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| Arrhenius equation | predicts that the rate of reaction increases if the temperature is raised |
| Aspirator | is a device that produces vacuum by means of the Venturi effect. In an aspirator, fluid (liquid or gaseous) flows through a tube which then narrows. When the tube narrows, the fluid's speed increases, and because of the Venturi effect, its pressure decreases. Vacuum is taken from this point |
| Atropisomer | is a stereoisomer that results from hindered rotation about a single bond where the steric strain barrier to rotate is high enough to isolate the different conformers. |
| Beer-Lambert-Law | is the basic law for all absorption processes (A=ecl). It states that the absorbance of a sample is directly proportional to the concentration of the solute in the sample, the pathlength and the molar extinction coefficient (e). The law only applies for very diluted solution (<10-4 mol/L). |
| Bathochromic shift | is a shift to higher wavelength in the UV-Vis spectrum |
| Boiling point | is the temperature when a liquid becomes a gas. It depends highly on the surrounding pressure |
| Catalyst | is a compound that increases the rate of the reaction by lowering the activation energy for a chemical reaction, but does not change the yiel |
| Chromatography | is a technique to separate compounds from each other. It is based on the distribution various compounds between the mobile phase (see below) and the stationary phase (see below). |
| Chromophore | is a chemical group that absorbs light at a specific wavelength and so imparts color to a molecule i.e. carbonyl group or azo group |
| Condensation point | is the temperature at which the conversion of a substance from the vapor state to a denser liquid or solid state takes place usually initiated by a reduction in temperature of the vapor |
| Coupling constant | characterizes the line spacing within a multiplet in a 1H-NMR spectrum, which permits conclusions about the distance and the angle of interaction of the coupling partners |
| Decant(ing) | the process in the laboratory when a liquid is transferred into a different container and the solid is left behind |
| Dew point |
the temperature at which a vapor begins to condense (which is not equal to the boiling point!) |
| Diastereomer | is a stereoisomer of a compound having two or more chiral centers that is not a mirror image of another stereoisomer of the same compound i.e borneol and isoborneol |
| Disproportionation | refers to the transformation of a substance into two or more dissimilar substances usually by simultaneous oxidation and reduction i.e. Mn(III) forms Mn(II) and Mn(IV). |
| Distillation | is a technique to purify liquids based on different boiling points |
| Distribution coefficent | also called partition coefficient. Quantifies the distribution of a compound between two different phases (K=c1/c2) |
| Emulsion | is a suspension of finely divided particles in a continuous medium in which the particles are approximately 5 to 5,000 Å in size, do not settle out of the substance rapidly, and are not readily filtered i.e. oil and vinegar in a vinegrette, or fat in water in milk |
| Enantiomer | is a molecule that is not superimposable on its mirror image, related to chirality |
| Enantiomeric excess | is the ratio of one enantiomer to the other enantiomer in a mixture (abbreviated: e.e. or ee). It is often used in context of asymmetric synthesis. Related: diastereomeric excess. |
| Exclusion rule | describes the fact that a molecule with a center of inversion has peaks either in the IR or in the Raman spectrum, but not in both. |
| Extraction | is a process to isolate a compound from a mixture by either temporary chemical modification or distribution within two layers. |
| FID | =Flame Ionization Detector, a detector used in GC chromatography, very sensitive but destroys the sample due to combustion |
| Freezing point | is the temperature at which a liquid becomes a solid. Its depression can be used to determine the molecular weight of compounds (=collagative property) |
| Hammond Postulate | If two states, as for example, a transition state and an unstable intermediate, occur consecutively during a reaction process and have nearly the same energy content, their interconversion will involve only a small reorganization of the molecular structures. That is, along the reaction coordinate, species with similar energies also have similar structures |
| Heterogeneous | is a system that consists of at least two phases (solid-liquid) |
| Homogeneous | is a system that consists of only one phase i.e. solution |
| HOMO | is the highest occupied molecular orbital in a molecule |
| Hygroscopic | is a compound that absorbs water from the air or a solution, nature of drying agents |
| Hyperchromic | Increased absorption of UV-Vis light (opposite: hypochromic) |
| Hypsochromic shift | is the shift to lower wavelength in the UV-Vis spectrum (opposite: bathochromic) |
| In-situ | refers to the synthesis of a reactive intermediate, which is not isolated since it is too difficult or too dangerou |
| Infrared spectroscopy | is a spectroscopic technique to identify functional groups, looks at vibrational modes of the molecule. The modern instruments are FTIR instruments. |
