IUPAC Name: (2,4-Difluorophenyl)hydrazine 
Following is the structure of 2,4-Difluorophenylhydrazine hydrochloride (CAS NO.51523-79-6):
                           
Empirical Formula: C₆H₇ClF₂N₂
Molecular Weight: 180.583 g/mol
Flash Point: 65.7 °C
Melting point: 210 °C (dec.)
Enthalpy of Vaporization: 42.13 kJ/mol
Boiling Point: 185.1 °C at 760 mmHg
Vapour Pressure: 0.71 mmHg at 25 °C
Appearance of 2,4-Difluorophenylhydrazine hydrochloride (CAS NO.51523-79-6): white to light yellow crystal powde
Product Categories of 2,4-Difluorophenylhydrazine hydrochloride (CAS NO.51523-79-6): Aromatic Hydrazides, Hydrazines, Hydrazones and Oximes; Phenylhydrazine; Phenyls & Phenyl-Het;Hydrazines; Nitrogen Compounds; Organic Building Blocks
Canonical SMILES: C1=CC(=C(C=C1F)F)NN
InChI: InChI=1S/C6H6F2N2/c7-4-1-2-6(10-9)5(8)3-4/h1-3,10H,9H2
InChIKey: RLZUIPTYDYCNQI-UHFFFAOYSA-N

 2,4-Difluorophenylhydrazine hydrochloride (CAS NO.51523-79-6) hasn't been listed as a carcinogen by ACGIH, IARC, NTP, or CA Prop 65.

Hazard Codes: Xn,Xi
Risk Statements: 20/21/22-36/37/38 
R20/21/22:Harmful by inhalation, in contact with skin and if swallowed. 
R36/37/38:Irritating to eyes, respiratory system and skin.
Safety Statements: 26-36/37-36/37/39-22 
S26: In case of contact with eyes, rinse immediately with plenty of water and seek medical advice. 
S36/37:Wear suitable protective clothing and gloves. 
S36/37/39:Wear suitable protective clothing, gloves and eye/face protection. 
S22:Do not breathe dust.
WGK Germany: 3
Hazard Note: Irritant
HazardClass: IRRITANT

 2,4-Difluorophenylhydrazine hydrochloride , its cas register number is 51523-79-6. It also can be called 1-(2,4-Difluorophenyl)hydrazine hydrochloride ; and (2,4-Difluorophenyl)hydrazine hydrochloride (1:1) .
 2,4-Difluorophenylhydrazine hydrochloride (CAS NO.51523-79-6) is hazardous, so the first aid measures and others should be known. Such as: When on the skin: first, should flush skin with plenty of water immediately for at least 15 minutes while removing contaminated clothing and shoes. Secondly, get medical aid. Or in the eyes: Flush eyes with plenty of water for at least 15 minutes, occasionally lifting the upper and lower eyelids. Then get medical aid soon. While, it's inhaled: Remove from exposure and move to fresh air immediately. Give artificial respiration while not breathing. When breathing is difficult, give oxygen. And as soon as to get medical aid. Then you have the ingesting of the product : Wash mouth out with water, and get medical aid immediately.
 2,4-Difluorophenylhydrazine hydrochloride (CAS NO.51523-79-6) could be stable under normal temperatures and pressures. It should avoid the condition like incompatible materials, light. It is not compatible with strong oxidizing agents. And also prevent it to broken down into hazardous decomposition products: hydrogen chloride, carbon monoxide, oxides of nitrogen, carbon dioxide, hydrogen fluoride gas. However, its hazardous polymerization has not been reported. In addition, It should be stored in a cool, dry place, or stored in a tightly closed container.