressively more chlorinated compounds: CH4 + Cl2 → CH3Cl + HCl CH3Cl + Cl2 → CH2Cl2 + HCl CH2Cl2 + Cl2 → CHCl3 + HCl Chloroform undergoes further chlorination to yield carbon tetrachloride (CCl4): CHCl3 + Cl2 → CCl4 + HCl The output of this process is a mixture of the four chloromethanes (chloromethane, dichloromethane, chloroform, and carbon tetrachloride), which can then be separated by distillation. Chloroform may also be produced on a small scale via the haloform reaction between acetone and sodium hypochlorite: 3 NaClO + (CH3)2CO → CHCl3 + 2 NaOH + CH3COONa Deuterochloroform[ Deuterated chloroform is an isotopologue of chloroform with a single deuterium atom.
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