Questions tagged [organic-chemistry]

Use this tag for questions relating to organic molecules and their properties (structure of organic molecules, spectroscopic properties, reaction mechanisms, stereochemistry etc). DO NOT use this tag as the only tag in your question, as this tag by itself cannot appropriately classify your question. Always use this tag in addition to other more specific tags.

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109
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1answer
5k views

Is there a general consensus on the causes of the alpha-effect?

There have been various explanations posited for the α-effect. The α-effect refers to a phenomenon wherein nucleophiles with lone pairs on atoms adjacent (i.e., in the α- position) to the atom bearing ...
75
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5answers
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How do people know HCN smells like almonds?

I was told by my chemistry teacher that $\ce{HCN}$ smells like almonds. She then went on to tell a story about how some of her students tried to play a prank on her by pouring almond extract down the ...
72
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7answers
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Ortho-effect in substituted aromatic acids and bases

When comparing o,m,p-toluidine basicities, the ortho effect is believed to explain why o-toluidine is weaker. But when comparing o,m,p-toluic acid basicities, the ortho effect is stated as a reason ...
69
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3answers
4k views

How do organic chemistry mechanisms become accepted?

Now I have been learning chemistry for five years. I remember when I started organic chemistry, it was fun to draw arrows between molecules to show, as if in a mathematical demonstration, how the ...
51
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4answers
59k views

Is carbon dioxide organic or inorganic?

Today in chemistry class we were discussing Organic Chemistry. We discussed what organic compounds basically are and then I asked the teacher whether $\ce{CO_2}$ is organic or not. She told that it is ...
51
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2answers
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Regioselectivity of acid-catalyzed ring-opening of epoxides

Not to be confused with what is the mechanism of acid-catalyzed ring opening of epoxides. What is the correct order of regioselectivity of acid-catalyzed ring-opening of epoxides: $3^\circ$ > $2^\...
46
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2answers
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Why does nitration of N,N-dimethylaniline occur at the meta position?

The nitration of N,N-dimethylaniline with $\ce{H2SO4}$ and $\ce{HNO3}$ gives mainly the meta product, even though $\ce{-NMe2}$ is an ortho,para-directing group. Why is this so?
46
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3answers
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Is buckminsterfullerene aromatic?

According to Wikipedia, The $\ce{C60}$ molecule is extremely stable,[26] withstanding high temperatures and high pressures. The exposed surface of the structure can selectively react with other ...
46
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1answer
28k views

Mechanism of arene side chain oxidation by permanganate

When treated with hot, concentrated acidic $\ce{KMnO4}$, arenes are oxidised to the corresponding carboxylic acids. For example, toluene is oxidised to benzoic acid. I've tried to examine how this ...
44
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1answer
7k views

What's the biggest organic molecule that could have a smell?

For a molecule to have a smell it's necessary that the molecule be volatile enough to be in the air. So I think that excludes molecules which are solid at room temperature and atmospheric pressure. ...
44
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3answers
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What is the reason for the exceptional stability of the cyclopropylmethyl carbocation?

Can someone explain this to me by drawing resonance structures for the cyclopropylmethyl carbocation please? Also one more question, is the tricyclopropylmethyl carbocation more stable than tropylium ...
43
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7answers
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How can carbon dioxide be converted into carbon and oxygen?

How can $\ce{CO2}$ be converted into carbon and oxygen? $$\ce{CO2 -> C + O2}$$ Alternatively: $$\ce{CO2 + ? -> C + O2}$$ I'm aware that plants are capable of transforming $\ce{CO2 + H2O}$ to ...
43
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2answers
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Inductive effect of hydrogen isotopes

Why does the electron-donating inductive effect (+I) of the isotopes of hydrogen decrease in the order $\ce{T} > \ce{D} > \ce{H}$? (where T is Tritium and D is Deuterium) Google has nothing to ...
42
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1answer
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Differences between phenols and alcohols

I know phenols are more acidic as compared to alcohols, but are they considered different from alcohols? Sure, you can study something as a subset, but are phenols considered a subset of alcohols, or ...
40
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3answers
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Do molecules with bridges through rings exist?

Do molecules with bridges through rings (in a manner illustrated by this) exist? I sometimes get results like this when doing Energy Minimization on molview.org. For example: Is this actually a ...
40
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2answers
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Why does cyclopropane react with bromine?

