Questions tagged [alcohols]

For questions about saturated and unsaturated alcohols, their physical properties, their reactions, etc. For questions about phenol, use the [phenols] tag instead.

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15
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2answers
69k views

Reaction of alcohols with PCl5 and PCl3

The reaction of alcohols $\ce{ ROH }$ with $\ce{ PCl5 }$ and $\ce{ PCl3 }$ yields an alkyl halide $\ce{RCl}.$ With $\ce{ PCl5 }$, the reaction is quite simple leading to the formation of $\ce{ RCl }$ ...
12
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3answers
28k views

Migratory aptitude in pinacol-pinacolone rearrangement

I am confused about the migratory aptitude of various groups, as there are many different orders for the same given in different places, especially about -Ph and -H. I would like to know if someone ...
13
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4answers
6k views

Why can't alcohols form hydrogen-bonded dimers like carboxylic acids?

Carboxylic acids such as acetic acid are capable of forming dimers: I'm wondering why alcohols like ethanol don't generally form dimers. In the diagram below, the oxygen atom on the left ethanol ...
12
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2answers
1k views

How do I predict the solubility of a compound in a mixture of water and an organic co-solvent?

I'm trying to predict the solubility of long alcohols (e.g. 1-octanol, 1-decanol or 1-dodecanol) in a mixture of water and an organic co-solvent such as DMSO, acetonitrile or ethyl acetate. For ...
9
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1answer
2k views

Is methanol really more acidic than water?

The question Why is methanol more acidic than water? deals with the reasoning of why methanol is more acidic than water. However, as mentioned in the comments of that question, the acidity constant of ...
4
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1answer
8k views

Mechanism for oxidation of primary alcohols to carboxylic acids

My teacher told me that the following is the mechanism for oxidation of primary alcohols to carboxylic acids: I've searched in books and online and didn't find a similar mechanism. For example, in ...
12
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2answers
34k views

Reactions of alcohol with sulfuric acid

I knew two chemical reactions of alcohol with sulfuric acid $\ce{CH3CH2OH + H2SO4 -> CH2CH2}$ Here product is having a double bond (ethene) and this reaction happens at 443 K temperature. $\ce{...
40
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1answer
82k views

Differences between phenols and alcohols

I know phenols are more acidic as compared to alcohols, but are they considered different from alcohols? Sure, you can study something as a subset, but are phenols considered a subset of alcohols, or ...
7
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4answers
10k views

Why don't alcohols undergo nucleophilic substitution with ammonia?

Alcohols can undergo nucleophilic substitution with $\ce{PCl5, POCl3, HCl}$. Halogenoalkanes can undergo nucleophilic substitution with $\ce{NH3}$. The $\ce{C-O}$ (in alcohol) and $\ce{C-Cl}$ (in ...
7
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5answers
26k views

How does the inductive effect, explain the reactivity of tertiary alcohols with halogen acids?

The reactions of primary and secondary alcohols with halogen acids ($\ce{HX}$, where $\ce{X}$=halogen) require the presence of a catalyst, $\ce{ZnCl_2}$. With tertiary alcohols, the reaction is ...
14
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1answer
728 views

Can we synthesize alcohols by the photolysis of hydrogen peroxide?

As I was going through my revision of organic chemistry, I came across free radical substitution of alkanes with halogens. In a similar process where we use hydrogen peroxide, instead of chlorine, so ...
10
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3answers
7k views

Why do tosylation and mesylation of alcohols follow different mechanisms?

Why do the tosylation and mesylation of an alcohol proceed via different mechanisms? More specifically, In tosylation, the lone pair of the alcohol attacks the sulfur in TsCl, but why does it not ...
5
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1answer
1k views

Phenol or ethanol as a nucleophile for ether formation?

If we react phenol with $\ce{C2H5I}$ in $\ce{C2H5O- Na+}$ (excess), $\ce{C2H5OH}$ (anhydrous) solutions . In this reaction why is diethyl ether not formed and the actual product is phenyl ethyl ...
4
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2answers
2k views

What is the OH in alcohol?

What is the $\ce{OH}$ functional group in alcohol (ethanol)? My teacher told me it isn't the same as the $\ce{OH-}$ ion or hydroxide. But it does donate one electron to the respective carbon chain and ...
13
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4answers
13k views

Why do hydroxyl groups only produce a singlet in proton NMR?

