New answers tagged alcohols
3
My take as to the likely role for a catalytic amount of copper powder, $\ce{CaCl2, HCl},$ and $\ce{CuCl}$ is as follows:
$\ce{ Cu + Cu(II) <=> 2 Cu(I) }$
where the $\ce{Cl-}$ presence forms a soluble complex to keep the reaction reversible:
$\ce{ CuCl + Cl- <=> CuCl2- }$
The first equation is an example of a working so-called redox couple with ...
3
but here we are shifting the carbocation from secondary to primary
Firstly the shift is not from secondary to primary but from tertiary to secondary.
I was told that methyl shift is done to stabilise the carbocation
Yes, a methyl shift is done to stabilise a carbocation. And it is done in this case for the same reason, to increase the relative stability.
...
4
I found that the reaction you describe is a special form of the Schotten-Baumann reaction.
The special form of the reaction is called Einhorn-Acylierung ("Unicorn acylation" in English). It is named after the chemist Albert Einhorn (Einhrorn means "unicorn" in German and hence the reaction name).
The reaction mechanism is as follows:
...
5
A ring expansion typically occurs to overcome the high strain present in smaller sized rings.
Now strain isn't one single thing but a combination of many different factors which are nicely summarized by this[1] paper.
Types of strain
... the total strain of a conformation is the sum
of:
Bond strain—stretching or compression of chemical bonds. This type of ...
5
The mechanism for the given reaction would be as follows.
Why does this happen? This is because a four member ring has a high amount of ring strain. Expanding itself to a 5 member or (if possible) a six member ring is highly advantageous as it helps alleviate some of this ring strain.
Now, in this case there is also the added advantage of the six member ...
2
According to Advanced Organic Chemistry[1],
Neopentyl systems are typically resistant to nucleophilic substitution reactions. They are primary, so do not form stable carbonium ions, and the tert-butyl substituent effectively hinders back-side attack. [...] Under conditions that
favor ionization, rearrangement usually occurs, and the products are derived ...
2
TL;DR The Grignard reagent reacts via the SN2 mechanism and attacks the less sterically hindered carbon.
Now, this reaction is similar to the opening of an epoxide ring by a strong nucleophile, wherein the less sterically hindered position is favored for attack by the nucleophile.
According to SN2 type Reactions of Epoxides from Organic Chemistry, 5th ...
1
As @Shoubhik R Maiti said, Grignard reagent won't attack the second $\ce{C}$ as, being farther away from the electronegative atom $\ce{O}$, it has less partial polarity.
Now, Grignard being a strong nucleophile, would attack the carbon with highest partial positive charge, hence we are left with a $3°$ carbon and a $2°$ carbon adjacent to $\ce{O}$ where ...
1
Actually, in this case, a hydride shift from C4 seems more likely. Allylic carbocations tend to be more stable than even tertiary non-conjugated carbocations. Under SN1 circumstances you'd get a mixture of 5,5-dimethyl-3-chloro-1-hexene and 5,5-dimethyl-1-chloro-2-hexene. Under forcing conditions further addition might take place, mainly to the 1,3-...
0
The mechanism of dehydration of 2° alcohol at high temperature (around 170°C-180°C) happens via $E_1$ mechanism. This means that the major product will be decided by the $\mathbf {Zaitsev}$ $\mathbf{rule}$, which says that major product will be the stables one. If you compare the three alkenes, you'll see that the middle compound you've drawn has the most ...
2
Although this question is from textbook written by a professor in well established institute, it lacks completeness. For example, the question is written such a poor way that it even didn't give any conditions or even in which solvent the reaction has performed. So, it's safe to assume that the reaction has performed in thermodynamic control. We'll say it is ...
3
The reaction pathway I would propose for the obtained products is as below:
Coming to the percentage of each product obtained, I would defer from the data provided in the question. I would believe that V would be the major product because it is both thermodynamically and kinetically the best possible product.
I would be the next best as it is formed from ...
2
Azeotropic composition is a function of the boiling pressure and therefore of the boiling temperature. This can be seen in looking up the composition of the constant boiling $\ce{HCl}$ azeotrope with changing atmospheric pressure. However, information on this is hard to find and the effect seems to be small in most cases. Wikipedia does discuss this a bit. ...
3
The reaction of alcohol + NaOH producing $\ce{C2H5ONa}$ + water is an equilibrium which is usually strongly pushed to the left hand side. But in the presence of $\ce{CS2}$, the alkoxide $\ce{C2H5ONa}$ is transformed into xanthate. So the equilibrium is driven to the right hand side.
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Concentrated sulphuric acid is a highly acidic medium and thus it very exclusively prefers the $E_1$ mechanism over $E_2$ mechanism and thus a carbocation is surely formed in this conditions.
The example you provide proceeds through the following mechanism:
Now the mechanism you provide, other than following the wrong pathway(very minor pathway) also has a ...
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