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HLB factor - cetyl alcohol
Why cetyl alcohol has HLB value 15.5 but is not hydrophilic? How we calculate this value (15.5)?
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6 Replies
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What exactly are you trying to calculate?
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Hi! I am trying to understand why the hlb factor for cetyl alcohol is too high (15.5) although this molecule is lipophilic? There must be a formula to calculate this 15.5 value…
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I was curious too when started formulating. I thought everything above 10 is water soluble. Being fatty alcohols both cetyl and cetearyl alcohol aren’t soluble in water (the internet says they partially soluble in hot water but I think it’s an urban myth). The thing holding them from water solubility is long carbon tail. Saturated carbon chains are non-polar and as water is polar, so these two aren’t water soluble. That’s my understanding.
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Thats my understanding too, you are 100 % percent correct my friend! But what about HLB, 15.5 means that the 77.5 % of the molecule is hydrophilic…it doesn’t make sense.
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Cetyl alcohol is not an emulsifier. While it does have an OH group which can make it compatible with polar molecules, this is not enough to make it water soluble. Since it has no water solubility, it is not an emulsifier & the HLB value is a required HLB to get it to emulsify in the system. However, it is a co-emulsifier because when it is in an emulsions, its tails align with the oil groups and the OH aligns with water.
The equation to calculate HLB only applies to emulsifiers.
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You are so wright! Thank you!!
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