[Sach]

In the attachment, you can find the direct arylation reaction that I performed.
In the following article, two mechanisms for direct arylation reaction are proposed:
http://pubs.acs.org/doi/abs/10.1021/ar3003305   (DOI: 10.1021/ar3003305)
One uses a carboxylic additive while the other one doesn't. I have performed the direct arylation reaction with pivalic acid as carboxylic additive. I was wondering if the direct arylation reaction would work equally good without the carboxylic additive (Figure2 in the article). Since there is no time left for me to actually try it in the lab, I was looking for answers in the literature.
In the following article I found that carboxylic additives facilitate reactivity and improve the yield (so it is recommended to use them during direct arylation reactions).
http://pubs.acs.org/doi/abs/10.1021/ma502131k    (DOI: 10.1021/ma502131k)
But this article is about poly(3-hexylthiophene). I was wondering if I can make the same conclusion about the molecule I am working with (protected thiophene).

Thnx in advance

[pgk]

Regardless a polymerization or not, the carboxylic acid and its nature play important roles in the reaction mechanism, as clearly stated in the cited reference. Thus, your reaction will probably not work well (if working at all) in the absence of acid.
But on the other hand, organic chemistry is an experimental science and therefore, safe conclusions without any doubt, can be made after verification by the experiment, only.

[Sach]

Yeah that's true.
Thanks

[Sach]

In the above mention article about carboxylic additives, the following is mentioned:
"As such, addition of certain carboxylic acids (acetic, pivalic, etc.) into the reaction mixture greatly facilitates reactivity and improves the reaction yield.1,2 This effect was studied in detail in the seminal work of Fagnou et al.,3−5 and it was attributed to the lowering of the activation barrier of the C−H abstraction step through
channeling the reaction into the so-called concerted metalation−deprotonation (CMD) pathway, which allows the
reaction to give products in high yields under relatively mild conditions"
So basically the carboxylic additive lowers the activation barrier and as a result, the reaction can proceed under mild conditions and give good yields. Or did I miss anything?

[pgk]

Furthermore, the longer the aliphatic chain of the carboxylic acid, the more effective the homogeneous catalysis is due to the increase of lipophilicity.
Besides, the reported “zigzag” behavior of cyclic secondary acids (depending on whether the acid contains an even or odd number of carbons) must be searched to steric reasons that promote or inhibit the “complete” contact with the reactants, depending on the "zigzag" flexible/strained conformation of such cyclic acids.