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Why is the formation of a peptide bond not spontaneous? I'm not looking for the free energy calculation; I have it from several sources. I'm just asking for an intuitive explanation. Is it because the peptide bond is planar so there's a loss of free rotation and the delta S is unfavorable? Is the resonance stabiliz... |
Why is the formation of a peptide bond not spontaneous? |
I keep seeing the term biosynthetic origin used in medicinal related papers.
Does it just refer to the biological precursors to the molecule?
So, for example, the biosynthetic origin of Paclitaxel is terpenes? |
What is meant by the term 'biosynthetic origin'? |
Earlier I had a student come by wanting to know how to show the dissolution of $NH_4OH$ in water. I would think we would just write it: $$NH_4OH(aq) <=> NH_3(aq) + H_2O(l)$$ I say this as $$NH_4(aq) + H_2O(l) <=> NH_3(aq) +H_3O^+(aq) + OH^-(aq)$$ I am struggling to understand when and why we put the $H_2O$ as a solven... |
Why is the formation of a peptide bond from a carboxylic acid and amine not spontaneous?
I'm not looking for the free energy calculation; I have it from several sources. I'm just asking for an intuitive explanation. Is it because the peptide bond is planar so there's a loss of free rotation and the delta S is unfa... |
Earlier I had a student come by wanting to know how to show the dissolution of $NH_4OH$ in water. I would think we would just write it: $$NH_4OH(aq) <=> NH_3(aq) + H_2O(l)$$ I say this as $$NH_4OH(aq) + H_2O(l) <=> NH_3(aq) +H_3O^+(aq) + OH^-(aq)$$ I am struggling to understand when and why we put the $H_2O$ as a solv... |
In the synthesis of Panacene by Canesi et al, a step involves the installation of an -OH group on a double bond, using the oxymercuration-demurcuration procedure. However, the product happens to be a hemiacetal, as shown in the picture. With a 78% yield, it seems that the hemiacetal is not reactive towards the added so... |
Can sodium borohydride reduce hemiacetals? |
Based on a quite old reference [1] (which I'm using because it's available free by open access), peptide bond formation at 25 C is unfavorable only because of a large enthalpy change, on the order of 1.5 kcal/mol (6.3 kJ/mol). The entropy change is actually favorable, with $T\Delta S$ being about 1 kcal/mol (4kJ/mol)... |
In the synthesis of Panacene by Canesi et al, a step involves the installation of an -OH group on a double bond, using the oxymercuration-demercuration procedure. However, the product happens to be a hemiacetal, as shown in the picture. With a 78% yield, it seems that the hemiacetal is not reactive towards the added so... |
For example, an exothermic reaction will release energy to provide energy to overcome the activation energy. So, why doesn't the enthalpy change affect the rate of reaction? |
Why doesn't the enthalpy change of a reaction affect the rate of reaction? |
Why doesn't carbon forms bonds with itself to form a molecule? Carbon shows the property of catenation, so why doesn't it form a cyclic molecule such as:
C = C
‖ ‖
C = C |
I remember in my first chemistry lessons at high school my teacher told us about atomic properties of materials elastics and stiffness and what ever else. At one point he came up with an example of a (theoretical?) liquid that would even crawl out of its vessel to overcome differences in gravity, *desiring* to get to a... |
> 1. How would you deal with a user who produced a steady stream of valuable answers, but tends to generate a large number of arguments/flags from comments?
I would look into what caused the flags and arguments. Many flags on this forum are for outdated posts and we have a pretty wholesome community. However, if the... |
I am planning to electrolyze water for an experiment. However, I have limited resources and want to do it as safely as possible
>The resources that I have:
>
> - $\pu{12 V}$ DC battery
> - Graphite (in the form of a pencil lead)
> - Stainless Steel
> - Alligator lead clips
> - Sodium Hydroxide ($\ce{... |
> 1. How would you deal with a user who produced a steady stream of valuable answers, but tends to generate a large number of arguments/flags from comments?
I would look into what caused the flags and arguments. Many flags on this forum are for outdated posts and we have a pretty wholesome community. However, if the... |
The image below shows a [3,3] sigmatropic rearrangement. My question is why does the increased temperature favour the right side? The arrangement is technically the same except for the methyl groups on different carbons.
