1,3-Dichlorobenzene is a colorless liquid with a pungent odor. Insoluble in water, soluble in alcohol and ether. Toxic to human body, irritating to eyes and skin. It is combustible and can undergo chlorination, nitrification, sulfonation, and hydrolysis reactions. It reacts violently with aluminum and is used in organic synthesis.

English name: 1,3-Dichlorobenzene

English alias: 1,3-Dichloro Benzene; m-Dichloro Benzene; m-Dichlorobenzene

MDL: MFCD00000573

CAS Number: 541-73-1

Molecular formula: C6H4Cl2

Molecular weight: 147.002

Physical data：

1. Properties: colorless liquid with pungent odor.
2. Melting point (℃): -24.8
3. Boiling point (℃): 173
4. Relative density (water = 1): 1.29
5. Relative vapor density (air=1): 5.08
6. Saturated vapor pressure (kPa): 0.13 (12.1℃)
7. Heat of combustion (kJ/mol): -2952.9
8. Critical temperature (℃): 415.3
9. Critical pressure (MPa): 4.86
10. Octanol/water partition coefficient: 3.53
11. Flash point (℃): 72
12. Ignition temperature (℃): 647
13. Upper explosion limit (%): 7.8
14. Lower explosion limit (%): 1.8
15. Solubility: insoluble in water, soluble in ethanol and ether, and easily soluble in acetone.
16. Viscosity (mPa·s, 23.3ºC): 1.0450
17. Ignition point (ºC): 648
18. Heat of evaporation (KJ/mol, b.p.): 38.64
19. Heat of formation (KJ/mol, 25ºC, liquid): 20.47
20. Heat of combustion (KJ/mol, 25ºC, liquid): 2957.72
21. Specific heat capacity (KJ/(kg·K), 0ºC, liquid): 1.13
22. Solubility (%, water, 20ºC): 0.0111
23. Relative density (25℃, 4℃): 1.2828
24. Normal temperature refractive index (n25): 1.5434
25. Solubility parameter (J·cm-3) 0.5: 19.574
26. Van der Waals area (cm2·mol-1): 8.220×109
27. Van der Waals volume (cm3·mol-1): 87.300
28. The liquid phase standard claims heat (enthalpy) (kJ·mol-1): -20.7
29. Liquid phase standard hot melt (J·mol-1·K-1): 170.9
30. The gas phase standard claims heat (enthalpy) (kJ·mol-1): 25.7
31. Standard entropy of gas phase (J·mol-1·K-1): 343.64
32. Standard free energy of formation in gas phase (kJ·mol-1): 78.0
33. Gas phase standard hot melt (J·mol-1·K-1): 113.90

Storage method:
Precautions for storage, store in a cool, ventilated warehouse. Keep away from fire and heat sources. Keep the container tightly closed. It should be stored separately from oxidants, aluminum, and edible chemicals, and avoid mixed storage. Equipped with the appropriate variety and quantity of fire equipment. The storage area should be equipped with leakage emergency treatment equipment and suitable storage materials.

resolve resolution:
The preparation methods are as follows. Using chlorobenzene as a raw material for further chlorination, p-dichlorobenzene, o-dichlorobenzene and m-dichlorobenzene are obtained. The general separation method uses mixed dichlorobenzene for continuous distillation. The para- and meta-dichlorobenzene is distilled from the top of the tower, p-dichlorobenzene is precipitated by freezing and crystallization, and the mother liquor is then rectified to obtain meta-dichlorobenzene. The o-dichlorobenzene is flash distilled in the flash tower to obtain o-dichlorobenzene. At present, the mixed dichlorobenzene adopts the method of adsorption and separation, using molecular sieve as the adsorbent, and the gas phase mixed dichlorobenzene enters the adsorption tower, which can selectively adsorb p-dichlorobenzene, and the residual liquid is meta and ortho dichlorobenzene. Rectification to obtain m-dichlorobenzene and o-dichlorobenzene. The adsorption temperature is 180-200°C, and the adsorption pressure is normal pressure.

1. Meta-phenylenediamine diazonium method: meta-phenylenediamine is diazotized in the presence of sodium nitrite and sulfuric acid, the diazotization temperature is 0～5℃, and the diazonium liquid is hydrolyzed in the presence of cuprous chloride to produce intercalation Dichlorobenzene.

2. Meta-chloroaniline method: Using meta-chloroaniline as the raw material, diazotization is carried out in the presence of sodium nitrite and hydrochloric acid, and the diazonium liquid is hydrolyzed in the presence of cuprous chloride to generate meta-dichlorobenzene.

Among the above several preparation methods, the most suitable method for industrialization and lower cost is the adsorption separation method of mixed dichlorobenzene. There are already production facilities in China for production.

The main purpose:
1. Used in organic synthesis. The Friedel-Crafts reaction between m-dichlorobenzene and chloroacetyl chloride yields 2,4,ω-trichloroacetophenone, which is used as an intermediate for the broad-spectrum antifungal drug miconazole. The chlorination reaction is carried out in the presence of ferric chloride or aluminum mercury, mainly producing 1,2,4-trichlorobenzene. In the presence of a catalyst, it is hydrolyzed at 550-850°C to generate m-chlorophenol and resorcinol. Using copper oxide as a catalyst, it reacts with concentrated ammonia at 150-200°C under pressure to generate m-phenylenediamine.
2. Used in dye manufacturing, organic synthesis intermediates and solvents.