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3 answers
Why are pi bonds only formed when sigma bonds are formed?
While studying about bonding there was one statement that "pi bonds can only be formed only with sigma bonds" as we know that in double bond there is 1 sigma bond and 1 pi bond but then one question arises: Why is a pi bond formed only when a sigma…
Shashank
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19
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Reaction of perchloric acid with cyclopropenol
Question:
Identify A and B.
My attempt
The first step will be the attack of $\ce{PhMgX}$ on carbonyl carbon, that is, 1,2 position followed by hydrolysis, yielding an alcohol.
But how does the reaction proceed with $\ce{HClO4}$?
miyagi_do
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19
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1 answer
Why does benzene bend in this reaction?
From here
I can see why hapticity changes here, but not why it is necessary for the benzene ring to bend. The resonance energy of benzene is pretty large, and there's no balancing increase in stability elsewhere--unless the decrease of hapticity…
ManishEarth
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19
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1 answer
What dictates the lifetime of a solvated electron in a given solvent?
Solvated electrons have a long lifetime in ammonia solutions, but their counterparts in water (called hydrated electrons) have a much smaller lifetime, of the order of microseconds in very pure water.
(image from: Boero et al, Phys Rev Lett 2003,…
F'x
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19
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1 answer
Propose a chemical formula for the white solid that forms during the initial stages of the reaction of Sn with benzyl chloride
In my inorganic class, we carried out the synthesis of chlorotribenzyltin, $\ce{SnCl(CH2C6H5)3}$.
The synthesis begins with a reflux I'll describe below:
In a hood, place 2.0 g (17 mmol) of 325 mesh tin powder, 4.0 mL of $\ce{H2O}$ and 6.0 mL (6.6…
John Snow
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19
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5 answers
Is lead radioactive?
Is lead (Pb) radioactive? I have heard about it being radioactive but have also heard it referred to as the heaviest stable element. Radioactivity refers to release of alpha, beta, gamma rays.
user15758
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19
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1 answer
What is the hybridization of the carbonyl oxygen in a carboxylic acid?
My professor sent out a review guide. One of the questions on this guide is
The carboxylic acid carbonyl oxygen is:
1. $\ce{sp^2}$
2. $\ce{sp^3}$
3. $\ce{H}$-bond donor
4. rapidly equilibrating between $\ce{sp^3}$ and $\ce{sp^2}$
5. 1…
user15750
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19
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3 answers
What is the mechanism of chlorosulfonation of benzene?
The above reaction looks very similar to a conventional sulfonation reaction but if the reaction pathway is analogous to sulfonation I do not see how the $\ce{SO_2Cl^+}$ would form. Surely $\ce{Cl^-}$ would leave rather than $\ce{H_2O}$ in the…
RobChem
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19
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3 answers
Why is a hydroxyl group more activating than a methoxy group in electrophilic aromatic substitution?
Why is phenol more reactive towards electrophilic substitution than methoxybenzene? Isn't the lone pair on the methoxy group oxygen more available for participating in resonance into the ring than the lone pair on hydroxyl oxygen due to the +I…
Dhruba Banerjee
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19
votes
2 answers
How does volume contraction in solvent mixing work?
I recall seeing chemistry demonstrations where a significant amount of a solute is dissolved in a solvent and the solution volume barely changes. Questions regarding this:
1) How is this possible?
2) What solvent/solute combinations best demonstrate…
docscience
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19
votes
4 answers
What is the difference between physical and chemical bonds?
If you characterize the chemical bonds to two categories physical and chemical bonds, how do you do it? Aren't all bonds chemical and physical?
From the freedictionary.com, chemical bond:
Any of several forces, especially the ionic bond, covalent…
Juha
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19
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1 answer
Why concentrated sulfuric acid for dehydration and dilute for hydration?
To dehydrate ethanol one uses concentrated sulfuric acid:
$$\ce{C2H5OH ->[\text{conc.} H2SO4] C2H4 + H2O}$$
but to go in the reverse direction, dilute sulfuric acid is used:
$$\ce{C2H4 + H2O ->[\text{dil.} H2SO4] C2H5OH}$$
Why is one concentrated,…
QCD_IS_GOOD
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19
votes
2 answers
Which is the more stable enol form?
If I understand correctly, when we go from a keto to an enol form, we simply abstract an alpha proton and thereby create a double bond to a carbon-bearing the hydroxyl functional group.
When evaluating the stabilities of the two enol forms, it…
Dissenter
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Why does Nitrogen form N₂ (and not N₄) while but Phosphorus forms P₄ (and not P₂)?
$\ce{N2}$ is a gas
$\ce{P4}$ is a solid
$\ce{N}$ and $\ce{P}$ are in the same group in the periodic table
The bond enthalpies are:
$\ce{N#N}$ triple bond is $949~ \mathrm{kJ/mol}$
$\ce{P#P}$ triple bond is $490~ \mathrm{kJ/mol}$
$\ce{P-P}$ single…
user5181
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19
votes
1 answer
Is KF the most ionic compound?
I saw somewhere (can't recall where) that KF is the most ionic compound. I expected CsF. Does the greater polarizability of Cs allow it to more easily form covalent bonds compared to K? Does this overcome the fact that K being in n = 4 should…
Brinn Belyea
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