[![enter image description here][1]][1]
Here is another example:
[. Are they alluding to Freezing Point Depression? Are they correct?
> **Pour 3 tbsp (51 g) of salt into each of your 3 plastic water bottles.** Use disposable plastic bottles for the e... |
Ought I add salt to water bottles, if I'm putting the bottles in front of a fan to improvise an air conditioner? |
1. Is [this advice](https://www.wikihow.com/Make-an-Easy-Homemade-Air-Conditioner-from-a-Fan-and-Water-Bottles) correct? Are they alluding to Freezing Point Depression? Adding salt to tap water lowers the [Crystalloid](https://www.easybiologyclass.com/difference-between-colloids-and-crystalloids-a-comparison-table/)'s ... |
I have performed a gaussian16 calculation to explore the size-consistency problem for the CISD and CCSD methods. The system I am studying is the water dimer and the results are not what I expected at first. I have computed the energy of the dimer for both models (single point calculation) and the energy of the "dimer" ... |
Why doesn't carbon form bonds with itself to form a molecule? Carbon shows the property of catenation, so why doesn't it form a cyclic molecule such as:
C = C
‖ ‖
C = C |
I have performed a Gaussian16 calculation to explore the size-consistency problem for the CISD and CCSD methods. The system I am studying is the water dimer and the results are not what I expected at first. I have computed the energy of the dimer for both models (single point calculation) and the energy of the "dimer" ... |
I have performed a Gaussian16 calculation to explore the size-consistency problem for the CISD and CCSD methods. The system I am studying is the water dimer and the results are not what I expected at first. I have computed the energy of the dimer for both models (single point calculation) where the two monomers are 100... |
How does the application of the Schrodinger equation to model system such as particle in a box help us understand the origin of the degeneracy of atomic orbitals?
This is a genuine question on a university level assignment. I am unable to find any answer online. Any help would be appreciated! |
Does anyone know where I can find some documentation of a real-world liquification process, and the energy costs?
I can calculate the heat that must be removed from O2 gas to get to liquid, but how would this translate to an electricity cost for cooling equipment? |
How much energy is required to liquify oxygen? |
While reading about Henry's law and solubility I frequently come across two relations:<br>
1) $C = k_{h}*P$
2) $P = k_{h}*x$
What is the difference in these two expressions, do they seem to contradict each other? I am not able to decide whether a gas with higher $k_{h}$ would be more soluble or less soluble.
Ple... |
Does 50% hydrogen peroxide dissolve gold? |
While reading about Henry's law and solubility I frequently come across two relations:<br>
1) $C = k_{h}P$ (c = concentration of a dissolved gas)
2) $P = k_{h}x$ (x = solubility/mole_fraction)
What is the difference in these two expressions, do they seem to contradict each other? I am not able to decide whether a ... |
I have performed a Gaussian16 calculation to explore the size-consistency problem for the CISD and CCSD methods. The system I am studying is the water dimer and the results are not what I expected at first. I have computed the energy of the dimer for both models (single point calculation) where the two monomers are 100... |
What is left over when water and sodium hypochorate decompose, i.e. household bleach? |
> Which is more stable?
>
> 1. $\ce{^+C(CH3)3}$
> 2. $\ce{^+C(CD3)3}$
I have read in Solomon's and Fryhle that the +I effect of D is more than that of H but here in this problem it is given that $\ce{(CH3)3C+}$ is more stable.
How is this possible? Since, deuterium enriches the electron density over the cent... |
This must be a very basic question but I have gotten confused over it.
