2-Iodothiophene, known by its molecular formula C4H3IS, brings together the core structure of thiophene and the substantial presence of iodine at the 2-position. This yellowish crystalline solid, sometimes showing up as powder or even small flakes because of storage conditions, catches the eye for its clear, defined chemical signature. Looking up the CAS Number 697-97-0 gives a trail of research papers and supply listings, a signal that this compound has found active use in chemical industries for years.
Take a close look at its molecular structure. The sulfur ring — characteristic of thiophenes — remains unchanged, but once you attach iodine, things shift for both physical and chemical behavior. Its molecular weight sits at 241.04 g/mol, certainly heavier compared to unsubstituted thiophene or even bromo or chloro variants. At room temperature, 2-Iodothiophene holds a moderate melting point, falling around 31-33°C. It’s not a compound you store in high heat. The density, floating near 2.01 grams per cubic centimeter, makes it noticeably weightier than its close relatives; a scoop of this powder feels heavier than compounds with similar form. Solubility tends toward organic solvents — ether, dichloromethane, and chloroform work well — but you won’t see it dissolve in water.
Buyers often find 2-Iodothiophene supplied as a pale yellow to off-white solid, packed in glass bottles or sealed containers to avoid moisture contamination. Sometimes the market offers it as flakes, at others as fine powder or rare crystal grains, each form reflecting how well the batch was purified and how it traveled from factory to bench. Safe handling and minimal moisture contact matter most. Reactivity, especially from the iodine atom, can create complications if kept in poorly sealed packaging. Some suppliers offer 2-Iodothiophene measured in grams, others scale up by the liter as a solution in a volatile solvent for labs focusing on efficient transfer and dosing. In production, it’s used mainly as raw material, not as a final consumer product.
Safety information should always follow 2-Iodothiophene. Iodinated compounds come with clear hazard expectations. This chemical gives off fumes that can irritate eyes and respiratory tract. In my work, even a split pipette tip carrying a tiny amount can fill a fume hood with a noticeable chlorine-iodine tang after a few minutes. Spills and open containers ramp up exposure risk — gloves, lab coats, and goggles never feel like overkill. Skin or prolonged inhalation won’t just create discomfort; over time, there’s a risk of thyroid disruption typical of iodine-containing substances. Data sheets (SDS) catalog the relevant hazard pictograms: harmful if swallowed, irritant, possible damage to aquatic life. Once opened, store under inert gas, sealed, and away from sunlight. Regular users learn fast that a mislabeled or loosely capped bottle can compromise not just sample integrity but personal safety, too. Disposal routes track with halogenated solvents — trusted chemical waste containers, careful documentation, nothing poured down the drain.
Harmonized System Code (HS Code) classification supports both export and import compliance; for 2-Iodothiophene, 2934.99 usually fits. This number communicates to customs the chemical’s status as an organic compound, uncommon in the daily economy but necessary for global trade and regulatory checklists. Importers and shippers deal with dual paperwork: documentation of the raw material’s purity specifications, and separate safety reports for transit, especially as quantities scale up for pharmaceutical intermediates or specialty chemical batches. Experience proves that accurate labelling speeds custom clearance more than any negotiation letter ever could. Any slip can shut down a shipment, frustrating both buyer and seller.
Chemists, particularly in pharmaceuticals and advanced materials, turn to 2-Iodothiophene for one main reason: the iodine atom serves up a reactive handle. It’s the launchpad for cross-coupling reactions — Suzuki, Sonogashira, and Heck — steps every organic chemist learns to wield early on. Those engineered C–C bonds allow researchers to build more complex, active molecules, including biologically active small molecules and custom ligands. If someone wants to piece together a new drug candidate, a polymer incorporating aromatic sulfur, or a material with electrical properties tuned for sensors, chances are they’ll see 2-Iodothiophene on their reagent list. My own attempts at cross-coupling this compound with various boronic acids have shown the role packing and storage play: moisture reduces yield and purity, teaching a fast lesson in lab discipline.
The unique structure of 2-Iodothiophene, featuring both aromaticity and a heavy halogen, steers its physical properties in a way that gives researchers control over synthetic pathways. Unlike unsubstituted thiophene, the iodine substituent brings down electron density, opening up sites for further substitution and tuning the compound’s reactivity. Electronic properties shift, guiding chemists toward new products with specified optical or electrical characteristics. Purity affects color and melting behavior — even trace impurities can throw off measurements, introducing inconsistencies from batch to batch. Anyone who has used a poorly purified batch knows the pain of repeated column runs, struggling to get a white powder that still clings to yellow after each pass. Hydrolysis and oxidation both threaten shelf life, pushing users to fresh bottles for every big synthesis campaign, no matter how tempting it is to squeeze the costs. Product datasheets promise stability under inert gas, but in a real lab, vigilance trumps written guidelines.
Behind the technical talk, handling and using 2-Iodothiophene feels as much about habit and awareness as it does textbook knowledge. Reading through a list of properties — melting point, density, molecular formula — guides protocol, but safe practice and consistent results come down to methods built up over days and years of real use. From weighing out dense flakes on an analytical balance to wiping up a spill with proper gloves, the hands-on challenges speak just as loudly as the bullet points in product catalogs. Remembering hazard codes, respecting storage guidelines, and responding fast to signs of decomposition or contamination build a sense of respect for these raw materials that can’t be replaced by specs alone. Each bottle in storage acts as a quiet reminder: knowledge and care work together to keep work productive and safe.
