High brow graffiti

It's been a long time since I took organic chemistry. I don't know what the message is here, but this is not the sort of graffiti you see every day.

[Laura]

It is unusual.

[Lin]

Nicely spotted and captured.

[Casablanca]

A bored organic chemistry student woz 'ere!

[Wendy]

Not sure what it would be - but someone was solving a problem and ran out of chalk for his blackboard!