....Because I made the trans-trans 1,4-diphenyl -1,3 -butadiene with WIttig.
But I also get some impuritiy of the cis-trans isomer and some of the triphenyl phosphine oxide.
Using gascromatografy the main peak (trans-trans) arrives after 12.8min
But I also get two very small peak:
one at 11.5min
the other at 14min
I think the peak at 14min is the triphenyl phosphine oxide (more polar)
Don't know why the trans-trans has a higher B.P/ polarity than the cis-trans