Organic reagent

From the beginning of the first century to the middle of the 19th century, qualitative analysis or quantitative analysis was mainly carried out using natural organic matter (such as animal and plant extracts). From the second half of the 19th century to the 1920s, synthetic organic reagents were started, such as nickel, copper and molybdenum with potassium xanthate; aluminum with mordant; and nitrite with diazo coupling Cobalt was detected with α-nitroso-β-naphthol; nickel was examined with diacetyl. After the special effects group was proposed in the 1930s and the analytical functional group theory was put forward in the late 1950s, in order to find special functional analysis functional groups of different ions, a large number of organic reagents were screened, and a number of reagents with practical value were synthesized. Such as copper reagent, new copper reagent, cadmium reagent, hydrazine reagent, hydrazine reagent, etc.). Before the 1950s, the complex chemistry was mainly used for qualitative detection, precipitation separation and gravimetric analysis of the binary chelate precipitation reaction. The complex titration method was mainly used in the early 50s and early 60s. Beginning in the late 1960s, the focus shifted to photometric analysis, while the development of chelate organic solvent extraction. 8-hydroxyquinoline, anthraquinone, anthraquinone, hydroxamic acid, polyphenols, 1,10-phenanthroline, phosphorus-oxygen extractant, β-diketone, triphenylmethane acid dye Various reagents such as xanthene dyes and azo dyes have been widely studied and applied. On the other hand, structural theoretical studies of organic reagents (such as electronic effects, steric effects, and the effects of substituents) have facilitated the development of novel organic reagents, such as heterocyclic azo reagents. Monoazo chromotropic acids and bisazo chromotropic acids have also been developed during this period. In the mid-1970s, adsorbents and chelating resins developed rapidly. Since the 1980s, Chinese analytical chemists have also achieved results in the synthesis and application of asymmetric bisazo chromotropic acid reagents. Organic reagents are widely used in analytical chemistry, mainly in solvents, precipitants, complexing agents, indicators, color developers, and surfactants. In order to adapt to various analytical needs, it is sometimes necessary to purify a certain reagent, liquid organic reagents are often purified by distillation, and solid materials are purified by crystallization or sublimation. A substance having a high vapor pressure, that is, an organic reagent having a lower boiling point and not decomposing at a boiling temperature, is usually subjected to atmospheric distillation; and a substance which is hard to be volatilized and slightly soluble in water, that is, an organic reagent which is decomposed at a higher boiling point or at a boiling temperature Vacuum distillation or steam distillation can be employed. Purification of organic reagents by distillation is a common purification method in the laboratory. The commonly used distillation apparatus generally comprises a distiller, a condenser and a receiver. The auxiliary part also has a heater, a thermometer, a liquid pipe, a cork and the like.