New answers tagged stability
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An acid catalysed dehydration reaction of alcohols will always proceed with the removal of -OH as H2O molecule and therefore, will be dependent on the formed carbocation's stability because the rate deternining step for this process is formation of carbocation. Carbocation Carbocation can be stabilized by inductive effect, field effect, mesomeric effect (or) ...
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Your basic assumptions are correct.
It can be observed as such:
In Q the carbocation is stablised by resonance, inductive and hyperconjugative effects so it is quite stable and will be formed fastest.
Comparing P and R: In P, a secondary carbocation is formed and there are 4+1 or 5 hyperconjugative structures possible. Moreover, the inductive effect is also ...
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I think the third option as greatest number of resonance structures can be alluded to it.
The following may suffice:
In the first one, the carbocation is isolated except for the presence of a single double bond in conjugation beside it. The oxygen and the double bond beside it play no role in stablizing it.
In the second one the lone pair on oxygen, the ...
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Your answer is the correct one. Acid-catalysed hydrolysis of epoxides proceeds exactly as shown. In the specific case of styrene oxide, nucleophiles attach themselves to the benzylic carbon1,2, which means that A should be the major product. I'm attaching an image from (1) which gives the products of reaction of methanol with styrene oxide:
If you want to, ...
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The other answer by permeakra is sufficient and complete. But, I'd like to add an explanation on how
"A carbonyl group normally destabilizes carbocations but stabilizes carbanions"
For instance, someone can think that the carbocation would resonate with the carbonyl group as what we've learnt earlier, I'd also thought in that way, initially. But, ...
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A carbonyl group normally destabilizes carbocations but stabilizes carbanions.
In this particular case, the rate of dehydration isn't guarded by carbocation stability, but by CH- acidity. In acidic conditions, OH group in alcohols is relatively easily protonated. Then, if there is a relatively acidic hydrogen in $\beta$-position it immediately dissociates, ...
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For this question, given the lack of initial information, I'm making the following assumptions:
Butane-2,3-diol dehydrates to give butan-2-one
2-butanol dehydrates to give but-2-ene
Butane-2,3-diol dehydration is nicely described in this paper from Emerson1:
Aqueous 2,3-butanediol was shown to react in a pseudo-first-order reaction in the presence of ...
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In the given problem, we have three compounds and have been asked to compare their heat of hydrogenation.
Starting Premise
We start from the fact that the heat of hydrogenation of a compound is inversely proportional to the stability of the double bond in the system. Using this we can say that the opposite of the order of stability would be the answer
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Following is an image of hyperconjugative effect. We can see a $\ce{\sigma}$-orbital delocalising electron pair with an empty $\ce{\pi^\ast}$-orbital.
The explanation to your problem can be given by deciding whether the effect is "centralized" or "decentralized". Let me explain it by an example.
A quick scene:
Suppose, you and your ...
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As already noted the thermal decomposition s commence at $\pu{300 °C}$ and includes $\ce{CO2 , SO2F2 , SOF2 , SOF4 , SO2}$ and possibly $\ce{H2S}$.
Not mentioned relating to its stability per an Atomistry reference is:
Mixed with hydrogen it withstands a high temperature, but under the influence of powerful electric sparks formation of hydrogen sulphide and ...
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From an IEEE paper1:
$\ce{SF6}$ begins to decompose at $\pu{300 °C}$ and the main decomposition components contain $\ce{CO2 , SO2F2 , SOF2 , SOF4 , SO2}$ and $\ce{H2S}$; [...] $\ce{H2S}$ is the special component only appears when thermal fault proceeds to some degree (above $\pu{360°C}$).
For more information about the decomposition mechanism and product ...
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