5-chlorothiophene-3-carboxylic acid

Basic information

CAS number: 63136-58-1

Molecular formula: C₅H₃ClO₂S

Molecular weight: 162.59 (calculation method: C₅=60.05, H₃=3.02, Cl=35.45, O₂=32.00, S=32.07, the total is 60.05+3.02+35.45+32.00+32.07=162.59)

Structural features: The molecule is composed of a thiophene ring (a five-membered heterocyclic ring containing a sulfur atom), with a carboxyl group (-COOH) connected at the 3rd position of the thiophene ring and a chlorine atom (-Cl) at the 5th position. It is a thiophene derivative containing halogenated and carboxyl groups.

Physical and chemical properties

Appearance: Usually white to off-white crystalline powder (refer to the common form of similar thiophene carboxylic acid derivatives).

Melting point: There is no public accurate data, but it is estimated to be in the range of 150-180℃ (thiophene carboxylic acids with similar structures, such as 3-thiophene carboxylic acid, have a melting point of 136-138℃, and chlorination may increase the melting point).

Solubility: The carboxyl group (-COOH) is polar, and it is estimated to be soluble in alkaline aqueous solutions (such as sodium carbonate, sodium hydroxide solution), slightly soluble in water, easily soluble in polar organic solvents such as methanol, ethanol, and dimethylformamide (DMF), and difficult to dissolve in non-polar solvents (such as n-hexane, benzene).

Chemical properties: The carboxyl group has typical carboxylic acid properties and can undergo esterification reactions (esters with alcohols), amidation reactions (amides with amines), decarboxylation reactions, etc.; the chlorine atom on the thiophene ring can undergo nucleophilic substitution reactions under certain conditions (such as reactions with amines, sodium alcoholates, etc.).