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.

Filter by
Sorted by
Tagged with
21
votes
2answers
98k 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 $\ce{ RCl }$ ...
17
votes
3answers
40k 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
votes
4answers
9k 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 ...
15
votes
2answers
43k 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{...
6
votes
2answers
395 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 ...
12
votes
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
votes
1answer
10k 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
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 $\ce{ZnCl2}$?
5
votes
2answers
5k 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 ...
42
votes
1answer
88k 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
votes
5answers
38k 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 ...
7
votes
4answers
12k 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 ...
15
votes
1answer
847 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
votes
3answers
10k 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 ...
13
votes
1answer
15k 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....
4
votes
4answers
3k 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 ...
3
votes
1answer
584 views

Is Pinacol rearrangement the source for the ring expansion?

I have no idea what's happening as in the product (the answer is (a)) there is a new ring being formed on the left benzene. But as I studied after $\ce{H2O}$ leaves, a carbocation is then formed on ...
13
votes
4answers
20k 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 ...
10
votes
3answers
342 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
votes
2answers
801 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 ...
6
votes
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
votes
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
175 views

Why and how does ring expansion occur in the dehydration of (cyclobut-3-ene-1,2-diyl)dimethanol?

Can someone explain how does this ring expansion occur with the mechanism? I do understand that the hydride shift occurred because of carbocation stability but why did the ring expand? Can you please ...
2
votes
1answer
541 views

Oxidation of alcohols by Ceric Ammonium Nitrate

I have realized that reaction with ceric ammonium nitrate essentially results in coordination of alcohol with $\ce{Ce(IV)}$ and my teacher referred that we should be able to proceed it to form ketone ...
1
vote
1answer
1k 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
votes
1answer
107 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 ...
14
votes
4answers
52k views

How do you create primary amines from alcohols?

By a primary amine I mean a compound where the hydroxyl group of the corresponding alcohol is replaced with an amine group.
5
votes
1answer
1k views

Protonation of a compound having alcohol and ethereal linkage

I approached the problem this way: The ethereal oxygen gets protonated(due to greater + I , the electron density on it is higher, hence it is more likely to behave as a lewis base). Consequently the ...
9
votes
1answer
6k 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 ...
7
votes
2answers
532 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.
5
votes
3answers
8k 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
votes
1answer
6k 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
votes
2answers
236 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 ...
12
votes
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
votes
1answer
271 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
votes
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
votes
2answers
24k 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
votes
2answers
811 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 ...
4
votes
1answer
8k 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
votes
1answer
820 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
4k views

Explain volume contraction in mixtures of alcohol and water

Could someone explain why volume contraction occurs when you mix an alcohol such as ethanol with water in relation hydrogen bonding and the dipole-dipole forces?
3
votes
6answers
5k views

Storage of Urine

Not all may be favorable to this project, but I will explain what I am trying to do. I work at home, and instead of walking a moderate distance to the bathroom and loosing my focus, I've been, at ...
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 ...
1
vote
0answers
907 views

What is the function of ZnCl2 in lucas test?

One mechanism I found on the internet (even on chemistry stackexchange) for the lucas test is: Here I don't see ZnCl2 participating in any of the steps. So what does it actually do? Another ...
-2
votes
2answers
6k 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 ...
7
votes
1answer
813 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 ...
7
votes
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 $\ce{SO2Cl2}$. ...
6
votes
2answers
2k 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
votes
2answers
204 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 ...