Lactones, the English name is lactones, which refers to those containing both carboxyl and hydroxyl groups in the same molecule, which are dehydrated to formorganic compound。Lactone is generated by a molecule itselfesterificationIt is formed by dehydration and is also a molecule after hydrolysis.There is only one ester group (- COO -) in the ring of lactone. If there are more than two ester groups in a ring, it is not lactone butLactide。
Chinese name
lactone
Foreign name
lactones
Definition
Organic compounds with only one ester group in the ring
If there is only one ester group in one ring of the molecule, it is a lactone.Or hydrolyze it, if the molecule occursHydrolysis reactionThe product is a moleculechemical compoundIt's also a two molecule compound.If one molecule is lactone, if two molecules are simple ester compounds, orLactide。[2]Can be generated by simultaneously containinghydroxyl(- OH) andcarboxyl(- COOH) organic matter undergoes esterification reaction to remove a molecule of water and generate.
name
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When lactones are named by traditional methods, the lactones are disassembled to obtain the hydroxyl group of the parent compound, and the first carbon atom next to the carboxyl group (- COOH) is determined asα-Bit, the second is set asβ-，The third isγ-，The fourth isδ-，And so on.The name consists of the position of the cyclic hydroxyl, "-", the number of carbon atoms in the ring and the word "lactone".Examples areγ-Butyrolactone (five membered cyclic lactone formed by 4-hydroxybutyric acid).
The IUPAC name of lactone is to replace the Greek letters in the above name with numbers,α-、β-、γ-、δ-Respectively corresponding to 2 -, 3 -, 4 -, 5 -.γ-The IUPAC name of butyrolactone is "4-butyrolactone".
nature
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Similar in nature to open chain carboxylic acid ester, it reacts with water (in the presence of acid or base), alcohol or ammonia to generate corresponding hydroxy acid, hydroxy ester or hydroxy amide.β-Lactones are usually prepared by the reaction of ketene with aldehydes and ketonesγ-orδ-Lactone can be determined byγ-orδ-Preparation of halogenated acid.Some macrolides isolated from natural materials have biological activity[1]
Lactones are generally insoluble in water,SolubleIn ethanol, ether, etcOrganic solventThe density is generally smaller than that of water.Low lactones are liquid with aromatic smell.
Low molecular weight esters are colorless and volatile aromatic liquids.Higher lactones are usually colorless and odorless waxy solids.Low molecular weight esters can be used as solvents for many organic compounds and varnish.[1]
Hydroxycarboxylic acid can be obtained by heating and dehydration under the catalysis of concentrated sulfuric acid, but its purity is low, and a large number of by-products such as lactides and chain esters are generated, which is rarely used in practice.Dehydrogenation, direct hydrogenation of maleic anhydride and esterification hydrogenation of maleic anhydride can be generally used in industry.[2]
γ-Butyrolactone process consists of reaction system and refining system.1,4-butanediol is generated under the action of catalystγ-Butyrolactone and by-product hydrogen.The by-product hydrogen is sent to the butanediol low-pressure reactor for use after methanation to remove impurities.γ-The butyrolactone first removes the light components, then the heavy components, with a purity of more than 99.5%, and is sent to the finished product tank.[2]
Direct hydrogenation of maleic anhydride
Maleic anhydride enters together with hydrogen after vaporizationHydrogenation reactorUnder the action of copper series catalystγ-Butyrolactone, producing a small amount at the same timeTetrahydrofuran, obtained after coolingγ-Crude butyrolactone, hydrogen recycling;γ-The crude butyrolactone is obtained by distillationγ-Butyrolactone and tetrahydrofuran.