Take, for example, methanol ($\ce{CH3OH}$). The hydroxyl proton ($\ce{-O$\color{red}{\ce{H}}$}$) is three bonds away from three more protons ($\ce{-C$\color{blue}{\ce{H}}$_3}$), which aren't ...
6
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1answer
2k views

Saturation of multiple solutes

Can a liquid which is saturated with a single solute, dissolve a different solute, or is saturation a universal thing? I ask because I’ve seen that different solutes have different points (amounts) at ...
1
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1answer
680 views

What is more important, to have the parent chain be the cycle or the chain that has an hydroxyl group

I know how to name alcohols, I just don't know what I should chose as the parent chain. Should I chose the cycle or the chain with the hydroxyl group. Here is an example: My current algorithm tells ...
-2
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1answer
96 views

Rearrangement of 8a-ethyl-1,3,4,8a-tetrahydronaphthalen-4a(2H)-ol [closed]

really sorry for that previous post. I was actually half-asleep when I posted that q, hence the q was unclear. I am again reposting that question The answer is given as A. Can anyone please explain ...
5
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1answer
4k views

Ring contraction in pinacol rearrangement of cyclohexane-1,2-diol

I came across this question in three different textbooks. The question was: What is the major product obtained on dehydration (treatment with concentrated $\ce{H2SO4}$) of cyclohexane-1,2-diol. I ...
11
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1answer
239 views

Which electronic effects are responsible for the reduction of nucleophilicity of a hydroxy group orthogonal to an ester?

I am facing a similar synthetic problem as Boekman Jr. et al noted in their synthesis of Tetronolide.[1] I will quote their’s rather than disclosing my actual synthetic problem, but note that the key ...
11
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1answer
12k views

Reaction of secondary alcohol with ammoniacal silver nitrate (Tollens' reagent)

What are the products of the reaction of 2-butanol with silver nitrate? For the moment, I am a bit stumped as I only have $\ce{AgNO3}$ as an oxidizing agent to form a carboxylic acid from an aldehyde....
9
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1answer
2k views

How could alcohol be made into a powder?

In the news recently is 'Palcohol', powdered alcohol, that you add to water or existing liquids to make it alcohol. Presumably this would dissolve and break apart into alcohol and {some other compound}...
7
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2answers
907 views

Why does formaldehyde exist primarily as the gem-diol in aqueous solution?

From Wikipedia, Methanediol is the product of the hydration of formaldehyde $\ce{H2C=O}$, and predominates in water solution: the equilibrium constant being about $10^3$ and in a 5% by weight ...
4
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1answer
619 views

Why doesn't the oxidation of cellulose oxidise all the alcohol groups, and how does it cause discolouration?

In cellulose, there are several alcohol groups - the two on the ring being secondary alcohols, and the one on the branch being a primary alcohol. I would expect all of these to be oxidised in the ...
4
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1answer
5k views

Why are 1,3-diols protected with aldehydes but 1,2-diols are protected with ketones?

1,3 diols are usually reacted with benzaldehyde when protection of the OH groups is desirable, but acetone is used when the relation between the hydroxyl groups is 1,2. Why is it so?
2
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1answer
3k views

How can aqueous KOH give alcohol by SN2 of alkyl halide?

I ask this because SN2 requires a strong nucleophile, and I have read $\ce{OH-}$ isn't a strong nucleophile in a polar protic solvent like water. So, how can $\ce{OH-}$ replace, say $\ce{I-}$ from $\...
2
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1answer
1k views

Why is water more acidic than alkanols?

Why is $\ce{H-OH}$ more acidic than $\ce{CH3CH2-OH}$? A common answer to this question is because of the $+I$-effect of $\ce{CH3}$ the negative charge at $\ce{O}$ increases making it less acidic. But ...
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2answers
4k views

Why alcohol is volatile although it has hydrogen bonds?

We are always told that hydrogen bonds increase the boiling point of a liquid and as a result they decrease the liquid's volatility. I want to know the reason why, alcohol with hydrogen bonds is ...
11
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1answer
2k views

Why is the melting point of tert-butyl alcohol 140 °C higher than that of sec-butyl alcohol?

This is one of the most drastic differences in a physical property I've ever seen for two such similar molecules, and in a simplistic sense anyway the difference lies in the opposite direction from ...
10
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3answers
254 views

Have “molecular clusters” for azeotropes been identified?

A different question about azeotropes got me thinking about this point again. Azeotropes have a very specific composition so it seems that the azeotrope ought to have some sort of physical structure. ...
8
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2answers
13k views

Why is thionyl chloride preferred for preparing alkyl chlorides from alcohols?

Why is thionyl chloride ($\ce{SOCl2}$) preferred for preparing alkyl chlorides from alcohols, as opposed to say $\ce{PCl5}$ or $\ce{PCl3}$ ?
7
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2answers
2k views

How does SO2Cl2 react with alcohols?

