Molecular Formula: C₈H₁₁ClN₂S
Molar mass: 202.7 g/mol
EINECS: 208-688-6
Flash Point: 125.1 °C
Boiling Point: 283.2 °C at 760 mmHg
Vapour Pressure: 0.0032 mmHg at 25°C 
Melting point: 172-177 °C
Water solubility: 250 g/L (15 ºC)
Sensitive: Hygroscopic
Appearance: Off-white to light beige crystalline powder
Product categories:  Sulphur Derivatives
Structure of Benzylisothiourea hydrochloride (538-28-3):

H-Bond Donor: 3
H-Bond Acceptor: 2
Systematic Name:Benzylsulfanylformamidine hydrochloride 
SMILES: Cl.S(C(=[N@H])N)Cc1ccccc1 
InChI: InChI=1/C8H10N2S.ClH/c9-8(10)11-6-7-4-2-1-3-5-7;/h1-5H,6H2,(H3,9,10);1H 
InChIKey: WJAASTDRAAMYNK-UHFFFAOYAY 
Std. InChI: InChI=1S/C8H10N2S.ClH/c9-8(10)11-6-7-4-2-1-3-5-7;/h1-5H,6H2,(H3,9,10);1H 
Std. InChIKey: WJAASTDRAAMYNK-UHFFFAOYSA-N

Reported in EPA TSCA Inventory.

Poison by ingestion, intraperitoneal, subcutaneous, and intravenous routes. When heated to decomposition it emits very toxic fumes of HCl, SO_x, and NO_x.
 

Hazard Codes: T
Risk Statements:
25:  Toxic if swallowed
Safety Statements:
28A     After contact with skin, wash immediately with plenty of water.
36:  Wear suitable protective clothing 
37:  Wear suitable gloves
39:  Wear eye/face protection
45:  In case of accident or if you feel unwell, seek medical advice immediately (show label where possible)

 Benzylisothiourea hydrochloride (538-28-3) also can be called Pseudourea, 2-benzyl-2-thio-, hydrochloride ; Pseudourea, 2-benzyl-2-thio-, monohydrochloride ; Carbamimidothioic Acid Phenylmethyl Ester Monohydrochloride ; S-Benzylthiouronium chloride ; S-Benzylthiopseudourea hydrochloride ;Pseudourea, 2-thio-2-benzyl-, hydrochloride ; S-Benzylthiuronium chloride ;and 2-Benzyl-2-thiopseudourea hydrochloride .It 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 immediatelyfor at least 15 minutes while removing contaminated clothing. Secondly,Get shoesmedical 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.
In addition, Benzylisothiourea hydrochloride (538-28-3) can be stable under normal temperature and pressure conditions.It is not compatible with strong oxidizing agents, and you must not take it with incompatible materials.And also prevent it to broken down into hazardous decomposition products: hydrogen chloride, nitrogen oxides, carbon monoxide, oxides of sulfur, carbon dioxide.