In my exam, I was asked why cyclopropane could decolourise bromine water (indicating that it reacted with the bromine). All I could guess was that it is related to the high angle strain in ...
40
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2answers
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Why do SN1 and SN2 reactions not occur at sp2 centres?

I was told in my organic chemistry course that $\text{S}_\text{N}1$ and $\text{S}_\text{N}2$ reactions did not occur at $\text{sp}^2$ centres. When I asked why, I was not given a satisfactory ...
39
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4answers
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Five-pointed crown alkane C25H40: does it exist?

My 4 year old granddaughter, playing with molecular models, began making a cyclopentane ring, each of whose carbons bore a spiro-connected cyclopentane ring of its own , in the manner of spiro[4.4]...
39
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3answers
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Is Hexafluorocyclohexane the "Most Polar" Small Molecule?

Earlier this year, there was a lot of attention when all-cis 1,2,3,4,5,6-hexafluorocyclohexane was synthesized*: Notably, C&E News quoted the lead author: This compound is remarkable for being ...
37
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5answers
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Why does alcoholic KOH prefer elimination whereas aqueous KOH prefers substitution?

What is the basic difference between aqueous and alcoholic $\ce{KOH}$? Why does alcoholic $\ce{KOH}$ prefer elimination whereas aqueous $\ce{KOH}$ prefers substitution?
37
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2answers
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Why is pyrimidine less basic than pyridine?

From Wikipedia's article on pyrimidine: Because of the decreased basicity compared to pyridine, electrophilic substitution of pyrimidine is less facile. But why is pyrimidine less basic than ...
37
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1answer
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What is a non-classical carbocation?

What is a non-classical carbocation? How is it different from a classical carbocation? I am confused as I have come across this term many times on Chem.SE but there seems to be nothing for my level ...
36
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3answers
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IUPAC nomenclature: "Smallest sum of locants"?

While naming any compound, the numbering should be done such that position of substituted groups gives smallest sum. I'm struggling with the IUPAC naming for cyclic compounds. How exactly does this ...
36
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2answers
2k views

IUPAC nomenclature for an interesting looking organic compound

How can I name this organic compound while adhering to the IUPAC standards?
35
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3answers
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Chemistry behind Gale's coffee maker in Breaking Bad

Is there a scientific basis for the coffee making equipment which Gale Boetticher describes in Breaking Bad? He talks about maintaining the right conditions for bringing out the coffee flavor without ...
34
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4answers
16k views

Is pyrene aromatic despite failing Hückel's rule?

Pyrene doesn't seem to be aromatic. However, sources claim that it is aromatic. Considerations: Pyrene is cyclic. ✓ Pyrene is flat (planar). ✓ Pyrene has 16 π electrons. Every atom in the ring ...
34
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1answer
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Stereoselectivity of dihydroxylation with osmium tetroxide

Dihydroxylation responds to steric effects and proceeds at less hindered positions. What will be the major product in the following reaction if the reagent used is $\ce{OsO4}$ followed by $\ce{NaHSO3}$...
33
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4answers
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Why is methanol toxic?

There are two points of view for the answer of this question: The biological view, the only one that I faced during my research, states that since it can trigger perilous conditions like metabolic ...
33
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2answers
166k views

How do I extract cyanide from apple seeds?

I'm working on a crime story about cyanide poisoning from apple seeds. I just would like to have an idea of what processes and extraction techniques might be involved in getting cyanide from the seeds....
33
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3answers
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Why can't Pd/C and H2 reduce both the alkene and carbonyl portions of α,β-unsaturated carbonyls?

Why is it that the major product of the reduction of chalcones the ketone and not the monoalcohol? In other words, Why isn't the major product a benzyl alcohol? From what I understand, catalytic ...
33
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1answer
54k views

Acidity of substituted phenols

Phenol has a $\mathrm pK_\mathrm a$ approximately equal to $9.9$. When one studies the acidity of chlorophenols, one notices the following: First of all, chlorophenols are more acidic than phenol, ...
32
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1answer
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Is the ammonium substituent (-NH3+) really meta-directing in electrophilic substitution?

If we make a resonance structure for the anilinium ion, with positive charge at either the ortho or the para position, we get a pentavalent nitrogen, which is not possible. So, how is the $\ce{-NH3+}$ ...
32
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4answers
62k views

What's the difference between a nucleophile and a base?

