All Questions
Tagged with intermolecular-forces organic-chemistry
62 questions
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2
answers
159
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Cucurbiturils and cyclodextrins — what is the difference?
One was reading about the cyclodextrins on this site and decided to further investigation on the matter. One encountered a class of molecules called cucurbiturils, which are macrocyclic molecules that ...
- 11
7
votes
1
answer
233
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Cyclodextrins: Is there really a hydrophobic interior and hydrophilic exterior?
I do not get most of the explanations on why cyclodextrins are so good at hosting hydrophobic molecules. It is true that the hydroxyl groups are pointed outwards and thus the cavity is definitely less ...
- 85
0
votes
0
answers
55
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Melting Point Order of Benzene Derivatives
Q)Compare the melting points of the following?
o-Hydroxybenzaldehyde
o-Methoxybenzaldehyde
p-Hydroxybenzaldehyde
p-Methoxybenzaldehyde
My attempt: Intermolecular H-bonding increases melting point ...
- 77
3
votes
1
answer
619
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Why does N,N-dimethylethanamide have a higher boiling point than butanoic acid?
According to Wikipedia, N,N-dimethylethanamide has a boiling point of $\pu{165.1 °C},$ while butanoic acid has a boiling point of $\pu{163.75 °C}.$
From what I learned, butanoic acid should have a ...
- 281
1
vote
0
answers
51
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Air/Acetonitrile Interfaces
Say I drop some acetonitrile on a grounded surface and it forms a meniscus. The acetonitrile is in air. Lets forget about evaporation for the moment.
Will there be an interfacial dipole formed by the ...
- 648
1
vote
0
answers
280
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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?
- 55
3
votes
1
answer
161
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What are the limits of size differences in a host–guest complex?
We learn in my chemistry course that there must be a snug fit for a host-guest complex to form. So, something like benzene (0.6 nm in diameter) can form a host-guest complex with a β-cyclodextrin host ...
user107675
6
votes
1
answer
916
views
Intermolecular forces of attraction between positional isomers of alcohols
This seemingly trivial question is as follows: Why is the boiling point of 1-butanol ($\ce {117.7 ^\circ C}$) higher than that of 2-butanol ($\ce {99 ^\circ C}$)?
The only reason I can think of is ...
- 10.8k
2
votes
1
answer
2k
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Why does Ethylene Glycol have higher boiling point than Propylene Glycol?
Looking at the two alcohols, both have hydrogen bonding and are singly bonded throughout the molecule. However, propylene glycol has a larger electron cloud which to my knowledge would increase its ...
- 31
8
votes
1
answer
5k
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Why are hydrogen bonds in an antiparallel beta sheet stronger than those in parallel beta sheets?
Beta sheets are illustrated as such in most diagrams, where:
In an antiparallel β-sheet, the polypeptide strands are arranged such that a $\ce{C=O}$ and an $\ce{NH}$ from adjacent strands face each ...
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27
votes
1
answer
4k
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Anomalous boiling point of "iso-" alkanes
I was attempting to compare the boiling points of iso-hexane and 3-methylpentane.
Boiling points of organic compounds depend upon three factors according to Master Organic Chemistry – 3 Trends That ...
- 7,050
7
votes
2
answers
1k
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Do amines or alcohols have stronger intermolecular hydrogen bonds?
Which has stronger hydrogen bonding, $\ce{CH3OH}$ or $\ce{CH3NH2}$
I think it comes down to which has more dominance; number of hydrogens, number of lone pairs, or electronegativity.
- 1,051
0
votes
1
answer
2k
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Why is the boiling point of ethyl fluoride lower than that of hydrogen fluoride?
The book, Solomons' Organic Chemistry (for JEE Mains and Advance), contains the following question:
Hydrogen fluoride has a dipole moment of $\pu{1.82 D}$; its boiling point is $\pu{19.34 ^{\circ} ...
user88957
1
vote
0
answers
1k
views
Solubility of alcohols in non-polar solvents
The solubility of an alcohol in a non-polar solvent (like hexane) increases with size of the alcohol, as the non-polar chain increases. However, as the chain keeps increasing, will the solubility ...
- 51
-2
votes
1
answer
49
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How big does an atom need to be to have dispersion forces be greater than other intermolecular forces? [closed]
I know as an atom gets bigger the dispersion forces grow with it. But how big does an atom, e.g methanoic acid, to have dispersion forces that outrank dipole-dipole forces?
0
votes
0
answers
99
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Stability of alkenes
The following question was asked on myPAT website:
I started with the solution by counting the hyper-conjugative structures available to each alkene. Based on this concept only, order is:
I > ...
