If you have ever wondered what gives certain petroleum products their distinctive yellow tint — or how refineries tell one fuel grade from another at a glance — there is a good chance Yellow 107 is part of the answer. Solvent Yellow 107 (CAS No. 67990-27-6) is a workhorse dye in the global petroleum industry, quietly doing its job in fuel tanks, lubricant drums, and wax processing lines around the world.
In this guide, we will walk through everything you need to know about Yellow 107 — from its chemical makeup and performance characteristics to its real-world applications and how it compares with other yellow solvent dyes. Whether you are a fuel blender, a procurement specialist, or someone researching dye options for an industrial project, this article has you covered.
What Exactly Is Yellow 107?
Yellow 107, officially designated C.I. Solvent Yellow 107 (Colour Index No. 21140), is a synthetic double-azo dye with the CAS number 67990-27-6. Its molecular formula is C₄₄H₅₈N₄O₂, and it has a molecular weight of 674.96 g/mol. The dye is manufactured by double diazotisation of 3,3′-dimethylbenzidine, followed by coupling with 4-nonylphenol.
In appearance, Yellow 107 produces a warm, reddish-yellow hue and is fully oil-soluble — meaning it dissolves in hydrocarbon-based solvents, petroleum products, and non-polar media without any cloudiness or residue. It is commercially available in liquid form, typically formulated in high-flash solvents, xylene or toluene solvent systems.
What makes Yellow 107 particularly useful is its combination of strong tinting strength, excellent solubility across a range of petroleum products, and good thermal stability. It does not affect the functional properties of the fuels or oils it colours, which is exactly what the industry demands.
Key Chemical Properties of Yellow 107 (CAS 67990-27-6)
Here is a quick-reference summary of the essential chemical and physical properties of Yellow 107:
| Property | Details |
| C.I. Name | Solvent Yellow 107 |
| C.I. Number | 21140 |
| CAS Number | 67990-27-6 |
| Chemical Class | Diazo (Double Azo) |
| Molecular Formula | C₄₄H₅₈N₄O₂ |
| Molecular Weight | 674.96 g/mol |
| Hue | Reddish Yellow |
| Solubility | Oil-soluble; fully miscible in petroleum products |
| Physical Form | Liquid (in solvent) |
| Common Solvents | High-flash (HF), Xylene (XY), Toluene |
| Recommended Dosage | 10–20 ppm |
| Shelf Life | 2 years (stored at 5–40°C in closed containers) |
| Synthesis | 3,3′-Dimethylbenzidine diazotisation + 4-nonylphenol coupling |
These characteristics make Yellow 107 a reliable choice for any application that needs a stable, vivid yellow colourant in a non-aqueous, hydrocarbon-based system.
Primary Applications of Yellow 107
1. Fuel and Petroleum Product Colour-Coding
The single biggest application for Yellow 107 is in the petroleum industry. Refineries and fuel distributors use it to colour-code different grades and types of fuel — distinguishing leaded from unleaded gasoline, high-octane from low-octane fuel, or different sulphur-level diesel grades. This colour differentiation is not just cosmetic; it is a critical safety and compliance measure that prevents dangerous mix-ups during storage, transportation, and dispensing.
Different countries mandate specific dye colours and concentrations for various fuel types. Yellow 107 is widely used across Asia, Africa, and the Middle East for these fuel identification programmes, and it is one of the key yellow dyes approved for petroleum colouring in India and several other markets.
2. Lubricants, Greases, and Industrial Oils
Manufacturers of transmission fluids, hydraulic oils, gear oils, and industrial lubricants use Yellow 107 to impart a consistent, recognisable colour to their products. This helps end-users identify the product type at a glance and also serves as a brand differentiator in a competitive market.
3. Wax, Candle, and Speciality Product Colouring
Yellow 107 dissolves cleanly in paraffin and other wax bases, making it a popular choice for candle and wax product manufacturers who need a bright, stable yellow. Its high solubility means no sediment, no clogging of wicks, and no uneven colour distribution.
