1. Education
You can opt-out at any time. Please refer to our privacy policy for contact information.

Discuss in my forum

Every chemical is assigned a CAS number. Have you ever wondered what a CAS number is and how they are assigned?

The Chemical Abstract Service or CAS

The Chemical Abstract Service is part of the American Chemical Society and maintains a database of chemical compounds and sequences. The CAS database currently contains over 55 million different organic and inorganic chemical compounds. Each CAS entry is identified by their CAS Registry Number, or CAS Number for short.

CAS Numbers

CAS Numbers are up to 10 digits long using the format xxxxxxx-yy-z. They are assigned to a compound as the CAS registers a new compound. The number has no significance to the chemistry, structure or chemical nature of the molecule.

The CAS Number of a compound is a useful way to identify a chemical over its name. For example, the compound CAS 64-17-5 refers to ethanol. Ethanol is also known as ethyl alcohol, ethyl hydrate, absolute alcohol, grain alcohol, hydroxyethane. The CAS number is the same for all these names.

The CAS Number can also be used to distinguish between stereoisomers of a compound. Glucose is a sugar molecule that has two forms: D-glucose and L-glucose. D-glucose is also called dextrose and has CAS number 50-99-7. L-glucose is the mirror image of D-glucose and has a CAS Number of 921-60-8.

What Is the IUPAC? | Chemical Common Names


November 9, 2010 at 7:59 pm
(1) Tony Machosky says:

Thanks for writing about CAS. Just wanted to mention that our full name is actually “Chemical Abstracts Service” and that “CAS RN” is our preferred short form for CAS Registry Number, which is also a registered trademark. Again, we appreciate your covering our subject material.

February 17, 2011 at 5:38 am
(2) RAM says:

good ..thanks for info

January 25, 2012 at 1:08 am
(3) aditya says:

gd work,thnkx

March 20, 2012 at 2:07 am
(4) bhupendra says:

What is CAS no. for filler masterbatch, is it no. of RM we have used for it.

Pls. reply

April 29, 2012 at 3:30 am
(5) zarad says:


May 17, 2012 at 12:53 am
(6) Sonia S says:

Nice article.

I would like to know why are two CAS numbers assigned to a unique chemical substance for example in the case of Propylene Glycol Dicaprylate/Dicaprate, this substance has two CAS nos. ie-68583-51-7 & 58748-27-9? Why is it so? CAS No is a unique number assigned to a specific substance right..

May 20, 2012 at 1:58 am
(7) margaret says:

Hi, i am interested to know how to register our products/ company for CAS Number :- and how long will take to procee, is it free or we to paid?

2. Are we able to use our supply CAS Number for our products if we are useing for our products?

August 29, 2012 at 2:37 am
(8) michelle says:

If CAS number is same for different INCI name, can I regard those as the same material?

August 29, 2012 at 11:47 am
(9) zohreh says:

hi. thanks for your good informations.i have qustion. do it may one cas number belong to two forms of a material?? Other words i bought liquid bisphenol a with cas 239658 , later i povided another solid one with same cas number??
Is this possible? Please guide me.

December 3, 2012 at 4:56 am
(10) chirag says:

i have observed the dobutamine hydrochloride has two CAS no. can anyone tell me y ? and which one is correct one

December 11, 2012 at 12:41 am
(11) saroop says:

Can a IUPAC name be generated from CAS number?

January 4, 2013 at 1:28 am
(12) Tushar Luhade says:

Thanx to dear mam

January 28, 2013 at 1:30 am
(13) Dimitris Hantzaras says:

Thank you for the article.

As I am not a chemist, I would like to ask if there possible to have Cas Numbers in the formt of yy-z (no x) or x-yy-z (only one x)

Many thanks in advance

Dimitris Hantzaras

January 28, 2013 at 7:00 am
(14) Gouav says:

Thanks a lot its really a good site……………

January 29, 2013 at 9:26 am
(15) soman says:


June 8, 2013 at 2:36 pm
(16) BADAR ALI says:


August 7, 2013 at 8:40 am
(17) krystal says:

Is a CAS number the same as a MSDS #?

November 6, 2013 at 2:41 am
(18) sherif says:

thank you very much

November 8, 2013 at 10:41 am
(19) silver says:

thanx 4da ans bt 2short ! may u explain mr?

November 9, 2013 at 1:01 am
(20) Rakesh Raina says:

In the first line you have said CAS No. is given to compounds. But actually we see it is given to all elements as well. Is that right ?

November 24, 2013 at 10:16 pm
(21) Ashraful Alam says:

Thanks for you information

December 11, 2013 at 1:54 am
(22) OMID says:

very very tanks

December 23, 2013 at 4:42 am
(23) ganesh.M says:

How to get CAS number…we are polymer compounder.
need to get CAS No.can you suggest and what is fee.

February 28, 2014 at 7:18 am
(24) Shabbir Shehaby says:

Need CAS numbers and monomer numbers here in Mumbai, India…. Can u help

March 6, 2014 at 12:04 am
(25) mohammad ali says:

Hi. Thanks a lot for your helpful information..

April 4, 2014 at 12:42 pm
(26) mehdi dasht bozorg says:

thanks for your useful and helpful information.

Leave a Comment

Line and paragraph breaks are automatic. Some HTML allowed: <a href="" title="">, <b>, <i>, <strike>
Top Related Searches
  • cas number
  • gp
  • ©2014 About.com. All rights reserved.