Obviously it depends on the context whether you would call a particular species a nucleophile or a base but are the two terms largely synonymous or is there a difference?
32
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1answer
919 views

Why does hyperconjugation help for ring cleavage?

The question was to rationalize it the ring cleavage happens concerted or non-concerted. The papers "The Mechanism of the Thermal Decomposition of 1-Pyrazolines and Its Relationship to ...
31
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2answers
75k views

What are the meanings of dotted and wavy lines in structural formulas?

So I came across this diagram,the other day: As a chemistry student, I am well-versed with the dashed and wedged lines, but I was wondering what the wavy and the dotted line represent?
31
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1answer
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Relative stability of cis and trans cycloalkenes

Why is the stability of (Z)-cyclodecene 2 greater than that of (E)-cyclodecene 1? I'd think that since 1 contains a trans double bond instead of a cis double bond, it should experience less steric ...
31
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1answer
19k views

Why does the unstabilised Wittig reaction selectively form cis alkenes?

This question is meant for a simple unstabilised ylide. The mechanism of the Wittig reaction, as given on ChemTube3d, involves a concerted formation of the oxaphosphetane (this is generally favoured ...
30
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4answers
7k views

Why is '-ethane' in 'methane'?

Is there a chemical or historical significance in the fact that 'ethane' is just 'methane' without the 'm'?
30
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3answers
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Are graphite and hexagonal boron nitride aromatic

Are graphite and hexagonal boron nitride aromatic? Graphite has a planar network of 6-membered rings with each carbon connected to three other carbons. Since the valency of carbon is not satisfied, ...
29
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3answers
9k views

Why does chocolate melt so easily?

(Yes, I know the question sounds super-trivial... but bear with me here) Most chocolates (especially milk-chocolate) tend to melt into this sticky (albeit delicious) mess at temperatures slightly ...
29
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3answers
2k views

Why is 1-ethylidene-4-methylcyclohexane chiral?

As far as I can tell, there doesn't seem to be a chiral carbon in this compound. C-4 of the cyclohexane ring has two groups with exactly the same connectivity, and the exocyclic double bond can't give ...
29
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2answers
3k views

Why is −78 °C a magic temperature for organic reactions?

In many organic reactions that I have seen, running the reaction at $\mathrm{-78\ ^\circ C}$ seems to be quite a popular choice, but I've never seen any explanation for this. What makes this ...
29
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4answers
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Why are DCM and chloroform so resistant towards nucleophilic substitution?

In the book Organic Chemistry by J. Clayden, N. Greeves, S. Warren, and P. Wothers I found the following reasoning: You may have wondered why it is that, while methyl chloride (chloromethane) is a ...
29
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1answer
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Unusual Friedel–Crafts alkylation with pivaloyl chloride

In class we were told of an anomalous Friedel–Crafts reaction with a tertiary acid chloride — $\ce{(CH3)3CCOCl}$, or pivaloyl chloride. When this reacts with benzene in the presence of $\ce{AlCl3}$, ...
29
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4answers
9k views

Is activated carbon classified as organic or inorganic?

Organic compounds are typically defined as “molecules containing carbon”. Wikipedia states that there for some historical (read: non-logical) reasons, a few types of carbon-containing compounds ...
29
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1answer
4k views

In what way could benzoin give Tollen's test?

In Q29 of Joint Entrance Exam (JEE) 2016 India, the official answer key mentions that benzoin gives Tollen's test. However, I saw this post which says that it doesn't: Why do α-hydroxy ketones give ...
28
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4answers
23k views

Carbon with 5 bonds?

I've heard that, even though according to Molecular Orbital Theory there is no chance of having nobel gases bonded to each other, it is not totally impossible. For example, under extreme conditions, ...
28
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5answers
55k views

Why are tertiary carbocations the most reactive, if they're already stable?

This may seem silly, but doesn't it seem weird for a compound that's stable (in this context, the tertiary carbocation) to be the most reactive? I mean, wouldn't it be the least, given that it's ...
28
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3answers
64k views

How do you separate enantiomers?

There are some stereochemical reactions that result in the presence of enantiomers. When moving forward with a practical organic synthesis, how does one usually separate them in order to continue with ...
28
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1answer
6k views

Why is cyclooctateraene shaped like a "tub" rather than a "chair"?

I understand that for cyclooctatetraene (COT) to "escape" the horrible prospect of becoming an anti-aromatic molecule, it must adopt a non-planar conformation. The widely touted conformation of COT ...

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