Why Do Some CDRs Smell Like Almonds?

bertok asks: "I have several spindles of CD-Rs of various brands that I use at home and work, and some of them have a very strong almond odour when opened. Does anyone know what causes that? I know that Hydrogen Cyanide has a distinctive almond odour, but so does a range of other organic chemicals. Can any Slashdot readers with a chemistry background enlighten us as to the possible source of the smell?"

Comments

benzaldehyde

[mpweasel]

IANAChemist, but the son of one, and my best guess is that it's benzaldehyde left over from the production of the plastic.

http://www.bartleby.com/65/be/benzalde.html
htt p://www.bartleby.com/65/al/aldehyde.html

Re:Cyanide is used

[portege00]

It's not CYANIDE, it's CYANINE. Here's some more information on that:

http://www.cdrplanet.com/dye-layer.html

I'm pretty sure its oderless, too.

There is no cyanide.

[TitaniumFox]

...and quit spreading misinformation.

Firstly, a cyano group is simply a carbon atom bonded to a nitrogen atom with a triple bond. In the term cyanide, the ide simply identifies the CN as an ion. Hydrogen cyanide (HCN) is the colorless, poisonous gas that may, or may not smell like almonds. (Go ahead...smell it.)

The blue dye you are thinking about is called cyanine, which is simply the common name for 1,1-diisoamyl-4,4-cyanine iodide.

If you go here, you will see a structure of cyanine. The only nitrogen present in the chemical is firmly rooted in a benzine ring (called pyridine). It's not going anywhere, and there's certainly no cyanide.

Additionally, the other dye used in CDRs is called phthalocyanine. Structure here. As you can see, the molecule is circular and the CN groups are in rings and in bonds between the ring structures. No hydrogen cyanide will be evolved.

While this doesn't answer why CDRs smell like almonds after/while they are being burned (do they? I've never smelled that), it does cast away some of the misperceptions.

Cyanide does not smell like almonds

[Muhammar]

You can smell HCN when you sniff at the bottle with cyanide or cyanoborohydride - it is a bitter, nasty, almnost pyridine-like stink. Sure, cyanide is in bitter almonds and peach inner seeds, it makes part of their flavour.

What you smell is the common almond-food flavor (Dr.Pepper flavor)- benzaldehyde, most likely. They add this stuff into some furniture polish, too.
The other possible, very similar almond-smelling substances are nitrobenzene (poisonous) and benzonitrile.

I think it is some kind of solvent/paint additive which they use for printing the label on the CD, definitely not anything essential for the CD manufacture.

[And, cyanin is a non volatile dye and has nothing to do with cyanide - the name is similar because of the greek word cyanos=blue]