Product Number: B007116
English Name: Brexpiprazole Impurity 116
English Alias: 1-(benzo[b]thiophen-4-yl)piperazine
CAS Number: 846038-18-4
Molecular Formula: C₁₂H₁₄N₂S
Molecular Weight: 218.32
As an impurity of Brexpiprazole, this compound has the following advantages:
Well-defined with distinct functional groups: Contains benzo[b]thiophene and piperazine rings. Unlike brexpiprazole (antipsychotic with piperazine-linked indolinone), its thiophene aromaticity and piperazine basicity create unique properties, enabling precise differentiation via HPLC/GC as a specific marker;
High stability and traceability: Rigid benzothiophene/piperazine structures and sulfur stability ensure neutral-to-weakly-alkaline stability. As a byproduct from incomplete piperazine-benzothiophene coupling, it directly reflects cyclization efficiency, improving process tracing accuracy;
High detection sensitivity: Benzothiophene conjugation shows strong UV absorption (230-260nm), combined with m/z 219 [M+H]⁺ enabling ppb-level analysis via LC-MS/GC-MS, compatible with antipsychotic heterocyclic impurity systems.
Pharmaceutical quality control: Used as an impurity reference standard to quantify Brexpiprazole Impurity 116 in APIs, ensuring residual coupling byproducts meet quality standards;
Synthesis optimization: Optimizing cyclization conditions (catalyst dosage) by monitoring impurity levels to reduce unreacted intermediates;
Intermediate purity assessment: Evaluating purity of key benzothiophene-piperazine intermediates in brexpiprazole synthesis to support indolinone coupling.
Brexpiprazole’s structure relies on a piperazine-linked benzothiophene-indolinone core, synthesized via piperazine-benzothiophene coupling. Incomplete coupling may generate benzothiophene-piperazine derivatives like Brexpiprazole Impurity 116. With shared ring systems affecting receptor binding, its residues risk reducing purity, making control critical for quality assurance.
Current research focuses on:
Analytical method validation: Developing HPLC assays with C18 columns for separation, achieving 0.1 ppb detection limits;
Coupling kinetics: Studying impurity formation under varying halide concentrations to clarify cyclization-impurity correlation;
Process refinement: Controlling impurity levels below 0.1% via solvent/catalyst optimization to enhance API purity;
Structural confirmation: Using ¹H/¹³C-NMR to verify benzothiophene-piperazine linkage, distinguishing from brexpiprazole for authoritative identification.
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