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Synthesis Golf III: Chloramphenicol
A full FAQ post has been written on meta.chem.SE, explaining the premise of synthesis golf and the 'rules'. Please take a look at this before answering (if you haven't already).
This third round of golf concerns the synthesis of chloramphenicol…
NotEvans.
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Are there any examples of activating meta directors?
I have heard about activating ortho-para directors. For example: methoxy group, hydroxy group, alkyl group, et cetera.
I have heard about deactivating ortho-para directors. For example: halogen substituents
I have heard about deactivating meta…
Pritt says Reinstate Monica
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Does the number of H+ ions in solution go up on dilution of a weak acid?
In my textbook, a footnote says:
In case of weak acids, on dilution the total number of $\ce{H^{+}}$ ions in solution increases because dissociation of the weak acid increases
This didn't make sense to me however. Consider the general…
Gerard
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Is it possible for a compound to be soluble in a mixture of solvents but not the individual solvents?
Some weeks ago one of my friend needed to use turpentine. As a good but ignorant chemist on that point I did some research about it. I found (at the beginning) in the French wikipedia page of turpentine :
"L'essence de térébenthine est un mélange…
ParaH2
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Can hydrogen on platinum reduce carboxylic acids and esters?
Can $\ce{H2/Pt}$ reduce carboxylic acids and esters?
I am confused about the reducing nature of hydrogen in presence of platinum. In some books, it reduces carboxylic acid and ester while in others, not. I have checked Finar and Boyd books for it.
Arvind Tiwari
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How to calculate wavenumbers of normal modes from the eigenvalues of the Cartesian force constant matrix?
I would like to get the wavenumbers (Frequencies -- in Gaussian) from the eigenvalues of the force constant matrix (Force constants in Cartesian coordinates: in Gaussian).
Could someone please explain how to perform this calculation? The Cartesian…
Roloka
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If aliens lived in a hydrogen (or any flammable gas) based atmosphere, would they perceive oxygen to be flammable?
Energy, fuel, and oxygen are needed for a fire to burn. In a hydrogen chamber, if there was a pipe spewing small amounts of oxygen, could you light the oxygen on fire as it began to mix with the hydrogen?
Howzieky
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67 failures at extracting acetaminophen from Excedrin(R)
I have adapted the lab experiment described in this J. Chem. Ed. article for the organic chemistry lab course I teach. In the past year, the first year of implementation, I have had 67 failures (100% failure rate) on the extraction part of this…
Ben Norris
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Why does the reaction quotient use the products (multiplications) of reactants and products, rather than their respective sums?
As you may know, the reaction quotient $Q_c$ is defined by the equation
$$
Q_c = \frac{[C]^\gamma [D]^\delta}{[A]^\alpha [B]^\beta}
$$
for the chemical reaction
$$
\alpha A + \beta B \rightarrow \gamma C + \delta D.
$$
This is something I've been…
olliezhu
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If capsaicin is insoluble in water, what makes chilli water taste spicy?
I have always been told that the 'heat' from chillies came from capsaicin which is oil based. Recently I began wondering how environmentally friendly chilli based insecticide/repellent sprays could work if they are water based. A chemist friend…
Bella
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Is there a least reactive chemical species?
As a total chemistry layman I enjoyed reading "Why doesn't $\ce{H2O}$ burn?", but it prompted another question in my mind. One of the answers there was that $\ce{H2O}$ can burn in the presence of a stronger oxidizer like fluorine, so burning stable…
David
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When are two orbitals orthogonal?
When are two orbitals considered to be orthogonal?
It will be helpful if you can provide an example molecule (or molecular orbitals in a molecule) since I can't really think of a scenario where molecular orbitals can be exactly 90° to each…
CPak
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Which carbons in pyrrole have the highest electron density?
In pyrrole, which carbon atoms have the greatest electron density?
In the resonance structures of pyrrole, all carbons can formally bear a negative charge, so it's not immediately obvious which one is most electron-rich:
My book claims that because…
Harini
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Why is the boiling point of stibane higher than that of ammonia?
I recently came across the fact that the boiling point of $\ce{SbH3}$ (stibane) is greater than that of $\ce{NH3}$ (ammonia). I was expecting $\ce{NH3}$ to have a greater boiling point as a consequence of intermolecular hydrogen bonding. I…
Arishta
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What are modern approaches to describe and/or quantify aromaticity?
I know that Schleyer described an approach for evaluating aromaticity using nucleus-independent chemical shifts (NICS, see e.g. Chem. Rev. 2005, 105 (10), 3842–3888) quite some time back. I also somehow have the feeling that there should be a more…
logical x 2
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