How would I find the concentration of each component of the reaction for each experiment from this data? I am guessing it can’t be the concentrations given, is that for some stock solution? [![enter image description here][1]][1]
[1]: https... |
In class we are looking at Tanabe-Sugano diagrams, more concretely at transitions for a d<sup>2</sup> complex. [![d2 tanabe-sugano diagram][1]][1]
I understand that the only spin allowed transitions are those that have a triplet state, therefore that there are 3 spin allowed transitions
<sup>3</sup>T<sub>1g</su... |
I have searched the web all over this question and I have not really found an answer to my satisfaction. From my understanding of the topic so far, I understand that reason why concept of unified atomic mass works better than providing absolute mass of protons/neutrons (in grams or kilograms) is because "u" provides be... |
Why is atomic mass unit/unified atomic mass defined against Carbon 12? |
How does temperature and other factors affect sigmatropic rearrangements? |
So I'm learning about Lewis structures for university. I was reading a book written by some teachers from my university and in one exercise they ask us to draw the Lewis structure for potassium permanganate ($KMnO4$). I attempted to do it, but when I compared my answer to that of the book I realized what I did was wron... |
Are acid anhydride and anhydride the same thing? |
Is there a link between where the functional group is located in an organic compound and the compound's heat of combustion? [It has been mentioned before][1] that it is difficult to accurately get the enthalpy of a reaction experimentally; thus, enthalpies of formation are used instead when calculating it.This is why I... |
Does the position of a functional group in an organic compound have any effect on the compound's heat of combustion? |
Is it possible for the ring junction to be trans in a molecule containing 2 fused cyclopentane rings? I am aware it is not possible for fused cyclobutane rings but am not sure about the 5-membered counterpart. In case the question isn't clear, the ring junction I am referring to is the one that has stereochemistry draw... |
How does the application of the [Schrödinger equation][1] to model a system, such as a particle in a box, help us understand the origin of the degeneracy of atomic orbitals?
[1]: https://en.wikipedia.org/wiki/Schr%C3%B6dinger_equation
|
This must be a very basic question but I have gotten confused over it.
How would I find the concentration of each component of the reaction for each experiment from this data? I am guessing it can’t be the concentrations given, is that for some stock solution?
[![enter image description here][1]][1]
[1]: htt... |
How to avoid explosion when there is a leakage of LPG gas and coal gas/town gas? What are the conditions of that happening? The related underlying chemical reactions are hydrogen and butane combustion in oxygen, right? What is the reaction mechanism? We should avoid using any electrical appliances, electric light, elec... |
How to avoid explosion when there is a leakage of LPG gas and coal gas/town gas? |
Is there a link between where the functional group is located in an organic compound and the compound's heat of combustion? [It has been mentioned before][1] that it is difficult to accurately get the enthalpy of a reaction experimentally; thus, enthalpies of formation are used instead when calculating it.This is why I... |
I have done Hartree-Fock calculations on a single He atom and now I tried to check numerically if the electron density fulfills the [Kato theorem](https://en.wikipedia.org/wiki/Kato_theorem). It apparently doesn't. Instead I obtain a cusp corresponding to an effective charge of about $1.76$. That looks suspiciously lik... |
Do Hartree-Fock (or other model Hamiltonian) electron densities fullfill the Kato theorem? |
Is there a link between where the functional group is located in an organic compound and the compound's heat of combustion? [It has been mentioned before][1] that it is difficult to accurately get the enthalpy of a reaction experimentally; thus, enthalpies of formation are used instead when calculating it.This is why I... |
$$KCl+KMnO_4+H_2SO_4\rightarrow K_2SO_4+MnSO_4+H_20+Cl_2$$
**Attempt.** I want to adjust this redox reaction, I've figured out that Chlorine and Manganese are the 2 elements that change thier oxidation number. But I've encountered the problem that if I do: $$KCl\rightarrow\frac12 Cl_2$$ I don't have any ideas on how t... |
$$KCl+KMnO_4+H_2SO_4\rightarrow K_2SO_4+MnSO_4+H_2O+Cl_2$$
**Attempt.** I want to adjust this redox reaction, I've figured out that Chlorine and Manganese are the 2 elements that change thier oxidation number. But I've encountered the problem that if I do: $$KCl\rightarrow\frac12 Cl_2$$ I don't have any ideas on how t... |
So during the course of my research, I've read countless papers related to the hydrogenation of dibenzyltoluenen and the dehydrogenation of perhydro-dibenzyltoluene. Now what I've noticed, is the fact that I could not find any data concerning the kinetic models linked to this hydrogenation process (I did find kinetic d... |
What kinetic model does the hydrogenation reaction of dibenzyltoluene follow? |
I am playing around with basis set extrapolations, and i would like to perform some simple tests by doing some parameter fitting and checking the errors.
The functional form of the fitted curve is this
$$
E(X) = E_\infty + Ae^{-\alpha X}
$$
where $X$ is the cardinal number of the basis set used, and $E$ is t... |
What is the proof of Kohlrausch's Law of Independent Migration of Ions? How did Kohlrausch calculate the limiting molar conductance of a weak electrolyte? I am asking this in context of electrochemistry and limiting molar conductance of a weak electrolyte. |
I found a discrepancy between a [government-approved][1] [procedure][2] of living quarters demercuration and the [patent][3] RU 2081198 C1 the procedure is based on.
