What are the conditions for metathesis reaction

Metathesis reaction can be divided into the following five types, in essence, in addition to the requirements for the products, the occurrence of the metathesis reaction also has certain requirements for the reactants, that is, when there is no acid in the reactants, the reactants should be soluble in water, which is summarized and compared as follows:

Acid + metal oxide salt + water.

Acid + alkali salt + water.

Acid + Salt New acid + new salt.

Alkali + salt New alkali + new salt (reactants should be soluble in water).

Salt + salt New salt + new salt (reactants should be soluble in water).

The three conditions under which metathesis reactions can occur (i.e., precipitation or gas or water in the product) have effectively guided scientific experiments and production practices for a long time. It has been shown through practice that a substance or resalt can be precipitated in the reaction due to temperature difference or concentration, and metathesis reaction can also occur.

The 2005 Nobel Prize in Chemistry was awarded to three scientists for their achievements in the study of olefin metathesis reactions. The three scientists were Yves of the French Petroleum Institute. Chauvin, Robert of the Massachusetts Institute of Technology.

Grubb and Richard of Caltech, California. Schrock. They discovered Chauvin's mechanism of "exchange dance partners" for olefin metathesis reactions, namely:

The metathesis reaction of olefins is a process in which the carbon-carbon double bonds in olefins are dismantled, exchanged, and recombined under the catalytic action of metal carbene compounds to form new molecules.

1) Basic oxide acid salt H2O

fe2o3+6hcl==2fecl3+3h2o；fe2o3+3h2so4==fe2(so4)3+3h2o

cuo+h2so4==cuso4+h2o；zno+2hno3==zn(no3)3+h2o

2) Alkaline acid salt H2O

cu(oh)2+2hcl==cucl2+2h2o；cu(oh)2+h2so4==cuso4+2h2o

naoh+hcl==nacl+h2o；2naoh+h2so4==na2so4+2h2o

naoh+hno3==nano3+h2o；mg(oh)2+2hno3==mg(no3)2+2h2o

ba(oh)2+h2so4==baso4↓+2h2o

3) Acid salt, new salt, new acid.

caco3+2hcl==cacl2+h2o+co2↑；na2co3+2hcl==2nacl+h2o+co2↑

hcl+agno3==agcl↓+hno3；h2so4+bacl2==baso4↓+2hcl

ba(no3)2+h2so4==baso4↓+2hno3

nahco3+hcl==nacl+h2o+co2↑

Occurrence conditions

Basic conditions: The two substances in which the metathesis reaction takes place can exchange ions in an aqueous solution and combine to form a substance that is difficult to ionize (precipitate, gas or weak electrolyte).

1. Basic oxide + acid: the acidity of the acid is strong (such as HCl, H2SO4, HNO3, etc.), and the reaction can occur.

2. Acid + alkali (neutralization reaction): when the acid and alkali are weak, no reaction occurs.

3. Acid + salt: strong acid to weak acid; There is precipitation after the exchange of ions; strong acids react with carbonates; A reaction can occur when one condition is met.

4. Alkali + salt: strong alkali reacts with ammonium salt; Both reactants are soluble, and there are one of three after the exchange of ions: precipitation, water, and gas; A reaction can occur when one condition is met.

5. Salt + salt: both reactants are soluble, and there is one of the three of precipitation, water and gas after the exchange of ions, and the reaction can occur if one condition is met.