Thiophenes, a class of heterocyclic aromatic compounds containing a sulfur atom within a five-membered ring, form the backbone of numerous functional molecules with applications spanning pharmaceuticals, materials science, and agrochemicals. Among the diverse family of thiophene derivatives, 4-Bromothiophene-3-carbaldehyde (CAS: 18791-78-1) stands out due to its specific structural features and versatile reactivity, making it a subject of great interest in organic chemistry research. This article explores the fundamental chemistry of thiophenes, with a spotlight on this particular derivative.

The thiophene ring itself possesses aromatic character, influenced by the lone pair electrons of the sulfur atom. This aromaticity dictates much of its reactivity, often showing similarities to benzene but with enhanced reactivity, especially towards electrophilic substitution. The positions on the thiophene ring are numbered starting from sulfur as position 1, with positions 2 and 5 being more reactive than positions 3 and 4 in electrophilic aromatic substitution. However, substituents can significantly alter this inherent reactivity.

In the case of 4-Bromothiophene-3-carbaldehyde, the presence of both a bromine atom at the C4 position and an aldehyde group at the C3 position creates a unique electronic environment. The bromine atom, being an electron-withdrawing group via induction but electron-donating via resonance, influences the electron density distribution. The aldehyde group is a strong electron-withdrawing group, activating the adjacent positions towards certain reactions and deactivating the ring towards others. This combination makes the molecule particularly useful for specific synthetic transformations.

The synthesis of 4-Bromothiophene-3-carbaldehyde is often achieved through methods that carefully control regioselectivity. Direct bromination of thiophene-3-carbaldehyde can lead to mixtures of products. More precise routes involve halogen-metal exchange reactions, where precursors like 3,4-dibromothiophene are treated with strong bases (e.g., n-butyllithium) at low temperatures, followed by quenching with DMF to introduce the aldehyde group. This method is commonly employed by chemical manufacturers to produce the compound with high purity, typically exceeding 97%, a critical factor for researchers looking to buy this chemical.

The reactivity of 4-Bromothiophene-3-carbaldehyde is a key aspect of its utility. The aldehyde group readily undergoes nucleophilic addition, Wittig reactions, and condensations. The C-Br bond is an excellent handle for palladium-catalyzed cross-coupling reactions (e.g., Suzuki, Stille, Sonogashira couplings), allowing for the introduction of various carbon-based substituents. This dual reactivity enables chemists to synthesize complex molecules, including advanced materials for electronics and specialized intermediates for drug discovery. For example, it has been used in the preparation of NIR-absorbing polymers and as a precursor for various biologically active heterocycles.

For researchers in academic institutions and industrial R&D departments, accessing reliable sources of specialty chemicals like 4-Bromothiophene-3-carbaldehyde is fundamental. Understanding the CAS number 18791-78-1 is crucial when searching for this compound. Engaging with established suppliers, many of whom are based in China and offer competitive prices, ensures access to high-quality reagents that can accelerate research and development projects.

In essence, the study of thiophene chemistry, exemplified by compounds like 4-Bromothiophene-3-carbaldehyde, continues to unlock new possibilities in molecular design and application. Its specific chemical attributes make it a valuable intermediate for a wide range of advanced synthetic endeavors.