The Zerewitinoff determination or Zerevitinov determination is a quantitative chemical test for the determination of active hydrogens in a chemical substance. [1] A sample is treated with the Grignard reagent, methylmagnesium iodide, which reacts with any acidic hydrogen atom to form methane. This gas can be determined quantitatively by measuring its volume. For example:
A methyl group is an alkyl derived from methane, containing one carbon atom bonded to three hydrogen atoms — CH3. In formulas, the group is often abbreviated Me. Such hydrocarbon groups occur in many organic compounds. It is a very stable group in most molecules. While the methyl group is usually part of a larger molecule, it can be found on its own in any of three forms: anion, cation or radical. The anion has eight valence electrons, the radical seven and the cation six. All three forms are highly reactive and rarely observed.
In chemistry, pH is a scale used to specify how acidic or basic a water-based solution is. Acidic solutions have a lower pH, while basic solutions have a higher pH. At room temperature, pure water is neither acidic nor basic and has a pH of 7.
Stoichiometry is the calculation of reactants and products in chemical reactions.
Tetrahydrofuran (THF), or oxolane, is an organic compound with the formula (CH2)4O. The compound is classified as heterocyclic compound, specifically a cyclic ether. It is a colorless, water-miscible organic liquid with low viscosity. It is mainly used as a precursor to polymers. Being polar and having a wide liquid range, THF is a versatile solvent.
A substance is anhydrous if it contains no water. Many processes in chemistry can be impeded by the presence of water, therefore, it is important that water-free reagents and techniques are used. In practice, however, it is very difficult to achieve perfect dryness; anhydrous compounds gradually absorb water from the atmosphere so they must be stored carefully.
Gravimetric analysis describes a set of methods used in analytical chemistry for the quantitative determination of an analyte based on its mass. The principle of this type of analysis is that once an ion's mass has been determined as a unique compound, that known measurement can then be used to determine the same analyte's mass in a mixture, as long as the relative quantities of the other constituents are known.
Coulometry determines the amount of matter transformed during an electrolysis reaction by measuring the amount of electricity consumed or produced. It can be used for precision measurements of charge, and the Ampere even used to have a coulometric definition. However, today coulometry is mainly used for analytical applications. Coulometry is a group of techniques in analytical chemistry. It is named after Charles-Augustin de Coulomb.
Elemental analysis is a process where a sample of some material is analyzed for its elemental and sometimes isotopic composition. Elemental analysis can be qualitative, and it can be quantitative. Elemental analysis falls within the ambit of analytical chemistry, the set of instruments involved in deciphering the chemical nature of our world.
Devarda's alloy, is an alloy of aluminium (44% – 46%), copper (49% – 51%) and zinc (4% – 6%).
In chemistry, a chemical test is a qualitative or quantitative procedure designed to identify, quantify, or characterise a chemical compound or chemical group.
The Zeisel determination or Zeisel test is a chemical test for the presence of esters or ethers in a chemical substance. It is named after the Czech chemist Simon Zeisel (1854–1933). In a qualitative test a sample is first reacted with a mixture of acetic acid and hydrogen iodide in a test tube. The ensuing reaction results in the cleavage of the ether or the ester into an alkyl iodide and respectively an alcohol or a carboxylic acid.
Carbon-13 (C13) nuclear magnetic resonance is the application of nuclear magnetic resonance (NMR) spectroscopy to carbon. It is analogous to proton NMR and allows the identification of carbon atoms in an organic molecule just as proton NMR identifies hydrogen atoms. As such 13C NMR is an important tool in chemical structure elucidation in organic chemistry. 13C NMR detects only the 13
C
isotope of carbon, whose natural abundance is only 1.1%, because the main carbon isotope, 12
C
, is not detectable by NMR since its nucleus has zero spin.
Uranyl zinc acetate (ZnUO2(CH3COO)4) is a compound of uranium.
Wet chemistry is a form of analytical chemistry that uses classical methods such as observation to analyze materials. It is called wet chemistry since most analyzing is done in the liquid phase. Wet chemistry is also called bench chemistry since many tests are performed at lab benches.
In analytical chemistry, quantitative analysis is the determination of the absolute or relative abundance of one, several or all particular substance(s) present in a sample.
Deoxygenation is a chemical reaction involving the removal of oxygen atoms from a molecule. The term also refers to the removal molecular oxygen (O2) from gases and solvents, a step in air-free technique and gas purifiers. As applied to organic compounds, deoxygenation is a component of fuels production as well a type of reaction employed in organic synthesis, e.g. of pharmaceuticals.
Physical organic chemistry, a term coined by Louis Hammett in 1940, refers to a discipline of organic chemistry that focuses on the relationship between chemical structures and reactivity, in particular, applying experimental tools of physical chemistry to the study of organic molecules. Specific focal points of study include the rates of organic reactions, the relative chemical stabilities of the starting materials, reactive intermediates, transition states, and products of chemical reactions, and non-covalent aspects of solvation and molecular interactions that influence chemical reactivity. Such studies provide theoretical and practical frameworks to understand how changes in structure in solution or solid-state contexts impact reaction mechanism and rate for each organic reaction of interest.
Nuclear magnetic resonance spectroscopy of stereoisomers most commonly known as NMR spectroscopy of stereoisomers is a chemical analysis method that uses NMR spectroscopy to determine the absolute configuration of stereoisomers. For example, the cis or trans alkenes, R or S enantiomers, and R,R or R,S diastereomers.
Trimethyl orthoformate is the simplest orthoester. It is a reagent used in organic synthesis for the introduction of a protecting group for aldehydes. The product of reaction of an aldehyde with trimethyl orthoformate is an acetal. In general cases, these acetals can be deprotected back to the aldehyde by using hydrochloric acid.
Sanger–Black apparatus is a piece of chemical laboratory ware used for quantitative and semi-quantitative determination of arsenic element in the solution. It is constituted by glass bottle of volume ca. 30 mL, sealed with rubber stopper with one or two holes. Through one hole a thistle tube is inserted, almost reaching the bottom, for filling the bottle (what can be done also when the stopper is taken out – for semi-quantitative determination). The second, S-shaped tube is for outflow of the gases and joined by another rubber stopper to a bulg tube, with bulb containing pre-dried cotton as adsorbent, presumably intended for homogenizing the gas flow. A thin reagent paper, impregnated with mercury(II) chloride (nowadays replaced by mercury(II) bromide) or silver(I) nitrate, is placed in the open end of the bulb tube. If the semi-quantitative variant is to be performed, the paper is put in the (only) thistle tube – i. e., vertically, not horizontally. During the test ca. 3 g of Zn granules are placed into the bottle, just below the end of thistle tube, and then acid solution is added (ca. 15 mL; authors recommend that HCl is preferable to H2SO4). About 10 minutes are required to let H2 flow along the reagent paper, while this flow and moisture content inside it is stabilizing. Then the sample is introduced, and in case of sample solution containing arsenic the paper becomes more or less stained.