A substance that can react with bromine water and fade it

1. Olefins. Unsaturated hydrocarbons such as alkynes and diolefins.

The class reacts with its derivatives of unsaturated hydrocarbons to discolor bromine water. Such as: ch?=ch?+br?→ch?br-ch?br。

2. React with phenol to form a white precipitate.

3. React with aldehydes and other aldehyde substances to fade bromine water.

4. Due to the extraction, the bromine water fades, and the organic solvent dissolves the bromine orange (or brownish-red).

1) Solvents with a density greater than 1 (carbon tetrachloride.

chloroform, bromobenzene, carbon disulfide, etc.).

2) Solvents with a density of less than 1 (liquid saturated hydrocarbons, straight-run gasoline, benzene and its good sodium homologues, liquid naphthenes, liquid saturated esters).

5. React with alkaline solutions (such as NaOH solution, Na2CO3 solution, etc.) to fade bromine water.

6. It reacts with strong inorganic reducing agents (such as H2S, SO2, Ki and FeSO4, etc.) to fade bromine water.

7. Others: petroleum products (cracking gas, cracking gas, cracking oil, etc.); Natural rubber. Wait.

Bromine water, that is, the aqueous solution of bromine, is orange-yellow or orange, the main component of the solute is bromine, a small amount of reaction with water, the aqueous solution is acidic, with strong oxidation. Bromine water fading mainly occurs in the following situations:

1.Extraction (bromine is more soluble in organic solvents).

This is a physical change, which is mainly manifested in the fading of the water layer and the darker color of the organic layer (mainly orange-red), 2Reacts with alkaline substances or certain salts (bromine water is acidic).

Bromine elementals are converted into bromide and hypobromate ions (or bromate ions) such as sodium hydroxide or sodium carbonate under alkaline conditions.

3.Reacts with silver nitrate solution (silver bromide is insoluble in water).

4.Reacts with certain reducing agents (bromine water exhibits strong oxidation).

a Low-valence sulfur-containing compounds, such as hydrogen sulfide, soluble sulfide, sulfur dioxide, sulfurous acid, sulfite, thiosulfate, etc.

b Elemental metals, such as zinc. metal.

c Substances containing aldehyde groups, which are oxidized to carboxyl groups.

5.An addition reaction occurs.

a Substances containing carbon-carbon double bonds, such as olefins, vegetable oils, cracking gasoline, pyrolysis gas, cracking gas, coal tar, oleic acid, natural rubber (polyisoprene).

b Substances containing carbon-carbon triple bonds, such as alkynes.

Generally, it does not have an addition reaction with the carbonyl group.

6 A substitution reaction occurs.

Substitution reaction occurs with hydrogen atoms on the ortho-position of phenolic hydroxyl groups of phenols, such as phenol, salicylic acid, etc.

The substances that can discolor bromine water are reducing substances and the other are organic substances that are unsaturated or can substitute with bromine.

1) Inorganic substances that can discolor bromine water.

For example, H S: br H S=2Hbr S

so:br so 2h o=h so 2hbrna so:br na so h o=na so 2hbrmg powder (or zn powder, etc.); Br mg = strong bases such as Mgbr Naoh:

br 2naoh = nabr nabro h ona co (or agno equal salt):

br₂+h₂o=hbr+hbro

2hbr na co 2nabr co h ohbro na co = nabro nahco (2) organic matter that can discolor bromine water:

Unsaturated hydrocarbons such as olefins, alkynes, diolefins, styrene, etc., derivatives of unsaturated hydrocarbons, such as enols, enaldehydes, olefins, halogenated olefins, oleic acid, oleate, oleic ester, oil, etc.; Petroleum products, such as cracking gas, cracking gas, cracking gasoline, etc.