Questions tagged [hydrogen-bond]

Bond between covalently bound hydrogen atom and atom possessing a lone pair of electrons.

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Does increasing # of hydrogen bonds decrease the strength of these bonds?

I saw the question, "Is the strength of hydrogen bonding greater in hydrogen peroxide or water?" and it made me think of a question on hydrogen bonding: If an oxygen on a water has a ...
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Physical significance of double-well potential in quantum bonding

I'm currently studying about the hydrogen bond's Potential Energy Surface (PES) pattern. As per literature, single point energy obtained from Density Functional Theory (DFT) using MP2 approximation ...
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Diazo Coupling reaction with para-substituted phenol?

Usually Diazo coupling occurs at para-position unless the para-position is occupied, in which case coupling occurs at ortho-position. While solving questions I found in both the cases as shown, the ...
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Hydrogen bond strength of trichloromethane and chloromethane

Chloromethane has a larger dipole moment than trichloromethane. Does that mean that the hydrogen bond (C-H...O type) between chloromethane and acetone is stronger than that of trichloromethane and ...
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Strongest hydrogen bond between neutral molecules?

It is known that very strong hydrogen bonds can occur in charged systems, such as $\ce{[F-}\ce{-H+-F-]}$, while hydrogen bonds in neutral systems are much weaker in comparison. What is the strongest ...
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Tools for investigating hydrogen bonding

What would be the best tool to investigate local molecular organization in liquid mixtures due to hydrogen bonding? For example, I might want to look at how water molecules hydrogen bond to PNIPAM vs ...
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Does alcohol hydrogen in the enol tautomer of a β-dicarbonyl have sp² character?

My reasoning for the somewhat implausible "$\mathrm{sp^2}$" character of the hydrogen between these two oxygens on the enol structure of the right comes from recognizing that if it were, then we would ...
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Examples of intramolecular hydrogen bonding closing bond angles

Okay, we've established that intramolecular hydrogen bonding can exist in molecules, and doesn't always serve the purpose of closing the bond angle at least relative to other stereoisomers of the same ...
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Why ethyl cyanide and propanol have the same boiling point?

As I understand, the intermolecular forces of ethyl cyanide are of van der Waals nature (dipole-dipole) but in the propanol molecule there are hydrogen bonds which are in principle much stronger. Why ...
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Extent of Hydrogen bonding in H2O2

Several books that I have read say that in $\ce{H2O2}$ the degree or extent of H-bonding is 6 as each H atom would form 1 and O atom would form 2 H-bonds respectively. However if we look at HF the no....
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Why does Pubchem show cis-1,3-cyclohexanediol with the hydroxyls in the equatorial position?

I am a beginning organic chemistry student and trying to reason about something based on information in my book, but seeing that Pubchem gives a different structure than I'd expect. In considering a ...
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Hydrogen bonds: 1 donor with 2 acceptors at the same time possible (or vice versa)?

Can 1 donor (eg N-H) facilitate 2 H-bonds with 2 different acceptors (eg 2x O) at the same time (assuming that both are within range and angle constraint)? i.e. building an "h-bond triangle"? Is it ...
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Would the hydrogen-bonded polymer hexaamminecobalt(III) hexakis(trifluoromethyl)cobaltate(III) be soluble in water?

It is clear that both the hexaamminecobalt(III) ion and the hexakis(trifluoromethyl)cobaltate(III) ion are both low spin (the former is already low spin, and the trifluoromethyl ligand is clearly ...
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which oxygen atom make intramolecular hydrogen bond in salicyclic acid?

When I googled about intramolecular hydrogen bonding in Salicylic acid, I found that there are two type of hydrogen bonding. Which one is more appropriate? And another question, if there ARE two ...
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Hydrogen Bonding by Carbenes

A hydrogen bond is formed between hydrogen attached to highly electronegative atoms (nitrogen, oxygen, and fluorine) which are small in size too and the non-bonding pair of electrons of another such ...
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Hydrogen Bonding in Water (MO theory)

Valence Bond Theory tells us that each of the “sp3” (in reality, 44% s character) oxygen line pairs in water can act as electron donors, but observing the MO diagram for water tells us that the 2 non-...
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It is easier to iron cotton clothes when slightly wet, why?

As the title says, why is it easier to iron cotton clothes when slightly damp ? Has this got something to do with the hydrogen bonding in cotton ?
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reference or data on internal hydrogen bond strength

As suggested by the title, I am looking for data on the strength of different internal hydrogen bond configurations. In general, an internal hydrogen bond may form when the donor and acceptor are ...
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What happens when hydrogen bonds stretch?

I'm researching about the Mpemba effect and I came across an explanation saying that the effect occurs because at higher temperatures, the hydrogen bonds between the water molecules stretch and store ...
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Do CHF3 and acetone form a hydrogen bond?

I haven't been able to find a reference confirming that fluoroform forms hydrogen bonds with acetone. Do they?
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Comparing the boiling points of common organic molecules

The order I was provided with is(comparing molecules of similar molecular mass from each); alkanes< ethers< esters< aldehydes< ketones<< alcohols<< carboxylic acids<< ...
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Hydrogen bonding in acetylene and other terminal alkynes

My textbook says that hydrogen bonding is possible only when there is acidic hydrogen connected to an electronegative atom like $\ce{N}$, $\ce{O}$ or $\ce{F}$ and a basic lone pair of electrons on ...
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Why aren't the hydrogen bonds in carboxyllic acids like this?