| Lachrymator | a compound that makes the eyes fill with tears but does not damage them (“teargas”) |
| Le Châtelier Principle | describes equilibrium reactions and how to influence them |
| Lock-and-Key method | describes the selectivity of enzymes towards certain substrates over others |
| LUMO | lowest unoccupied molecular orbital |
| Melting point | is the temperature at which a solid becomes a liquid, usually reported as a range |
| Metallorganic | a compound that possesses carbon but no direct M-C bond i.e. sodium acetate |
| Methylene chloride | =dichloromethane |
| Mobile phase | is a term used in chromatography. It consists usually of an organic solvent (or mixture) in column chromatography |
| Mother liquor | the solution that was separated from the crystals |
| Neat | a term often used in IR spectroscopy, means that only the pure compound was place in the IR beam |
| NMR spectroscopy | is a spectroscopic technique to identify functional groups and structure of a compound. It looks at behavior of nuclear spins in an external magnetic field, frequently used as 1H or 13C-NMR spectroscopy in organic laboratories |
| Oligomer | is a polymer or polymer intermediate containing relatively few structural units (more than two units) i.e. dimer, trimer |
| Organometallic | the compound has at least one metal-carbon bond i.e. Grignard reagent, ferrocene, etc |
| Petroleum ether | (also called Petrolether or ligroin) is a mixture of different hydrocarbons. The name does not refer to oxygen containing compounds but much more on its volatility |
| Pyrolysis | is the process where organic compounds decompose when heated without burning. |
| Pyrophoric | means that a compound catches on fire when it comes in contact with air. Many finely divided metal powder or strong reducing reagents react like this i.e. Raney Nickel, LiAlH4 |
| PTC | =Phase Transfer Catalysis, utilizes a catalyst which is able to transport an ion from one phase (usually aqueous) into the other phase (organic). |
| Quenching | a reaction is terminating by deactivating reactive intermediates |
| Racemic | a mixture that is composed of equal amounts of dextrorotatory and levorotatory forms of the same compound and is not optically active |
| Recrystallization | is a technique used to purify solids based on different solubilities of the impurity and the target compound. |
| Reflux | implies that a solution/solvent is heated to a boil while maintaining its volume constant. This is usually accomplished by using a device to catch the solvent vapors i.e. condenser |
| Refractive Index | is a physical property that quantifies the refraction of light by a solid or liquid. It highly depends on the temperature and the wavelength it is observed |
| Retardation factor | is the ratio of how far the center of a spot traveled compared to the solvent front (=Rf-value) |
| Retention time | is the time interval that passed between the sample injection and the appearance of the peak maximum |
| Rinsing/Rinse | refers to the washing of a solid with small amounts of cold solvent to remove mother liquor and impuries from the surface |
| Saturated solution | is a solution that contains the maximum amount of solute at a given temperature. |
| Seeding | is a technique to initiate crystallization from saturated or super-saturated solutions |
| Split-mode | refers to the fact that only a small amount of the sample is actually introduced to the GC column |
| Stationary phase | is a term used in chromatography. It refers to the part, which absorbs the compound. The stronger the interaction is, the longer the compound requires moving through the column |
| Sublimation point | is the temperature at which a solid evaporates without melting first |
| Superheating | the process at which a liquid is heated above its boiling point without vaporization. Can be avoided by adding boiling stones, boiling sticks or a spin vane |
| Supersaturated | is a solution that contains more than the maximum amount of solute at a given temperature. Often causes problems during the recrystallization process. |
| TCD | =Thermal Conductivity Detector, less sensitive than FID, but allows to collect sample |
| Trituration | commonly refers to the grinding of powders in a pestle or mortar. It is a method to induce crystallization of a pure compound from an impure oil or the process of separating two solids by selectively dissolving one compound while the other is insoluble. |
| UV-Vis spectroscopy | is a technique to investigate conjugation within molecules. Often used for colored compounds. Looks at the excitation of electrons from a bonding to an anti-bonding orbital |
| Vacuum filtration | is a filtration technique that permits to separate a solid from a liquid. The vacuum increases the flow rate of the mother liquor through the filter paper. Not suitable for low boiling or hot solvents! |
| Washing | is a process to remove small amounts of byproducts or a catalyst from a reaction mixture. |
| Zaitsev Rule | predicts the formation of an alkene based on thermodynamic stability: the alkene with the highest the degree of substitution is preferentially formed under thermodynamic conditions. |