[Cob] icynene and isocyanates

[Mary Hooper]

Will someone with expertise in chemisty  explain in everyday terms how we got from icynene to isocyanates -for those of us who flunked chemistry. 
I looked at the deerwod  site and saw nothing about icynene. It seems to me that starch and veggie compounds might not require toxic materials to create....but I don't, as you can tell, quite follow the thread here. 

thanks for being patient with me...Mary