4. Printing Inks and Coatings
In oil-based printing ink formulations, Yellow 107 provides strong tinting strength and fast dispersion, allowing for uniform colour output even at low concentrations.
Application Overview Table
| Application Sector | Specific Use | Why Yellow 107 Is Preferred |
| Fuel & Petroleum | Gasoline, diesel, kerosene, gas oil | Full miscibility, regulatory approval, consistent hue |
| Lubricants & Fluids | Transmission fluid, hydraulic oil, gear oil | No residue, stable colour, brand differentiation |
| Wax & Candles | Paraffin, soy, and gel wax colouring | Clean dissolution, bright finish, no wick clogging |
| Printing Inks | Oil-based ink formulations | Strong tinting strength, fast dispersion |
| Industrial Oils | Cutting oils, mineral oils, heat transfer oils | Thermal stability, inert at working temperatures |
Yellow 107 vs. Other Common Yellow Solvent Dyes
There are several yellow solvent dyes available on the market. How does Yellow 107 stack up? Here is a side-by-side comparison with three commonly encountered alternatives:
| Parameter | Yellow 107 | Yellow 124 | Yellow 14 | Yellow 56 |
| CAS Number | 67990-27-6 | 34432-92-3 | 842-07-9 | 2481-94-9 |
| Chemical Class | Double Azo | Azo | Mono Azo | Azo |
| Primary Use | Fuel/oil colour-coding | EU Euromarker (fiscal) | Wax, shoe polish, oils | Heating oil, fuel marking |
| Hue | Reddish yellow | Yellow (near-colourless at low ppm) | Orange-yellow | Yellow |
| Solubility in Fuel | Excellent | Good | Moderate | Good |
| Tinting Strength | High | Low (marker, not visual dye) | Moderate | Moderate |
| Dosage (Fuel) | 10–20 ppm | 6–9 mg/L (EU mandated) | Varies | Varies |
| Regulatory Role | Visual colour-coding | Fiscal marker (EU) | General industrial | General fuel dye |
The key takeaway: Yellow 107 is designed for strong visual colouring of petroleum products, whereas Yellow 124 serves as a near-invisible fiscal marker. They play entirely different roles and are often used alongside each other in fuel marking programmes.
Case Study: Standardising Fuel Colour-Coding for an Indian Petroleum Distributor
Background: A mid-size petroleum distributor operating across western India was facing recurring issues with fuel identification at their depot network. Different terminals were using dyes sourced from multiple local suppliers, leading to noticeable colour inconsistencies between batches of the same fuel grade. During a regulatory inspection, auditors flagged that the yellow tinting in their branded kerosene varied significantly across three depots — some batches appeared pale straw-coloured, while others were a deep amber.
The Problem: The inconsistency created confusion among depot workers and raised concerns about possible adulteration. The distributor needed a single, reliable yellow dye solution that would deliver uniform colour across all locations without requiring changes to their existing blending infrastructure.
The Solution: The distributor consolidated their yellow dye supply with a single ISO-certified manufacturer producing Yellow 107 (CAS 67990-27-6) in a high-flash solvent base. The new formulation was pre-calibrated for a standard dosage of 15 ppm, delivered in ready-to-use liquid form that could be injected directly into fuel lines without pre-dilution.
Results:
| Metric | Before (Multiple Suppliers) | After (Single Yellow 107 Source) |
| Colour Consistency (visual) | Significant variation across depots | Uniform across all 7 depots |
| Batch Rejection Rate | ~12% | <1% |
| Supplier Count | 4 different dye vendors | 1 ISO-certified manufacturer |
| Dosage Standardisation | Varied (8–25 ppm) | Fixed at 15 ppm |
| Annual Dye Cost | Baseline | ~14% reduction (volume pricing) |
| Regulatory Audit Flags | 2 in 12 months | 0 in 12 months |
Key Takeaway: Consolidating to a single, quality-assured Yellow 107 supply eliminated the batch-to-batch variation that had been causing compliance headaches. The experience underscores a principle that holds true across the petroleum dye industry: consistency of supply matters just as much as the chemical itself.
