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16

Overview The only interesting thing about lactones is that if the ring size is relatively small, they necessarily adopt the (E) conformation. Therefore, the question essentially boils down to: for a generic ester, why is the (E)-conformer 1 more acidic than the (Z)-conformer 2? This is a question that is easier to investigate, since we remove all other ...


16

Dissenter is correct about aromatic compounds and that the basic requirement for a compound to be detected by smell is for it to be volatile enough to reach the nose. This is why things like dry salt don't really smell like anything. Once they reach the nose, things become more complex. Why many esters smell fruity while most thiols smell rather unpleasant ...


15

The term "Essigäther" is actually the German name for ethyl acetate i.e Essig = "vinegar" + Äther = "ether". "vinegar" becomes acetic, hence ethyl acetate becomes "acetic ether". (etymoline.com) But, ethyl acetate is an ester. So, why is it named "acetic ether"? According to Leopold Gmelin, ester ...


11

Yes, it is possible. One reagent to do so is acidic bromate salts. This paper discusses a number of optimizations and characterizations of the bromate-powered ether oxidation reaction. $$\ce{R-CH2-O-CH2-R + BrO3- ->[H+][H2O; {r.t.}] R-CO-O-CH2-R + Br^-}$$ Hydrolysis of the formed ester leads to an undesired byproduct: the free acid $\ce{RCOOH}$. In ...


11

Surely the negatively charged oxygen would protonate before the other oxygen would. Most of the time, but not all of the time. The amine group is more basic than the "alcohol group" that must leave to form the amide so why wouldn't that protonate first and then just leave (i.e no reaction)? Most of the time, but not all of the time. Your ...


10

Some hard data: bond enthalpies (in $\pu{kJ mol-1}$) $$\begin{array}{c|c|c|c} \text{Bond} & \text{Enthalpy} & \text{Bond} & \text{Enthalpy} \\ \hline \ce{C-C} & 350 & \ce{Si-Si} & 226\\ \ce{N-N} & 163 & \ce{P-P} & 201\\ \ce{O-O} & 146 & \ce{S-S} & 226\\ \ce{F-F} & 155 & \ce{Cl-Cl} & 240 \\ \...


9

Understanding how this reaction is actually performed in the lab is key to answering your question. Typically in the malonic ester synthesis, a full equivalent (or 2 equivalents if you are carrying out a dialkylation) of base is used, so little, if any, ester remains with the $\ce{\alpha}$-proton still in place. (image source) Also, keep in mind that both ...


9

In the typical reaction of hydroxide ion with a methyl ester, the hydroxide attacks the carbonyl carbon of the ester, resulting ultimately in elimination of methoxide. Given the basic conditions, the carboxylic acid formed immediately deprotonates to a carboxylate, and the methoxide is protonated to methanol. In older texts particularly, this reaction ...


8

The term aromaticity originated with the discovery of unusually stable hydrocarbons that also happened to have strong smells. Many hydrocarbons smell, but not all are aromatic. Nowadays, a compound being classified as "aromatic" has little to nothing to do with its smell and everything to do with its electron configuration. There are also non-aromatic ...


8

Double alkylations of the $\ce{CH2}$ centre of malonic esters do work! Have a look at this marvel by R. P. Mariella and R. Raube, published in Org. Synth., 1953, 33, 23 EDIT 1 The use of sodium metal in a properly dried alkanol (in the case of ethanol, refluxing over magnesium ribbon is a good choice) was (and still is) an excellent and cheap method to ...


8

The first four steps (i.e. the main reaction) are conducted under basic conditions due to the presence of alkoxide. When that reaction is complete, the result is the deprotonated ketoester--the formation of that stable species is what drives the reaction to completion. Note that the first 3 steps are shown as equilibria, whereas the fourth step is ...


7

The IUPAC recommends s-cis and s-trans for the rotamers of conjugated dienes. The nomenclature derives from having a "cis-like" or "trans-like" geometry about a sigma bond. I feel like something similar should be appropriate, however that same IUPAC link recommends E/Z or sp/ap (syn-periplanar/anti-periplanar) for the N-alkyl amides (5,6). Amide 5 ...


7

A methyl cation definitely won’t leave by itself. However, you can consider bromide ions floating around in solution. These bromide, being nucleophilic can attack the methyl group in an $\mathrm{S_N2}$ manner, because any positively charged oxygen is a good leaving group. Therefore, the side product would be bromomethane. Other than that, your mechanism is ...


7

Prediction software always has its limitations, and there is always a degree of error in the calculation. For the ChemDraw predictions, you will see that for the 3 aromatic environments, it has done 3 independent calculations, and has happened to arrive at the same chemical shift. This simply means that these shifts are coincident, not equivalent. Remember, ...


