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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18
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2answers
86k 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 $\ce{ RCl }$ ...
14
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3answers
35k 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
8k 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 ...
13
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2answers
40k 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{...
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
votes
1answer
3k 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
9k 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 ...
4
votes
2answers
4k 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 ...
40
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1answer
86k 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
11k 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
33k 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
800 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 ...
11
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3answers
8k 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 ...
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
17k 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 ...
5
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1answer
2k 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
votes
2answers
305 views

False positive in lucas test for primary alcohol due to formation of tertiary carbocation by rearrangement?

From Wikipedia: The Lucas test in alcohols is a test to differentiate between primary, secondary, and tertiary alcohols. It is based on the differences in reactivity of the three classes of alcohols ...
1
vote
1answer
860 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
103 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 ...
7
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2answers
351 views

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.
9
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1answer
5k 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 ...
4
votes
2answers
261 views

Formation of toluene from (cyclobutane-1,2,3-triyl)trimethanol using conc. sulphuric acid

In my book this reaction is given without any mechanism: I thought that simple dehydration reaction is going to take place with rearrangement of the carbocation but I have no idea as to how toluene ...
3
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3answers
6k 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
4k 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 $\...
12
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1answer
13k 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....
11
votes
1answer
261 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 ...
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}...
9
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2answers
19k 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 $\ce{PCl3}$ ?
8
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2answers
715 views

Producing ketones from secondary alcohols using hydrogen peroxide

Usually, to produce ketones from secondary alcohols (e.g. propanone from 2-propanol), people use a solution of potassium or sodium dichromate with a small amount of sulfuric acid. Can other oxidizers ...
5
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3answers
3k views

Why can't primary alcohols react with sodium bromide via an SN2 mechanism?

I was told that a primary alcohol reacts with $\ce{HBr}$ for example, but not with $\ce{NaBr}$ through the $\mathrm{S_N2}$ mechanism in the same reaction environment. Why? This reaction can occur: $$...
4
votes
1answer
6k 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?
4
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1answer
728 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 ...
3
votes
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
votes
1answer
2k 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 ...
2
votes
2answers
143 views

Rate of dehydration of alcohols having keto group

The following question was asked in IITJEE-Screening 2000, Which of the following will be most readily dehydrated in acidic conditions? I thought that the answer would simply be (c), as its ...
-2
votes
2answers
5k 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
3k 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 ...
11
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3answers
13k views

Is there a way to turn alcohol into a solid gel?

I'm wondering if there is a way to turn alcohol or another bacteria killing substance into a solid gel form, sort of like the gel you can use to clean a keyboard. Source: Aliexpress.com Computer ...
10
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3answers
300 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. ...
7
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2answers
3k 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
votes
1answer
654 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 of ...
6
votes
2answers
196 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 ...
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 ...
5
votes
2answers
628 views

Rate of O exchange with H2O

We have to find the order of rate of exchange of O with H2O of the following compounds $\ce{CCl3CHO}$ $\ce{CH3CHO}$ $\ce{CH3COCH3}$ $\ce{CF3CHO}$ According to me, higher rates of exchange would be ...
5
votes
1answer
727 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 ...
5
votes
2answers
978 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 ...
4
votes
0answers
600 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 ...
3
votes
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 ...
3
votes
1answer
11k 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 ...