What to Look for When Sourcing Yellow 107
Because Yellow 107 is a commercial dye and not a single pure compound (the alkylation and coupling process produces a mixture of related structures), quality can vary significantly between manufacturers. Here are the factors that matter most:
Impurity-free formulation: The product should be completely free of insoluble particles. Even trace amounts of insoluble matter can accumulate in fuel injection systems and storage tanks over time.
Full miscibility: Yellow 107 must dissolve completely in the target fuel or oil product, producing a clear, homogeneous colour with no haziness or phase separation.
Batch-to-batch consistency: Look for manufacturers who perform spectrophotometric quality checks on every production batch to ensure consistent colour strength and hue.
Flexible solvent bases: Depending on your application, you may need Yellow 107 in a high-flash solvent, xylene, or toluene base. A capable manufacturer will offer all three options.
ISO certification: Manufacturers holding ISO 9001:2015, ISO 14001:2015, and ISO 45001:2018 certifications are demonstrating commitment to quality, environmental compliance, and safety.
Anar Chemicals LLP (anarchem.com) is an established manufacturer that ticks all of these boxes — ISO 9001:2015, ISO 14001:2015 & ISO 45001:2018 certified, with over four decades of experience in dyes and speciality chemicals. They produce Yellow 107 in high-flash, xylene, and toluene solvent bases and supply to petroleum companies across the globe. Explore their full Liquid Petroleum or Fuel Dyes product range for more details.
Frequently Asked Questions About Yellow 107
Q: What is Yellow 107 used for?
Yellow 107 (Solvent Yellow 107, CAS 67990-27-6) is primarily used for colouring and differentiating petroleum products such as fuels, lubricants, and industrial oils. It is also used in wax colouring, candle manufacturing, printing inks, and certain plastic formulations.
Q: What is the CAS number for Yellow 107?
The CAS number for Solvent Yellow 107 is 67990-27-6. Its Colour Index number is C.I. 21140.
Q: Is Yellow 107 the same as Solvent Yellow 124?
No. Yellow 107 (CAS 67990-27-6) and Solvent Yellow 124 (CAS 34432-92-3) are chemically different dyes with distinct structures and applications. Solvent Yellow 124 was used as the EU Euromarker for tax-exempt fuel identification, while Yellow 107 is primarily used for visual fuel colour-coding and industrial colouring. They serve complementary but separate roles.
Q: What is the typical dosage for Yellow 107 in fuel?
Yellow 107 is generally used at a dosage of 10 to 20 parts per million (ppm) in petroleum products, depending on the desired shade intensity and the specific product being coloured.
Q: Does Yellow 107 affect fuel performance or engine operation?
No. Solvent Yellow 107 is chemically inert in hydrocarbon systems at the concentrations used for colouring. It does not alter combustion characteristics, octane or cetane ratings, or the mechanical performance of engines.
Q: How should Yellow 107 be stored?
Yellow 107 should be stored in tightly closed containers, away from direct sunlight, at temperatures between 5°C and 40°C. Under these conditions, the product has a shelf life of approximately 2 years from the date of manufacture.
Q: Where can I buy high-quality Yellow 107?
Yellow 107 is available from speciality chemical manufacturers such as Anar Chemicals LLP (anarchem.com), an ISO-certified company with over four decades of experience in petroleum dyes and speciality chemicals. They produce Yellow 107 in high-flash, xylene, and toluene solvent bases.
Q: Is Yellow 107 safe to handle?
Like most industrial solvent dyes, Yellow 107 should be handled with standard precautions — protective gloves, eye protection, and adequate ventilation. Always consult the manufacturer’s Safety Data Sheet (SDS/MSDS) for product-specific safety information.