New answers tagged

2

You raise the examples of isonitriles and nitriles undergoing C–N bond cleavage via hydrolysis. That is true, but it is worth thinking about how this happens. Both isonitriles and nitriles are converted to amides first when reacted with aqueous acid. Now, amides will certainly be hydrolysed at the last stage of the peptide sequencing: you can see that in the ...


1

What you should be looking at is the stability of the carbocation intermediate formed when the strong acid $\ce{HBr}$ protonates the alkene. This stability is more sensitive to alkyl substitution than the stability of the uncharged alkene, so the net effect is that alkyl substitution lowers the activation energy versus having no substitution. Ergo a faster ...


0

I suspect you'll get a much better answer if you migrate this question to biology SE, but here's what I've done: add your chosen volume of nuclease-free TE buffer or water (assuming the DNA is precipitated with salts). Leave it in the fridge (~4 C) overnight to allow for slow hydration. Gently resuspend the DNA by very slowly pipetting the solution up and ...


0

The methyl group carbon has a partial negative charge due to the polarity present in the C-H bonds. This partial negative charge is preferentially donated, leading the methyl group to have the +I effect. An important way to consider the stability of a tertiary carbocation is through the process of hyperconjugation. Neighboring C-H or C-C bonds, parallel to ...


4

Friedel–Crafts reactions proceed through the alkylation or acylation of an aromatic ring using an alkyl halide. Considering the alkyl halide compound of the form $$\ce{R-X}$$ where $\ce{R}$ is the alkyl group and $\ce{X}$ is the halide (whatever it may be), I assume the question is asking what compound, of the previously noted form, could be added to an ...


2

Baker (J. Chem. Soc., 1678 (1934)) describes the condensation of catechol with acetone and it went down another path. Indeed the acetone self-condensation interferes with your reaction plan: acetone self-condensation eventually leads to phorone, which condensed with two molecules of catechol to form "5:6:5':6'-tetrahydroxy-3:3:3':3'-tetramethylbis-1:1'-...


0

For answering the question, it makes sense to look at the definition of the term polymer as recommended by the International Union of Pure and Applied Chemistry (IUPAC) that they give in their Gold Book. It says a polymer is... A substance composed of macromolecules. So the word polymer does not refer to individual molecules although it is colloquially ...


1

I refer to a good response on the general question "Discrete variables in regression model? found on a sister site. The quote in part: General confusion appears when you mix in ordinal data, such as those 5-point "how satisfied are you?" questions. They are expressed in whole number, very easily to be confused with discrete data. However, ...


1

This answer will give you little insight about chemistry, and maybe a little insight into problem solving strategies. The primary carbon atoms are easy to solve, we must link them to a single bond, but how about the other ones? This is a good insight. The entire structure has 9 carbons and 14 hydrogens. To simplify it, we can replace the 5 methyl groups by ...


3

I'm not sure why you think they are enantiomers. They are actuallually diastereomers as stated: As depicted, the compound to the left is $(2R,3S)$- while the compound to the right is $(2R,3R)$-. Thus, they are pair of diastereomers. To be enantiomers, either the compound to the left should be $(2S,3S)$- or the compound to the right should be $(2S,3R)$-.


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What is important in a mechanism is the collision factor and the activation energy. A high energy intermediate can help study the activation energy because the TRANSITION state will have similar molecular construction to the intermediate and factors stabilizing the intermediate might be important in lowering the activation energy. I am not familiar with NBS ...


2

There is no cure-all solution for descaling and no "reaction" because scale is not a standard compound. Its composition will vary with water quality. So it is a bad idea by these companies to spread rumors that citric acid passivates limescale. One has to know what the scale is and the construction material, to begin with descaling. I think it all ...


3

The question you pose is the work of Stork and Dolfini that led to the synthesis of aspidospermine 7 and quebrachamine 9. The aminoketone 1a was condensed with either phenylhydrazine or o-methoxyphenylhydrazine to form the respective arylhydrazones 2a and 2b. Exposure of either hydrazone to hot acetic acid led to a "Fischer indole synthesis" that ...


-2

You can find the stronger acid by comparing the stability of their conjugate bases. 4-nitrophenol has the NO2 group (showing both electron withdrawing inductive and resonance effect) at the para position which will pull the electron pair away from the O- group. As you can see there is an additional resonance structure in its conjugate base giving it more ...


3

Fischer Indole for the first step looks possible depending on reaction conditions, but this source states that the indole nucleus is not reduced by LiAlH4, nor do I recall ever seeing it done. Therefore I think what is happening is formation of the phenylhydrazone followed by reduction to the 1,2 di-substituted hydrazine.


1

Perhaps the nitrogen next to the aromatic ring could attack the carbonyl group. However: The bulky phenyl group is closer to the reaction site, and thus causes more steric interference, than would be the case with the primary nitrogen attack. The nitrogen next to the phenyl ring conjugates its electron pair to the ring just as in a typical aromatic amine, ...


3

As noted earlier, the determining factor is the greater strength of the carbon-chlorine bond versus carbon-bromine, which leads to a higher activation energy for the magnesium to react with the former. The strength of a carbon-halogen bond, and therefore the activation energy required for magnesium to form a Grignard reagent, is greatest with fluorine and ...


1

The commonplace reaction of a ketone with a Grignard reagent involves the oxygen acting as a nucleophile ... towards the magnesium. The view from the other side Yes, the negatively polarized carbon gets all the headlines as a nucleophile, as this is the function that ends up in the alcohol that we identify as the product after workup. The magnesium literally ...