- 3,081
0
votes
0
answers
704
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Which has a high melting point, cocoa powder or cocoa butter?
I have been doing some research into chocolate, and after looking at the chemical compositions of cocoa butter and cocoa powder, struggled to determine which had a formula/structure that would have a ...
0
votes
0
answers
39
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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 ...
- 339
2
votes
1
answer
2k
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Boiling point of ethanamide vs propanamide
I just have a question regarding the boiling points of some primary amides. Ethanamide has a boiling point of 222 °C, while propanamide has a lower boiling point of 213 °C. Both amides are capable of ...
- 467
2
votes
0
answers
276
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What type of interactions occur when CH4 dissolves in CCl4 [duplicate]
When ionic compounds dissolve in polar solvents many types of factors come into play determining their solubility. Some of them may be: ion- dipole interactions, lattice energy, high dielectric ...
- 197
2
votes
3
answers
972
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If all intermolecular forces are electrostatic in nature, why don’t large non polar molecule dissolve in water?
If I have a large non-polar substance A that forms strong dipole-induced dipole force (DIDF) with water, with strength comparable to that of H-bonds between water molecules, will A dissolve in water?
- 37
1
vote
1
answer
956
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Intermolecular interaction between aniline and dichloromethane
Short background
As it is known there are interactions between:
Charges
Charge and dipole
Hydrogen bonding
van der Waals (VDW) forces
From stronger (1) to weaker (4).
VDW forces are divided into ...
user43021
2
votes
1
answer
127
views
Relating properties and structures of polymers
Why would it be more favorable for a polymer designer to design copolymers with irregular chain structures, rather than design homopolymers?
Hint: Discuss intermolecular bonds
I understand that ...
- 83
0
votes
1
answer
174
views
What are the intermolecular forces between polychloroethylene?
Does polychloroethylene have only van der Waals/London forces between its molecules? Surely, if all the chlorine atoms are on one side, due to the fact that chlorine is more electronegative than ...
- 11
1
vote
0
answers
19
views
How to know if a sample suffered descomposition during melting point? [closed]
If I take a sample in order to determine its melting point, how do I know if that sample suffered a descomposition?
- 49
3
votes
0
answers
91
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Why is this scintillator component turning into a milky-white emulsion?
I am a chemistry and physics double major doing some chemistry work in a nuclear physics lab. My mentor is a physicist, so his area of expertise is occasionally mismatched with what I need for my ...
- 131
1
vote
1
answer
5k
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Why does acetone have a lower boiling point than hexane?
Why does acetone have a lower boiling point than hexane? I thought that since hexane is non-polar then it should have weaker intermolecular forces and a lower boiling point, but it doesn't. Why?
For ...
- 19
5
votes
1
answer
2k
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For two compounds that are symmetrical, why does the more compact one have a higher melting point?
In this post, I refer to two molecules B (Di-tert-butyl ether) and C (Dibutyl ether).
Wikipedia: Di-tert-butyl ether (B)
b.p. 107.2 C
m.p. - 61 C
...
- 155
13
votes
1
answer
405
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Possibility of π–π stacking in non-aromatic systems
Is it possible to have π–π stacking for non-conjugated double bond systems?
For example, can the carbonyl groups of two urea molecules participate in π–π stacking? Although urea prefers to stay in ...
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17
votes
2
answers
4k
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Why are fluoroalkyl chains hydrophobic/oleophobic?
I'm searching for an answer that explains the hydrophobicity / oleophobicity in terms of intermolecular forces, but can't really find one.
Below is an example fluoro-alkyl nano-particle, F-POSS. It ...
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1
vote
2
answers
266
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Why a particular enantiomer of a diastereomer shows affinity towards another? [closed]
A particular enantiomer can show affinity towards another enantiomer of another diasteromer eg. body receptors with chiral drugs, chiral stationary phase of chromatography etc.
But what's the reason ...
- 279
5
votes
2
answers
2k
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Why do alkenes with more surface contact have greater London forces?
Why is it that alkenes with greater surface contact have greater London forces? I thought greater London forces were dependent on the size of the molecules, or the number of electrons, rather than the ...
- 51
1
vote
2
answers
7k
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Why does branching decrease density and melting point?
The general explanation given is that the chains are further apart, so the intermolecular forces are less, and as they are further apart, they occupy more volume, and the density is lesser. But the ...