Why don't carboxylic acids form H-bonds in this formation with the red dots (diagonal) instead of the black dots (horizontal)? I was always taught that H-bonds formed between partially negative and ...
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Water solubility comparison of stereoisomers of bicyclo [4.4.0] decane-3,4-diol

I think, (I) must be more soluble in water. It is due to trans configuration and thus, forming more effectively inter-molecular hydrogen bonds with water molecules.
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Factors dominating forces between acetone and chloroform

What type of interaction is present between acetone and chloroform? According to me, acetone has weak hydrogen-bonds with chloroform, the hydrogen on an electronegative atom has electron density that ...
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Increase of peak intensity in case of hydrogen bonding

Typical motif in case of hydrogen bonds is charge transfer from electron rich acceptor Y to (usually) anti-bonding X-H σ* orbital. If so, the X-H bonding distance increases, bond weakens, stretching ...
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Explain the effect of intramolecular hydrogen bonding on solubilities in cold and hot water?

There is a statement given in my textbook (Cengage, Organic Chemistry (Part 1), page 4.33) which is as follows: (I edited the statement to make it simpler) One can account for the solubilities of ...
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How to characterise lipophilicity?

I was provided with a drug compound which is filling a hydrophobic pocket. The R group is changed and effects on the potency was measured; $\ce{R = -H, -CH3, -CH2F}$ were tested. As expected, the more ...
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How to determine the pH range at which maximum hydrate is present?

Question: Find the $\mathrm{pH}$ range at which maximum hydrate is present in a solution of oxaloacetic acid (given $\mathrm{pK_a}$ of $\ce{-COOH}$ in the left is $=2.2$ and on the right is $=3.98$): ...
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How do water molecules overcome the van der waals distance and form hydrogen bonds?

I read in Voet & Voet that the hydrogen bonds are at least 0.5 angstrom shorter than the calculated van der waals distance. As I understand, van der waals distance is the distance of closest ...
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Comparing strengths of Hydrogen Bonds

What kind of a bond is the Hydrogen bond? Is it electrostatic forces of attraction or more like a partial coordinate bond? What pair of atoms would provide us the strongest Hydrogen bond? If we ...
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Hydrophobic effect/interactions

$\text{Water molecules cause hydrophobic interactions because:}$ $\text{A- they can disrupt surfaces with no hydrogen bonds.}$ $\text{B- they prefer to be close to hydrophobic surfaces}$ $\text{C- ...
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DI water vs. Tap water in ethanol-water and salt phase change reaction

We did a very simple lab like one you would do in highschool showing that you can seperate the phases of water and ethanol using salt. As simple as it sounds, we could not get it to work no matter ...
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What are the necessary conditions for formation of a Hydrogen Bond?

Usually Hydrogen bonds are associated with N,O,F as the atoms involved. In some cases OH---Cl bond is observed as in case of o-chlorophenol. According to the updated IUPAC definition a Hydrogen bond ...
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Why does steam store large amounts of energy?

We all know that steam can be used to perform mechanical work and steam has a high capacity for energy storage. But why does steam have such high energy capacity? I tried searching for answers on the ...
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Are hydrogen bonds between two hydroxyl groups stronger if one is deprotonated?

Hydrogen bonds can form between two hydroxyl groups. Is the hydrogen bond stronger if one of the groups is deprotonated?
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Why isn't there a hydrogen bond present between the oxygen atom and hydrogen atom of adjacent alcohol groups?

*I know that there is inter-molecular hydrogen bonding between the molecules of glycerol. *What makes the adjacent alcohol groups behave differently towards each other as compared to when they ...
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How the attraction takes place between a hydrogen atom and the acceptor atom in a hydrogen bond

In hydrogen bonds present in water,does the hydrogen atom attracts to the lone pair of electrons present on the oxygen atom or to its partial negative charge? If former is the case are there any ...
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Effect of intramolecular hydrogen bonding on the stability of a molecule

What will be the effects of intramolecular hydrogen bonding on the stability of a molecule? Will it increase or decrease the overall stability of a molecule? Or will it not have any impact on the ...
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Why does energy need to be "compensated" in order for solvation to occur?

I am currently learning about the physical properties of alcohols. I understand that the main intermolecular forces between alcohols and water are hydrogen bonds. When these two are mixed, the ...
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Why is boiling point of Ammonia greater than Arsine?

I have previously read that the boiling point of Stibane(SbH3) is greater than Ammonia(NH3) as ammonia is gas at room temperature and no hydrogen bonding exists in the gaseous form of NH3. Hence, as ...
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Number of hydrogen bonds of organic compounds?

How to count the organic molecules ' hydrogen bonds in average? What are the numbers of hydrogen bonds formed among alcohols ,alkanoic acids ,aldehyde , ketones , amine ,amide , and ether when they ...
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Why Aren't Alcohols Weak Bases?

I was reading about alcohols being weak acids because they are deprotonated in water, presumably because the $O-H$ bond is being overcome by hydrogen bonding between $H$ in the hydroxyl group and $O$ ...
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