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Work-up

In chemistry, work-up refers to the series of manipulations required to isolate and purify the product(s) of a chemical reaction. The term is used colloquially to refer to these manipulations, which may include: deactivating any unreacted reagents by quenching a reaction. cooling the reaction mixture or adding an antisolvent to induce precipitation, and collecting or removing the solids by filtration, decantation, or centrifugation. changing the protonation state of the products or impurities by adding an acid or base. separating the reaction mixture into organic and aqueous layers by liquid-liquid extraction. removal of solvents by evaporation. purification by chromatography, distillation or recrystallization. The work-up steps required for a given chemical reaction may require one or more of these manipulations. Workup steps are not always explicitly shown in reaction schemes. Written experimental procedures will describe work-up steps but will usually not formally refer to them as a work-up. The Grignard reaction between phenylmagnesium bromide (1) and carbon dioxide in the form of dry ice gives the conjugate base of benzoic acid (2). The desired product, benzoic acid (3), is obtained by the following work-up: The reaction mixture containing the Grignard reagent is allowed to warm to room temperature in a water bath to allow excess dry ice to evaporate. Any remaining Grignard reagent is quenched by the addition of water. Dilute hydrochloric acid is added to the reaction mixture to protonate the benzoate salts, as well as to dissolve the magnesium salts. White solids of impure benzoic acid are obtained. The benzoic acid is decanted to remove the aqueous solution of impurities, more water is added, and the mixture is brought to a boil with more water added to give a homogeneous solution. The solution is allowed to cool slowly to room temperature, then in an ice bath to recrystallize benzoic acid. The recrystallized benzoic acid crystals are collected on a Buchner funnel and are allowed to air-dry to give pure benzoic acid.

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Related concepts (3)
Ester
In chemistry, an ester is a compound derived from an acid (organic or inorganic) in which the hydrogen atom (H) of at least one acidic hydroxyl group () of that acid is replaced by an organyl group (). Analogues derived from oxygen replaced by other chalcogens belong to the ester category as well. According to some authors, organyl derivatives of acidic hydrogen of other acids are esters as well (e.g. amides), but not according to the IUPAC.
Amide
In organic chemistry, an amide, also known as an organic amide or a carboxamide, is a compound with the general formula , where R, R', and R′′ represent any group, typically organyl groups or hydrogen atoms. The amide group is called a peptide bond when it is part of the main chain of a protein, and an isopeptide bond when it occurs in a side chain, such as in the amino acids asparagine and glutamine. It can be viewed as a derivative of a carboxylic acid () with the hydroxyl group () replaced by an amine group (); or, equivalently, an acyl (alkanoyl) group () joined to an amine group.
Aldehyde
In organic chemistry, an aldehyde (ˈældᵻhaɪd) is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred to as an aldehyde but can also be classified as a formyl group. Aldehydes are a common motif in many chemicals important in technology and biology. Aldehyde molecules have a central carbon atom that is connected by a double bond to oxygen, a single bond to hydrogen and another single bond to a third substituent, which is carbon or, in the case of formaldehyde, hydrogen.

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