- 495
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1
answer
9k
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Which of these functional groups is soluble in aqueous HCl and/or NaOH?
http://pastpapers.papacambridge.com/view.php?id=Cambridge%20International%20Examinations%20%28CIE%29/AS%20and%20A%20Level/Chemistry%20%289701%29/2015%20Jun/9701_s15_qp_42.pdf
I need some help to ...
- 495
2
votes
2
answers
458
views
Why is polymer B more dense than polymer A?
The official solution is that A has branched / side chains, weak Van der Waals forces between the polymer chains, less compact packing than B, and large inter-chain distances.
B has no branched chains,...
- 495
2
votes
1
answer
2k
views
How does cross-linking between polymer chains increase the melting point of the polymer?
https://i.sstatic.net/uUcQr.jpg
Suppose we have this polymer chain. Now, we cross link some chains ( not all ) , so some chains get linked, and others remain as they are. What we now have is a '...
- 495
4
votes
1
answer
154
views
Do dipole dipole interactions need to be added explicitly to vdW forces while doing DFT simulations for organic molecules?
I am modelling the adsorption of organic molecules on metal surfaces using plane-wave dft. While there is literature on how important van der Waals forces are for organic systems, and there are also ...
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7
votes
1
answer
229
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Computational Chemistry: calculation of sterical effects
Is there a way to calculate sterical forces between atoms/groups of atoms (preferably with free and open source tools)? I have heard that this is possible within the framework of NBO. I am using ORCA, ...
- 2,804
1
vote
1
answer
3k
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Range of distance for Van der Waals force
Is there any range of distance between the nuclei of the atoms (in Angstrom, say between 4 to 12 Angstrom) within which there will be an occurrence of Van der Waals force (attraction) between them?
...
- 535
4
votes
1
answer
14k
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Why do alcohols and ethers have approximately the same solubility in water but different boiling points?
In Morrison & Boyd, I found this question:
Butan-1-ol (b.p. $118~\mathrm{^\circ C}$) has a much higher boiling point than its isomer diethyl ether (b.p. $35~\mathrm{^\circ C}$), yet both ...
- 851
5
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0
answers
5k
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Intermolecular Forces in Teflon vs Polyethylene
From Wikipedia, polyethylene has a melting point of around $400K$, while Teflon (polytetrafluoroethylene) has a melting point of $600 K$, which is much higher. Besides the increased London Dispersion ...
- 1,620
1
vote
2
answers
1k
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Correlation between functional group and viscosity of an organic compound?
I'm looking to explore the correlation between the type of functional group on an organic molecule and the viscosity of the compound. I know that viscosity is affected by intermolecular forces (Ion-...
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0
votes
1
answer
5k
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Trying to understand the causes and implications of kinks in fatty acid chains
I watched this video (The Deal with Fat by SciShow):
https://www.youtube.com/watch?v=mvvx2yQRbzQ
To summarize the main points I want to discuss:
Saturated fats are chains without any double-bonds ...
- 73
7
votes
1
answer
854
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How does fluorouracil inhibit thymidylate synthase?
I'm curious to know how just by adding a fluorine atom to uracil (to form 5-fluorouracil) permanently inhibits the enzyme thymidylate synthase when they bind together. This molecule is widely used as ...
- 225
0
votes
0
answers
456
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What happens to the attraction of glycerol to a positively charged acetate rod if water is added
I know that glycerol is more polar than water because it has stronger intermolecular forces and its also more viscous. If I were to add water to a glycerol solution, would the solution get less polar ...
2
votes
1
answer
6k
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Why the boiling point decreases with increase in branching in alkyl groups?
I found out the answer is that
with increase in branching, the molecules attain a spherical shape with less surface area. As a result, interparticle forces become weaker resulting in lower boiling ...
- 21
4
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2
answers
2k
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Basis for the hydrophobic effect?
I'm confused about why hydrophobic molecules, which do not have high polarity, would have a tendency to attract and cluster with themselves. It is easier to understand the hydrophilic as long as one ...
- 1,648
21
votes
5
answers
10k
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Strength of hydrogen bonding in phenol or methanol
I wanted to know whether hydrogen bonding is stronger in phenol or methanol.
I saw on Wikipedia about the enthalpies of hydrogen bonding in various cases.
but could not find the answer to this ...
- 211
11
votes
1
answer
138k
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Alkane, alkene, alkyne boiling point comparison
Which of the following has higher boiling points? Alkanes, alkenes, or alkynes? And why?
- 173
3
votes
1
answer
191
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How to get a protein's dihedral angles ordered by variance?
The setting: I want to simulate protein docking and let some dihedral angles vary, but in order to keep it low-dimensional I have to select those which are most likely to change.
What I've thought of ...
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