I would like to produce fatty acid cellulose esters (FACEs) using acyl chloride and pyridine. But, I do not understand what does 4 equivalents to cellulose anhydroglucose unit (AGU) means. This does affect my calculation in producing fatty acid cellulose ester. From what I understand 1 AGU unit consists of 3 hydroxyl groups which can form 3 ester unit.
Thank you for your time.
Hi Zhi Zhou Siew !
I understand you should add 4 equiv. for every OH group, you want to acylate. So, if you want to form an ester in all three OHs, you will end up adding 12 equiv. of acyl chloride. Guess too many equiv. are need since you are working with an oligo/poly-mer.
Good luck!
Hi Zhi Zhou Siew,
I understand it this way: you have four OH groups per monomer unit of glucose and therefore you use four mol acetyl chloride / pyridine, i.e. equimolar to the OH groups. I cannot say whether an excess of acid chloride / pyridine is necessary, cheap or unfavorable.
Keep on cooking!
Hi Leonardo González Ceballos and Andreas Pingel Keuth !
Does it means I have to add 4 mL of pyridine for every 1 g cellulose?
Well it´s more complicated than that. You need to know how many OHs (mmol) there are for gram of cellulose. If you want to acylate all of them, you have to multiply it by 4 and then, multiply by the MW and divide by the density of both pyridine and the acylating agent.
Oups, my mistake! There are three OH groups per glucose unit in cellulose; the way you wrote it, not four. You shouldn't rely on your memory ;-) The molar mass of a monomer unit (based on glucose, not cellobiose) is ~160 g / mol. So you have about 18.5 mmol of OH groups per g of cellulose. Therefore you need 1.45 g acetyl chloride and 1.46 g pyridine per g cellulose if you work equimolar. If you want or have to work in excess, correspondingly more.
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