Fatty acids: Characteristics
How chain length and iodine value decide the job
What this tab covers The physical and chemical properties that set its grade, price and uses, with the commercial grades and the standards that define them.Buyers specify fatty acids by chain-length distribution, degree of unsaturation (iodine value), colour and purity. These decide whether an acid suits tyres, cosmetics, soaps or alkyds.
Properties that matter commercially
| Property | Value / specification | Why it matters | Source |
|---|---|---|---|
| Acid value | about 200-210 mg KOH/g for stearic; about 275-280 for lauric (indicative) | measures purity and molecular weight | indicative |
| Iodine value | below 1 for triple-pressed stearic; about 90 for oleic (indicative) | unsaturation affects colour stability and odour | indicative |
| Titre (solidification point) | about 54-56°C for stearic 50/50 grades (indicative) | processing and texture in candles and cosmetics | indicative |
| Colour | Lovibond or Gardner limits (indicative) | white cosmetics need low colour | indicative |
Commercial grades
- Triple-, double- and single-pressed stearic acid
- Lauric acid C12 98-99%
- Caprylic-capric C8-C10 (for MCT oils and esters)
- Oleic acid
- Distilled palm and coconut fatty acids
- Tall oil fatty acids (TOFA)
- Hydrogenated tallow fatty acid