Hi to every one,

I'm performing Wittig reaction using methyltriphenyphosphonium iodide (new), nBuLi in hexane (new) and my aldehyde, in dry THF (not totally fresh). I noted some colour change during the reaction. Time 0: suspension of phosphonium in dry THF (at rt, from white to lemon yellow after 10 min)

Time 1: the flask was cooled to 0 ° C (yellow)

Time 2: during the dropwise addition of nBuLi at 0 °: from yellow to white (I expected to get orange, or that it would remain yellow).

I tried several times and I always obtained these results.

Once, during the aldehyde addition (dropwise, at 0 ° C solubilized in dry THF), the colour suspension switched from withe to orange.

In any case, I never saw my desired product.

Please, what is your opinion about my problem?

Thanks in advance