The compounds of formula according to the invention having a free carboxylic radical or a free amino radical may be converted in usual manner into their pharmaceutically acceptable salts. E.g. the compound of formula  is dissolved in its free form in a solvent, e.g. an alcohol or WATER, an adequate amount of hydrochlorid acid or Sodium hydroxide is added to the solution, the mixture is agitated at room temperature for an adequate period, then the solvent is distilled off, the residue is recrystallized and the salt of the compound of formula is obtained. Suitable examples for such pharmaceutically acceptable salts additionally to the salt of hydrochloric acid are the salts of SULFURIC ACID, nitric acid, phosphoric acid, sulfonic acid, benzoic acid, SUCCINIC ACID, Tartaric acid and citric acid. Examples for pharmaceutically acceptable addition salts of bases additionally to the sodium salt are the POTASSIUM salt, the calcium salt and the MAGNESIUM salt.
 

5-Chloro-2-thiophenecarboxylic acid, with the CAS Registry Number 24065-33-6, has the Molecular Formula of C₅H₃ClO₂S and Molecular weight of 162.594.  It is also called 2-Thiophenecarboxylic acid, 5-chloro-; 5-CHLORO-THIOPHENE-2-CARBOXILIC ACID.

Physical properties about 5-Chloro-2-thiophenecarboxylic acid are: (1)ACD/LogP: 2.87; (2)ACD/LogD (pH 5.5): 0.73; (3)ACD/LogD (pH 7.4): -0.23; (4)ACD/BCF (pH 5.5): 1.00; (5)ACD/BCF (pH 7.4): 1.00; (6)ACD/KOC (pH 5.5): 6.29; (7)ACD/KOC (pH 7.4): 1.00; (8)#H bond acceptors: 2; (9)#H bond donors: 1; (10)#Freely Rotating Bonds: 1; (11)Index of Refraction: 1.623; (12)Molar Refractivity: 36.462 cm³; (13)Molar Volume: 103.393 cm³; (14)Polarizability: 14.455 10-24cm³; (15)Surface Tension: 60.5610008239746 dyne/cm; (16)Density: 1.573 g/cm³; (17)Flash Point: 127.364 °C; (18)Enthalpy of Vaporization: 55.568 kJ/mol; (19)Boiling Point: 286.984 °C at 760 mmHg; (20)Vapour Pressure: 0.00100000004749745 mmHg at 25°C

When you are using this chemical, please be cautious about it as the following:
1. In case of contact with eyes, rinse immediately with plenty of water and seek medical advice;
2. Wear suitable protective clothing;
3. Wear suitable gloves and eye/face protection;

You can still convert the following datas into molecular structure:
(1)InChI=1S/C5H3ClO2S/c6-4-2-1-3(9-4)5(7)8/h1-2H,(H,7,8);
(2)InChIKey=QZLSBOVWPHXCLT-UHFFFAOYSA-N;
(3)Smilesc1(sc(Cl)cc1)C(=O)O

The toxicity data is as follows:

Organism	Test Type	Route	Reported Dose (Normalized Dose)	Effect	Source
mouse	LD50	intravenous	180mg/kg (180mg/kg)		U.S. Army Armament Research & Development Command, Chemical Systems Laboratory, NIOSH Exchange Chemicals. Vol. NX#03275,