Indole CAS 120-72-9

Chemical Profile

Indole is a fused ring, a benzene ring joined to a pyrrole ring, that forms white flaky crystals melting at 51-54 °C. It occurs naturally in jasmine and neroli absolutes and in coal tar. The odor is the famous quirk: sharp and unpleasant neat, but floral and jasmine-like at the ppm levels used in perfumery. That double character is why the same chemical shows up in fine fragrance and in industrial synthesis.

Applications by Sector

• Pharmaceutical intermediates. The indole ring sits behind tryptophan, indomethacin, melatonin and serotonin-route actives; 99.0% HPLC batches feed the early synthesis steps ahead of GMP stages.
• Agrochemicals and plant growth. Starting material for indole-3-acetic acid (IAA) and indole-3-butyric acid (IBA) rooting and growth regulators, plus selected insecticide intermediates.
• Fragrance and flavour. Heavily diluted, it adds depth to jasmine, neroli and lilac bases and rounds out coffee, chocolate, nut and strawberry flavour notes (FEMA 2593); dosing runs at ppm level because neat material is overpowering.
• Dyes and specialty synthesis. Building block for indoline and indigoid dyes, pigments and functional heterocyclic molecules that need a fused nitrogen ring.
• Research and custom synthesis. 1 kg foil-bag lots support labs, pilot runs and custom-synthesis houses scaling a route toward drum volumes.

Quality Parameters

Freshness, Light and Summer Shipping

• Indole oxidizes on exposure to air and light, moving from white flakes through pale yellow to amber. Order fresh stock and check color and assay on arrival. UATChem ships recent-batch material only.
• Melting range 51-54 °C means drums inside a summer container can melt and re-solidify into blocks; assay is unchanged, but cool storage and shaded containers preserve the crystal form.
• Foil-bag and fibre-drum packs are sealed against moisture and light; nitrogen packing is available for pharma-intermediate lots on request.
• Store cool, dark, sealed and away from strong oxidizers. COA with HPLC trace, SDS and origin documents on every shipment; samples available; quotes within one working day. State the quantity and pack size in your RFQ.

FAQ

Q: Why does indole smell unpleasant but is used in perfume?

A: Neat indole is sharp; at ppm dilution it reads as jasmine, the effect used in perfumery.

Q: What purity is supplied?

A: 99.0% min by HPLC, melting range 51-54 C, with loss on drying capped at 0.5%.

Q: Will indole melt in summer shipping?

A: It melts at 51-54 C; it may re-solidify in the drum with no change in assay.

Q: What are indole’s main downstream uses?

A: Pharma intermediates, IAA/IBA plant growth regulators, jasmine fragrance and dyes.

Q: Why does stored indole turn yellow?

A: Air and light oxidize the surface; sealed, dark storage and fresh batches prevent it.