The concept of organic chemistry in hydrolysis reaction refers to the reaction between water and another compound, which is decomposed into two parts+To a part of it, andhydroxyl(- OH) is added to another part, thus obtaining two or more newchemical compoundReaction process;The concept of inorganic chemistry isWeak acid radicalOr weak base ions react with water to formweak acidandHydroxyl ion（OH-）(orweak alkaliandHydrogen ion（H+））。It is widely used in industryorganic compoundThe main products are alcohols and phenols.Hydrolysis reaction isNeutralization reactionoresterificationThe reverse reaction of.Hydrolysis of most organic compounds is difficult to proceed smoothly only with water, generally under alkaline or acidic conditions.
Definition: salt in solutionionizationIons and H ionized by water+And OH-Associative generationWeak electrolyteReaction.
Inorganics are usually decomposed in waterComplex decompositionIn the process, water molecules are also decomposed and combined with the hydrolyzed material fragments to form new substances.
Hydrolysis of ammonium chloride will produce hydrochloric acid and ammonia (acidic after hydrolysis): NHfourCl+HtwoO=NHthree·HtwoO+HCl[1]
Hydrolysis reaction is a reaction between water and another compound, which is decomposed into two parts. The hydrogen atom in water is added to one part, and the hydroxyl is added to the other part, so that two or more new compounds can be obtained.This concept of hydrolysis reaction is applicable to the hydrolysis of halogenated hydrocarbons and esters in organic chemistry, as well as covalent halides such as SiClfour、TiClfourHydrolysis reaction.However, in inorganic chemistry, the concept of hydrolysis reaction is often expressed as: in solution, ions ionized by salt and H ionized by water+Or OH-The reaction of ion combination to form weak electrolyte or the interaction of ions generated by salt dissociation with water will shift the dissociation balance of water, thus affecting the acid-base effect (reaction) of the solution.In fact, the above two expressions are not comprehensive enough, because some covalent halides and halide interconnects cannot be called salts, but they can undergo strong hydrolysis reactions.Therefore, the hydrolysis reaction can be expressed as: in the aqueous solution, when the cation (anion) of the ionic compound or the positive (negative) atom of the covalent compound has strong enough polarization ability to break the O-H bond in the water molecule when interacting with the water molecule, the positive (negative) atom of the cation (anion) or covalent compoundThe atom of H+combines with OH group (H+ion), generates insoluble substances or weak electrolytes (complex ions, weak acids, weak bases, etc.), and emits H+(Discharge OH-Group).It can be seen that the cation with weak polarization ability is like the metal ion Li of the first main group+、Na+、K+、Rb+、Cs+and metal ion Ca of the second main group2+、Sr2+、Ba2+The O-H bond of water molecule cannot be broken, so it is generally said that these ions do not undergo hydrolysis reaction, but only exist in the form of hydrated ions in aqueous solution.Strong acid anions such as Cl-、Br-、NOthree-、ClOfour-Plasma can not break the O-H bond of water molecules, so it is generally believed that these anions will not undergo hydrolysis reaction.From the perspective of acid base proton theory, the (hydrated) cations or anions that undergo hydrolysis are weak proton acids or weak proton bases. Therefore, in the acid base proton theory, the hydrolysis reaction is essentially the proton transfer reaction between amphoteric water molecules, proton acids and proton bases.In the acid-base electronic theory, the hydrolysis reaction is essentially an acid-base reaction between Lewis acid and Lewis base.[3]
Organic hydrolysis reaction
The molecules of organic matter are generally large, and acid or base is required as a catalyst for hydrolysis, and sometimes bioactive enzyme is also used as a catalyst.
① In acidic aqueous solution, fat will be hydrolyzed into glycerol and fatty acid;Starch will be hydrolyzed intomalt dust、glucoseEtc;proteinIt can be hydrolyzed into amino acids and other substances with low molecular weight.
② In alkaline aqueous solution, fat will decompose intoglycerolAnd solid fatty acid salts, namely soap, so this hydrolysis is also calledSaponification reaction。
Hydrolysis of organic matter is widely used in industry, mainly producing alcohol and phenol.Hydrolysis reaction is neutralization oresterificationThe reverse reaction of.Hydrolysis of most organic compounds is difficult to proceed smoothly only with water.According to the nature of the hydrolysate, the hydrolytic agent can be sodium hydroxide aqueous solution, dilute acid or concentrated acid, or sometimesPotassium hydroxide、calcium hydroxide、Sodium bisulfiteAnd other aqueous solutions.This is called alkali hydrolysis and acid hydrolysis.Hydrolysis can be operated intermittently or continuouslyKettle reactorThe latter is more usefulTower reactor。[2]
Organic hydrolysis reaction
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Hydrolysis of halides
Generally, sodium hydroxide aqueous solution is used as the hydrolysis agent, and the general reaction formula is as follows:
R-X+HtwoO→R-OH+HX
Ar-X+2HtwoO→Ar-OH+HX+HtwoIn formula O, RAr and X respectively representalkyl、Aryl group、halogen。Halogens on the aliphatic chain are generally active and can be hydrolyzed under mild conditions, such asBenzyl chloridesystemBenzyl alcohol；The halogen on the aromatic ring is ortho or para positionedNitroDuring activation, hydrolysis is easy, such as fromP-NitrochlorobenzeneTo prepare p-nitrophenol sodium.[2]
Hydrolysis of esters
Oils and fats can be hydrolyzed under acid or alkali catalysis
① Hydrolysis under acid conditions
Hydrolysis to glycerol (glycerol) and higher fatty acids under acidic conditions
② Hydrolysis under alkaline conditions
Hydrolysis to glycerol (glycerol) and higher fatty acid salt under alkaline conditions
Both hydrolyses produce glycerol.
The hydrolysis of oil under alkaline conditions is called saponification reaction.
In industry, soap is produced by saponification of oil
The alkyl sulfate obtained from the reaction of low-carbon olefins with concentrated sulfuric acid can be hydrolyzed to obtain low-carbon alcohol by adding acid.[2]
Generally, it is not easy to carry out. It needs to be alkali fused first, that is, molten sodium hydroxide reacts with sodium arylsulfonate at high temperature to generate sodium phenolate, which can be hydrolyzed by adding acid to generate phenol.asSodium 2-naphthalenesulfonateIt is obtained by hydrolysis after normal pressure alkali melting at 300~340 ℃2-Naphthol。Some aromatic sulfonates also need the mixed alkali of sodium hydroxide and potassium hydroxide as the reagent for alkali melting.When aromatic sulfonates are more active, sodium hydroxide aqueous solution can be used for alkali melting at a lower temperature.[2]
Hydrolysis of amine
Aliphatic amines and aromatic amines are generally difficult to hydrolyze.The aromatic primary amine is usually first mixed in dilute sulfuric acidDiazotizationgenerateDiazonium saltAnd reheat to hydrolyze the diazonium salt.As fromO-AminoanisolesystemGuaiacol。[2]