7

To answer this,Think about how an ester is formed. In the formation of an ester, wherin you react an alcohol with an acid in presence of conc.$\ce{H2SO4}$ $\ce{RCOOH + R'OH -> RCOOR' + H2O}$ Now what we have found by replacing the oxygen with an isotope of oxygen is that $\ce{RCOO'H + R''OH -> RCOOR'' + H2O'}$ What this reveals is that the acid ...


7

The esterification is not the only thing catalysed by sulphuric acid. Basically, it’s catalytic activity is protonation of whatever feels happy enough to be protonated. In your desired esterification mechanism, we want to protonate the acid: $$\ce{R-C(=O)-OH + H2SO4 <=> R-C(=\overset{+}{O}H)-OH + HSO4-}\tag{1}$$ This will ease the nucleophilic attack ...


7

Amide analogue of lactons are lactams, their tautomeric forms are lactims. Citing from the IUPAC Nomenclature of Organic Chemistry (Preferred names 2013): P-66.1.5.1 Lactams and lactims Intramolecular amides of amino carboxylic acids, $\ce{-CO-NH\bond{-}}$, are called ‘lactams’ and their tautomers, $\ce{-C(OH)=N\bond{-}}$, are ‘lactims’. Lactams ...


7

Dimethyl acetamide (DMA) is less susceptible to hydrolysis than ethyl acetate (EA). This statement is true for aqueous acid or base. The infrared (IR) frequency for the carbonyl group of DMA is 1662 cm-1 while EA is 1742 cm-1. The lower the frequency, the lower the energy and the more, relatively speaking, single bond character in the carbonyl group. Thus, ...


6

You are getting too specific as though these are biological processes. They do not have to be... ANY ester made is an esterification reaction. So any ester can be transesterified into a different alkyl alkanoate and any carboxylic acid or derivative (even nitriles) can be esterified. See the diagram:


6

Try to understand it in a layman's way, greater the extent of overlap between the atoms, the closer their nucleus will be. The stability of the molecule will thus increase as stability of a molecule is inversely proportional to the bond length of the atoms in the molecule. However this is applicable only upto some extent like your situation but if the ...


6

It's unnecessary. In the reaction you are suggesting, the enolate would have to attack the carbonyl double bond from above. The optimum angle of attack is roughly $107^\circ$ but since both the attacking enolate and the diester substrate are reasonably bulky, there I suspect there will be a considerable amount of steric hindrance here, creating a large ...


6

Option 2 generally gives higher yields. This is because option 1 (Fischer esterification) usually results in an equilibrium mixture which contains significant amounts of products and reactants, limiting the yield. This is mitigated by using a stoichiometric amount of a concentrated acid catalyst, such as sulfuric acid, which is also a strong dehydrating ...


6

I doubt your book is asking you to convert this molecule into a lactone. This would be very hard to do. It could, however, be easily converted into a lactam. 5 and 6 membered lactams are formed by simple dehydration. For your γ-lactam, this can be achieved by heating the amino carboxylic acid, forming the thermodynamically favourable, stable 6-membered ...


6

The key to this synthesis should be — in my opinion — how to generate the two hydroxy functions with anti stereoselectivity starting from at least one achiral reagent. Most of the time you would attempt building up chirality de novo using chiral auxiliaries, catalysts or reagents as these methods are often more cost-efficient than acquiring a specific chiral ...


6

Just to add another resource besides the excellent find by Nilay, in Organic Chemistry, The Name Game, it mentions ester from German Essigäther (acetic ether) an early name for ethyl acetate The unabridged Oxford English Dictionary (by subscription only) also mentions that Gmelin called these compounds as napthas but later he changed it to ester. H. Watts ...


5

The biodiesel process should work well, you will need just slightly more aggressive conditions (i.e. slightly more catalyst, slightly higher EtOH excess, and/or slightly longer time) to make ethyl esters instead of methyl esters, as ethanol is slightly less reactive than methanol. For skin care, you will need higher purity than biodiesel processes usually ...


5

Both methods are used in practice (and a a lot more exist). Diazomethane is a last resort method when everything else fails. For example you might have a molecule that is acid sensitive or heat sensitive and then $\ce {MeOH/H^+}$ is out of the question. Although diazomethane is an excellent reagent to do the job, as it works selectively with almost every ...


5

Reaction of a Grignard reagent with an ester is a standard method for producing tertiary alcohols where at least two of the substituents (the "$\small\ce{R_2}$" group attached to the Grignard) are the same. Judicious choice of the starting ester allows for the preparation of a tertiary alcohol where all 3 substituents are the same. Alternately, you could ...


5

Traditional malonic ester synthesis post-processing includes hot acidic hydrolysis, which should lead to substituted malonic acid. However, such acids are prone to decarboxylation, leading to tertiary carbon. In case you deviate from the tradition, there is no problem with getting quaternary carbon (though general bulkiness still applies and may prevent ...


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