The last phase of cleaning involves fixing remaining mercury salts $\ce{HgI2}$, $\ce{Hg2I2}$, $\ce{Cu2Hg2I2}$ (I didn't find any mentions of $\ce{Cu2Hg... |
How to use Sodium Thiosulfate for for dicopper (i) tetraiodomercurate (ii) and mercury (ii) iodide fixing? |
How to use Sodium Thiosulfate for fixing dicopper (i) tetraiodomercurate (ii) and mercury (ii) iodide? |
I am a High School student and while reading about reactions on Amines, I was trying to figure out a way to convert Aniline ($C_6H_5NH_2$) to Phenol ($C_6H_5OH$) without diazotizing it with Sodium Nitrite ($NaNO_2$) and dilute Hydrochloric Acid ($HCl$) in temperature conditions of 273-278K and then reacting it with $H_... |
Is there a way to convert Aniline to Phenol without Diazotizing it? |
I was studying about oxidising flames and realized that sodium burns with a bright yellow flame the wavelength of which is around 588nm then I searched for emission spectra of sodium and found that the lines around 588nm are the most intense ones so it appears yellow. Same happened with potassium.
But when I arrived ... |
Why hydrogen burns with a pale blue flame while its emission spectral lines are red in colour? |
I am a High School student and while reading about reactions on Amines, I was trying to figure out a way to convert Aniline ($\ce{C_6H_5NH_2}$) to Phenol ($\ce{C_6H_5OH}$) without diazotizing it with Sodium Nitrite ($\ce{NaNO_2}$) and dilute Hydrochloric Acid ($\ce{HCl}$) in temperature conditions of 273-278K and then ... |
**DISCLAIMER**
**DO NOT TRY TO DEMERCURATE USING DESCRIBED PROCEDURE. CONSULT YOUR EMERGENCY SERVICE.**
----------
I found a discrepancy between a [government-approved][1] [procedure][2] of living quarters demercuration and the [patent][3] RU 2081198 C1 the procedure is based on.
The last phase of clean... |
How to use Sodium Thiosulfate for fixing dicopper (I) tetraiodomercurate (II) and mercury (II) iodide? |
I was studying about oxidising flames and realized that sodium burns with a bright yellow flame the wavelength of which is around 588 nm then I searched for emission spectra of sodium and found that the lines around 588 nm are the most intense ones so it appears yellow. Same happened with potassium.
But when I arriv... |
I was studying about oxidising flames and realized that sodium burns with a bright yellow flame the wavelength of which is around 588 nm then I searched for emission spectra of sodium and found that the lines around 588 nm are the most intense ones so it appears yellow. Same happened with potassium.
But when I arriv... |
I am a High School student and while reading about reactions on amines, I was trying to figure out a way to convert aniline ($\ce{C_6H_5NH_2}$) to phenol ($\ce{C_6H_5OH}$) without diazotizing it with sodium nitrite ($\ce{NaNO_2}$) and dilute hydrochloric acid ($\ce{HCl}$) in temperature conditions of 273-278K and then ... |
Is there a way to convert aniline to phenol without Diazotizing it? |
I am a high school student and while reading about reactions on amines, I was trying to figure out a way to convert aniline $(\ce{C6H5NH2})$ to phenol $(\ce{C6H5OH})$ without diazotizing it with sodium nitrite $(\ce{NaNO2})$ and dilute hydrochloric acid $(\ce{HCl})$ in temperature conditions of $\pu{273 K}$ to $\pu{278... |
Is there a way to convert aniline to phenol without diazotizing it? |
I am a high school student and while reading about reactions on amines, I was trying to figure out a way to convert aniline $(\ce{C6H5NH2})$ to phenol $(\ce{C6H5OH})$ without diazotizing it with sodium nitrite $(\ce{NaNO2})$ and dilute hydrochloric acid $(\ce{HCl})$ in temperature conditions of $\pu{273 K}$ to $\pu{278... |
Can guanidine or guanidinium ion give stable N-Nitrosamines at pH > 7 and < 100 °C?
