# CAS numbers for salts of molecules

Often times Pharma molecules come as different salts where the Cation changes. Do these have typically the same or different CAS numbers?

e.g. Take Glucosamine Hydrochloride. https://en.wikipedia.org/wiki/Glucosamine

It is available as as both the Na and K salt. But I cannot seem to find if they all have different CAS numbers.

What I have now is: 3416-24-8

Further complication seems that there is a Glucosamine Hydrochloride as well as a Sulfate. The wikipedia page describes both but I cannot see different CAS numbers. The sulfate itself seems available as either a Sodium or Potassium salt.

Any thoughts?

• They are different compounds; why would they have the same CAS number? – Ivan Neretin May 19 '18 at 7:03
• @IvanNeretin: Makes sense! – curious_cat May 22 '18 at 8:45

Every different compound has a different CAS number, even if they are enanthiomers when isolated and published (their racemic mixture has another CAS number). No exception! See following examples:

L-(−)-Glyceraldehyde: CAS Number [497-09-6].

D-(+)-Glyceraldehyde: CAS Number [453-17-8].

DL-(+/-)-Glyceraldehyde: CAS Number [56-82-6].

For your question, I found the CAS Number of D-(+)-glucosamine hydrochloride, which is [66-84-2]. The CAS Number [3416-24-8] is for glucosamine (free base).

The CAS Number of D-glucosamine sulfate is [14999-43-0]. Each molecule contains two molecules of glucosamines and one molecule of $\ce{H2SO4}$, the two acedic hydrogens on each of amine groups. Its molecular formula is $\ce{[C6H14NO5]2.SO4}$, giving the formula weight: $\pu{456.42 g/mol}$.

The CAS Number of D-glucosamine sulfate potassium chloride is [216699-44-4]. Each molecule contains two molecules of glucosamines, one molecule of $\ce{H2SO4}$, and two molecules of $\ce{KCl}$. Its molecular formula is $\ce{[C6H14NO5]2.SO4.2KCl}$, giving the formula weight: $\pu{605.52 g/mol}$. However, NIH website listed [1296149-08-0] as the CAS Number of glucosamine sulfate Potassium chloride, which must be issued a fairly recent time. Spectrum Chemical Co. sells the compound as a dietary supplement under the same CAS number.