Is the mechanism similar to the reaction of $\ce{SOCl2}$ with alcohols? If not, then how is it different? We have been taught about the latter at school but my friend quizzed me about $\ce{SO2Cl2}$. ...
7
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1answer
477 views

Mechanism for bromoetherification of olefinic alcohol

Propose a mechanism for the following reaction showing the relevant stereochemistry of intermediates and the final product. I am confused as to what is going on here. I guess there's some sort ...
6
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1answer
2k views

Electrolysis of Beer

Electrolysis of water, means that the water is separated into hydrogen and oxygen. As beer also includes water, I initially thought electrolysis of beer would cause the water to separate, and the ...
6
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2answers
593 views

Why is the Lucas test not recommended to differentiate higher alcohols?

I read about the Lucas test for alcohols in which a cloudy precipitate is produced with a tertiary or secondary alcohol. However, on a side note it was mentioned that this test is useful only for ...
6
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2answers
181 views

How to find trace methanol content in fermented fruit/distillate?

Suppose we have some fermented (optionally also distilled) fruit/fruit juice. The sample therefore contains water, sugars, ethanol etc. Which analysis method is the simplest to find out whether the ...
5
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1answer
663 views

Purification of Ethanol

In Vogel's organic book, they have mentioned that in the Lund and Bjerrum method of purification of ethanol, magnesium is added, which forms ethanolate. But they said to activate the magnesium first ...
4
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0answers
561 views

Can oxidation of ethanol by copper(II) oxide yield copper(I) oxide as one of the products?

We know that ethanol is oxidised by copper(II) oxide to an aldehyde. Copper is reduced from $\ce{Cu^2+}$ to $\ce{Cu}$. Can this reaction, with some specific condition, yield $\ce{Cu2O}$ instead? That ...
4
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2answers
3k views

Reaction of ethylene glycol with PI₃ (P + I₂)

We know that $\ce{2P + 3I2 -> 2PI3}$ Ethylene glycol reacts with $\ce{PCl3}$ to give ethylene dichloride, but why does it gives ethylene when it reacts with $\ce{P + I2}$? I don't really know ...
3
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1answer
10k views

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 ...
3
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3answers
6k views

How to test for methanol?

I wanted to make some ethanol from baker's yeast and I used sucrose. I've made it and put it in a glass jar. I left it on a warm place (near the radiator) until the yeast died and after they died I ...
3
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1answer
1k views

What happens when deodorants or perfumes expire

I know that deodorants and perfumes have alcohol as their main ingredient so I was thinking what happens when their expiry date passes? I tried to search on google but got mixed results. Some say ...
2
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2answers
5k views

O-H infrared band dependence of alcohol concentration in water

With regard to IR spectroscopy, how would the O-H band change as an alcohol solution was diluted with water? I am referring to any alcohol, but for the sake of example we can use ethanol. I think ...
2
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3answers
4k views

RO (alkoxide) as a leaving group

Why is RO (alkoxide) a better leaving group than OH, despite RO being more unstable due to the electron donating effect of the alkyl group on RO? I read that the suitability of leaving groups is ...
2
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1answer
6k views

Pinacol pinacolone rearrangement

I was reading the topic alcohol in that I saw a reaction Pinacol pinacolone rearrangement . But I am not able to find the sterochemistry of the reaction . Can anyone please tell me the ...
2
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1answer
3k views

Halogenation of alcohols in the presence of ZnCl2

I know that $\ce{OH-}$ is usually a bad leaving group, but why does the following reaction occur via SN1 in presence of anhydrous $\ce{ZnCl2}$?
2
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1answer
3k views

How to name molecules with a hydroxyl group in a side chain?

TL;DR: Are there clear nomenclature rules for naming the below molecule? Today in school we learned about the nomenclature of alcoholes. Unfortunately, it was not mentioned what to do with hydroxyl ...
1
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1answer
370 views

Can an ether be selectively hydrolysed in the presence of an ester?

What reaction, or protection/deprotection can be used to transform the ether group of a molecule that also has an ester compound into an alcohol while keeping the ester unchanged? For example: The ...
1
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1answer
9k views

Is glycerol/glycerin soluble in ethanol?

As titled, I wish to know if glycerol/glycerin is soluble in ethanol (not soluble, slightly soluble, very soluble)
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1answer
7k views

Smell of the methanol [closed]

When I first time smell the methanol, for me it was similar to the benzene (completely different from the ethanol). But almost everywhere information says, that it should me very similar to the ...