It is a resonance system, and the nitroso group could be also stabilized by resonance therefore. |
Can guanidine or guanidinium ion give stable N-Nitrosamines at pH > 7 and < 100 °C? |
Can oxidizing agents be used to increase the combustion efficiency of waste oil? |
>Can guanidine or guanidinium ion give stable *N*-nitrosamines at $\mathrm{pH \gt 7}$ and temperature $\lt \pu{100 ^\circ C}$?
It is a resonance system, and the nitroso group could be also stabilized by resonance therefore. |
Can guanidine or guanidinium ion give stable N-nitrosamines at basic conditions below 100 °C? |
You have to convert the SMILES to a graph model. Most everything you want to do with SMILES requires you construct the graph model, i.e., nodes (atoms) and arcs (bonds). Once you have that, you can go through all nodes, and see how many of their sites are occupied by explicit bonds, the rest you hydrogenize.
If you ... |
>Can the guanidinium ion react with NO donors to stable *N*-nitrosamines at $\mathrm{pH \gt 7}$ and temperature $\lt \pu{100 ^\circ C}$?
It's a resonance system, and the nitroso group could be also stabilized by resonance therefore. |
Can the guanidinium ion give stable N-nitrosamines at basic conditions below 100 °C? |
It is safer to keep the process as simple as possible _without_ the addition of perchlorates or peroxides to the oil. Perchlorates are salts with low solubility in oil; hydrogen peroxide equally is a polar compound with little affinity to form a solution with oil. Thus, the salts could clog the fuel delivery, or in c... |
By definition, *N*-nitrosamines are aliphatic or aromatic derivatives of secondary amines, which have a nitroso group ($\ce{–NO}$) attached to nitrogen. In general, *N*-nitroso compounds are usually formed by the interaction of a nitrosating agent ($\ce{NOX}$) derived from either nitrite salts or nitrogen oxides with a... |
Apparently the discussion does not go much ahead. So I will try to speed it up and show how it goes. First try to establish the half-reaction with ions, not with formula units. We will take care of the molecules and formula units later on. Here, in the first half-reaction, the ion $\ce{MnO4-}$ is reduced to $\ce{Mn^{2+... |
Apparently the discussion does not go much ahead. So I will try to speed it up and show how it goes. First try to establish the half-reaction with ions, not with molecules and formula units. We will go back to neutral compounds later on and get rid of the positive and negative charges at the end.
Here, in the first... |
$$\ce{KCl + KMnO4 + H2SO4 -> K2SO4 + MnSO4 + H2O + Cl2}$$
**Attempt.** I want to adjust this redox reaction, I've figured out that Chlorine and Manganese are the 2 elements that change thier oxidation number. But I've encountered the problem that if I do:
$$\ce{KCl -> 1/2 Cl2}$$
I don't have any ideas on how ... |
Can the guanidinium ion give stable N-nitrosamines under basic conditions below 100 °C? |
I am preparing notes on buffers and I came across this problem on a website:
> Given 10.0 mmol of a weak acid HA with $\textrm{p}K_a$ of 5, how many mmol of NaA needs to be added to have a final $\textrm{p}H = 5$?
The solution method shown used the Henderson-Hasselbalch equation
$$\textrm{p}H = \textrm{p}K_a +... |
Background - In a laboratory setting, I use typical elemental analysis (EA) to generate about 50 µg of sulfur in the form of sulfur dioxide (SO<sub>2</sub>). The EA uses a helium carrier. As an example, a sample of silver sulfide wrapped in tin falls into the reactor set to 1000 °C at the same time as an oxyg... |
As asked in the title, would the various salts -such as hydrochloride or methyl iodide- of V-Agents interact any differently with acetylcholinesterase compared to the neutral compound? For instance, would the interactions between [33-SN][1] and AChE differ in any way from those between [33-SN+][2] and AChE? Also, would... |
Do phosphoryl thiocholines, their uncharged analogs, and other organophosphates, interact differently with Acetylcholinesterase? |
[![enter image description here][1]][1] [![enter image description here][2]][2]
[1]: https://i.stack.imgur.com/ZZB1Q.png
[2]: https://i.stack.imgur.com/Sw5sI.png
---
I initially approached it like this:
As both are allylic carbocations, and that both are in fact resonating structures of the same... |
Which of the following structures would be least stable? |
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