It´s available at Sigma Aldrich and Acros. Check it on www.emolecules.com

It should be available at MERCK

you can by it from aldrich 1 mL = 78 Euro or you can post an enquiry on these companies from China http://www.lookchem.com/cas-453/4538-37-8.html

good luck

Thanks for feedback

... or you can prepare it as EtOAc solution in a test-tube by action of di- or triphosgene on butane-1,4-diamine under a short warming.

My response might be a little out dated for scientists who found their supplier for 1,4-butane diisocyanate but it probably will be highly valuable for anyone still searching for high quality butane diisocyanate (BDI). I just graduated BME and currently work for a supplier who is focussed on the stimulation of research with BDI for human health applications. Currently they are investing in upscaling their production and approving it for human health applications. If you are interested:

https://actu-all.com/product/14-diisocyanatobutane-cas-4538-37-8/

(>99.7% purity)

prices are very attractive

https://actu-all.com/product/14-diisocyanatobutane-cas-4538-37-8/