[craken66]

Hello,
I am writing to inquire reaction rate b/w speier's and karstedt's catalyst for hydrosilylation which is for coupling of Si-H and vinyl group. Which catalyst is better in terms of rxn rate? I'll appreiciated for anwering of it. Thank you.

[wildfyr]

Hmm... I frankly never noticed a big difference in speed, reactions were done in around 8 hours. However karsteadt's is more stable and less hygroscopic. Something important which BLEW MY MIND is that hydrosilation needs OXYGEN to work.

http://pubs.acs.org/doi/abs/10.1021/ja9825377

"The oxygen effect was first noted by Chalk and Harrod who reported that triethoxysilane and 1-alkenes did not react in the absence of air but reacted vigorously upon exposure to air using chloroplatinic acid as the catalyst."

[Enthalpy]

Wiki claims that the addition is most often anti-Markovnikov
https://en.wikipedia.org/wiki/Hydrosilylation
Did I read properly? How easy is it to obtain the anti-Markovnikov product?

And by the way, what do you think of wiki's reaction
Et₃SiH + PhC≡CPh  Et₃Si(Ph)C=CH(Ph)
I had expected Et₃SiC(Ph)=CH(Ph)

[wildfyr]

It is something like 99%+ anti markovnikov under typical conditions. I have never seen a markovnikov product in the NMR of my reactions.

I'm confused by your example, could you draw the lewis stuctures? My brain is telling me those are the same thing... is it E vs Z?

[Enthalpy]

Thank you!

About the example at Wiki, maybe I interpret it wrongly, like this:
Et₃Si(Ph)C=CH(Ph) here Ph is on Si, which is impossible with tetravalent Si
Et₃SiC(Ph)=CH(Ph) here Ph is on C, the product I expect after Si-H adds on C≡C

What is the convention? (Branches) written always after the carrying atom, like in Smiles, would be unambiguous but bring here the drawback of separating the C from the =.

[wildfyr]

Now that I know what you're getting at, I agree with your notation but this is one of those I might give a shot at IUPAC naming for more clarity