Rectified, absolute or denatured
Ethanol (C₂H₅OH, CAS 64-17-5) is supplied in several distinct forms. The difference between them is water content and whether a denaturant has been added to make the material undrinkable.
| Grade | Concentration | Notes | Typical use |
|---|---|---|---|
| Rectified spirit | 95–96% | The natural fermentation azeotrope | General solvent, chemical feedstock, perfumery |
| Absolute (anhydrous) | ≥99.5% | Water removed beyond the azeotrope | Moisture-sensitive synthesis, fuel blending |
| Denatured (IMS) | 95–96% plus denaturant | Rendered undrinkable | Industrial solvent and cleaning |
| Pharmaceutical | 96% or ≥99.5% | BP / USP / EP monograph | API synthesis, GMP disinfection |
| Food (FCC) | 95–96% | Fermentation-derived, low fusel alcohols | Flavour extraction, food processing |
| Disinfectant | 70% in water | Pre-diluted | Surface disinfection |
Ethanol and water form an azeotrope at about 95.6%, which is why ordinary distillation stops there. Getting to absolute grade requires an extra dehydration step, and that step is what you pay for. If your process tolerates a little water, rectified spirit does the same job for less.
Key physical properties
| Property | Value |
|---|---|
| Chemical formula | C₂H₅OH |
| CAS number | 64-17-5 |
| Molecular weight | 46.07 g/mol |
| Boiling point | 78.4 °C |
| Flash point | 13 °C — highly flammable |
| Auto-ignition temperature | 365 °C |
| Density at 20 °C | 0.789 g/cm³ |
| Vapour pressure at 20 °C | 59 mmHg |
| Explosive limits in air | 3.3–19.0% v/v |
Why 70% outperforms 99% for disinfection
This is the most common and most expensive misunderstanding in ethanol procurement. Higher concentration does not mean better disinfection — it means worse.
| Concentration | Antimicrobial effect | Why |
|---|---|---|
| 50–60% | Moderate | Slower kill rate |
| 70–80% | Optimal | Water lets ethanol penetrate the cell before evaporating |
| 90–95% | Reduced | Evaporates before adequate contact time |
| 99.5% | Least effective | Instantly dehydrates the cell surface without penetrating |
If you are buying ethanol for surface disinfection, specify 70% and stop paying a premium for absolute grade that performs worse at the task. Buying 96% and diluting on site is often the cheapest route, provided the dilution is controlled and documented.
The methanol limit matters
Fermentation ethanol carries trace methanol and fusel alcohols. For industrial solvent use this is irrelevant. For pharmaceutical or food use it is the parameter the monograph exists to control.
| Parameter | BP limit |
|---|---|
| Ethanol content | 95.1–96.9% v/v, or ≥99.5% for absolute |
| Methanol | ≤50 ppm |
| Aldehydes (as acetaldehyde) | ≤10 ppm |
| Non-volatile matter | ≤2.5 mg/100 mL |
| Appearance | Colourless and clear |
Where it is used, and what that implies for grade
- Pharmaceutical manufacture — synthesis, tinctures and GMP surface disinfection, against BP, USP or EP grade
- Disinfection and sanitiser production — 70% is the working concentration regardless of what you buy
- Chemical feedstock — ethyl acetate, ethylamines and other derivatives
- Perfumery and personal care, where fusel alcohol content affects odour
- Food and flavour extraction, requiring FCC grade
- Industrial cleaning and printing, where denatured grade is normally the correct commercial choice
What to put on the RFQ
- Grade and concentration — "denatured, 96%" or "absolute, ≥99.5%", plus the monograph if pharmaceutical or food
- Denaturant type where it matters, since some denaturants interfere with downstream processes and some are unacceptable in cosmetics
- Methanol and aldehyde limits for regulated applications
- Quantity per delivery and annual volume
- Pack — drum, IBC or tanker — and whether returnable
- Delivery city and confirmation of compliant flammable storage
- Documentation, including any excise or regulatory paperwork your site needs to hold the material
What drives the price
- Molasses and sugarcane pricing, since Pakistani ethanol is largely fermentation-derived from molasses
- Export demand, which competes directly with domestic industrial buyers and can tighten local availability
- Grade — absolute costs more than rectified because of the extra dehydration step; pharmaceutical grade costs more again
- Denaturant type and whether the denatured formulation is a standard one
- Regulatory and excise treatment, which differs between denatured and undenatured material
- Pack format, freight and delivery city
Sourcing considerations in Pakistan
- Pakistan has a substantial molasses-based ethanol industry, so domestic supply is genuinely available rather than import-only — an unusual position among the chemicals in this range
- Undenatured ethanol is a controlled product; confirm what licensing or documentation your site needs before ordering, because this is where orders most often stall
- Denatured grade avoids much of that administrative burden and is the right default for industrial solvent and cleaning use
- Ethanol moves as a Class 3 flammable liquid, so transport and storage must be compliant