3

Reference [1], in the question, indicates that the phenyl group is not really special. In the gas phase substitution onto the nitrogen with either an alkali (methyl) group or an adult (phenyl) group increases basicity, and the effect is cumulative when multiple substitution is used. While this reference does not specifically address diphenylamine or ...


2

A plausible reaction leading to your product is the following reaction: i.e., a mixture of (R) and (S)-configurated product is formed. In the presence of $\ce{AlCl3}$, the alkylhalogenide becomes something like a carba cation, where you potentially loose stereogenic information (-> racemic mixture). In the work-up, the addition of water destroys [...


1

I used polyphosphoric acid and it worked.


1

The lye is the agent to push the hydrolysis of the peptide forward. The initial concentration of the lye may affect the rate of this digestion (temperature, pressure, time of residence of the reagents in the reactor are equally factors to be considered), as well if the digestion is exhaustive. As shown by the reaction scheme, the reaction yields water; ...


1

Normally, the tertiary alcohols do not react with potassium permanganate. However, you added a strong acid (H2SO4). So, the sulfuric acid can react with the alcohol, generating an alkene, and then the alkene could oxidize with potassium permanganate.


2

Indeed $\ce{C5H_{10}}$, specifically pent-1-ene, has been documented[1]: The pyrolysis of n-hexane has been investigated in the ranges 723–823 K and 10–100 Torr at up to 3% decomposition. The reaction is homogeneous and free from the self-inhibition by olefin products observed for several other alkanes. The products of the reaction are hydrogen, methane, ...


2

Cyanohydrins are formed under acid conditions in the presence of cyanide - essentially the addition of HCN across the C=O bond. Mechanism from Wikipedia Cyanohydrins are stable under acidic conditions, but note that the reactions are reversible. Under basic conditions (eg carbonate work up of the hydrolysis reaction) the reaction runs backwards losing ...


0

The answer involves considering the two main factor that dictates packing or anyway molecular interactions (don't call them bonds!) in alkenes in the two different states. These are the type of molecular interaction as well as the geometrical shape. As for the shape, cis-alkenes have a kind of U bent geometry. This interfere with packing as compared to the ...


1

Yes. TFA is widely used for alcohol dehydration, for example as described in this review. TFA is a standard reagent for the ionic hydrogenation of alcohols with hydrosilanes which proceeds via the protonation of the alcohol and the formation of the cation wikipedia article


1

The reaction between anhydride and primary amine is by the Nucleophic addition-elimination mechanism (NOT by SN2). First step: Nucleophilic addition step (Rate determining step): The addition of amine to carbonyl center (at the most electrophilic carbonyl center and it should generate least sterically hindered intermediate) gives rise to a tetrahedral ...


2

Simply put, an α-hydroxy acid does not have multiple functional groups on the same carbon atom. It has a carboxyl group centered on one carbon and an hydroxyl group on an adjacent carbon; the latter is the α in "α-hydroxy acid". If the additional hydroxyl group were two carbon atoms away would be a β-hydroxy acid, three carbons away would be a γ-...


2

You should not consider the two carbocations distinct. They are one and the same, the identical molecule. There will be a fractional positive charge observable on the tertiary carbon and a fractional positive charge observable on the secondary one. Looking at orbitals, there is just one LUMO (lowest unoccupied molecular orbital) which in first approximation ...


1

The inefficiency of soft, essentially pure, water for rinsing soap from skin is well recognized. However, a broader explanation includes the difficulty in removing the last traces of anything from anything else. I estimate that the wash liquid from bar soap results in about 2% soap, perhaps more. This concentration will reduce the surface tension of water ...


0

Your thought is correct, but the application not quite. You are correct, the resonance structures vary from secondary and tertiary carbocation, because the proton will attack the double bond at the end of the molecule to form the more stable carbocation, but: The more substituted alkene will be considerably more stable. The product you have drawn is ...


11

Unfortunately, your analytical question is not an easy one, and no test can be done safely at home or by using a handheld gadget. The problem is fluorine, and tiny amounts of it in the sample. Fluorine in organic compounds does readily not participate in analytical detection tests. A straightforward method for the qualitative detection of fluorine in organic ...


2

Drawing on the comments of @user55119 above, I am going to to summarise the comments as an answer. There is no way of selectively hydrolysing the acetanilide in the presence of the lactam. It doesn't matter because the lactam can be readily reformed from the completely hydrolysed material by treatment with a carbodiimide such as 1-(3-Dimethylaminopropyl)-3-...


2

$\ce{LiAlH4}$ is not formed by $6$ independent ions. But, for the present purpose, it reacts as if it was formed of $\ce{Li^+ + Al^{3+} + 4 H^-}$. The ions $\ce{Li+}$ and $\ce{Al^{3+}}$ do not react with water. The only ion reacting with water is the hydride ion $\ce{H^-}$, and the equation is $$\ce{H^- + H2O -> OH- + 1/2 H2}$$ As each $\ce{LiAlH4}$ &...


3

The most important simplified criteria for the choice of a principal chain are: greater number of substituents corresponding to the suffix (principal characteristic group) longest chain greater number of multiple bonds lower locants for suffixes lower locants for multiple bonds greater number of prefixes lower locants for prefixes lower locants for ...


0

This is correct. Since the methyl rearrangement can occur at either side of the planar carbocation, and Cl- can attack either side of the resulting planar tertiary carbocation, all four possible diastereomers are formed with equal preference. Here, you don't need to consider 1,3-diaxial interactions of cyclohexane either since the reaction occurs at carbons ...


0

Cross-linking of polymers reduces the chain length between the links and higher the cross-linking lower the length of these segments this consequently reduces the freedom of chains to rotate, fluctuate and translate converting it to be more rigid.The concept of melting for such structures may not be applicable and it is true that cross-linked polymers do not ...


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