Why do alcohols not react with NaOH?

Watch this thread
thegreenchildren
Badges: 9
Rep:
? You'll earn badges for being active around the site. Rep gems come when your posts are rated by other community members.
#1
Report Thread starter 9 years ago
#1
In the past paper mark scheme it says Phenol reacts with NaOH but Alcohols do not react with NaOH. Why is this? This is not mentioned in my book. I am doing OCR Salters A2.
0
reply
EierVonSatan
Badges: 21
? You'll earn badges for being active around the site. Rep gems come when your posts are rated by other community members.
#2
Report 9 years ago
#2
Do you know why phenol reacts with NaOH?
0
reply
hicong
Badges: 1
Rep:
? You'll earn badges for being active around the site. Rep gems come when your posts are rated by other community members.
#3
Report 9 years ago
#3
Phenol is a VERY weak acid as the phenol molecules have weak tendencies to lose the H+ ion from the hydroxyl group. Alcohols are not
0
reply
thegreenchildren
Badges: 9
Rep:
? You'll earn badges for being active around the site. Rep gems come when your posts are rated by other community members.
#4
Report Thread starter 9 years ago
#4
(Original post by hicong)
Phenol is a VERY weak acid as the phenol molecules have weak tendencies to lose the H+ ion from the hydroxyl group. Alcohols are not
So alcohols don't lose the H+ ion easily?
1
reply
kalika_amz
Badges: 8
Rep:
? You'll earn badges for being active around the site. Rep gems come when your posts are rated by other community members.
#5
Report 9 years ago
#5
(Original post by thegreenchildren)
In the past paper mark scheme it says Phenol reacts with NaOH but Alcohols do not react with NaOH. Why is this? This is not mentioned in my book. I am doing OCR Salters A2.
hey, i'm doing ocr salters b too..

for something to react with naoh (a base) it must be a fairly strong acid (proton donor) because it needs to donate sufficent h+

alchols dont do this- the r-o- ion they form is unstable because charge is concentrated on the o- atom so there is no electron delocation. this means that the r-o- ion is unstable so position of equillibrium lies to the left. rather than donating h+, alcohols are more likely to accept h+

whereas

phenols form an r-o- ion where the - charge is delocalised over the benzene ring that the o is attached to. the r-o- ion is therefore more stable and so the position of equillibrium lies to the right and so phenols donate h+, forming stronger acid

acid + base (naoh) --> salt + h20

hope this helps and good luck for the exam on mon!
2
reply
kalika_amz
Badges: 8
Rep:
? You'll earn badges for being active around the site. Rep gems come when your posts are rated by other community members.
#6
Report 9 years ago
#6
(Original post by thegreenchildren)
So alcohols don't lose the H+ ion easily?
yes
0
reply
thegreenchildren
Badges: 9
Rep:
? You'll earn badges for being active around the site. Rep gems come when your posts are rated by other community members.
#7
Report Thread starter 9 years ago
#7
(Original post by kalika_amz)
hey, i'm doing ocr salters b too..

for something to react with naoh (a base) it must be a fairly strong acid (proton donor) because it needs to donate sufficent h+

alchols dont do this- the r-o- ion they form is unstable because charge is concentrated on the o- atom so there is no electron delocation. this means that the r-o- ion is unstable so position of equillibrium lies to the left. rather than donating h+, alcohols are more likely to accept h+

whereas

phenols form an r-o- ion where the - charge is delocalised over the benzene ring that the o is attached to. the r-o- ion is therefore more stable and so the position of equillibrium lies to the right and so phenols donate h+, forming stronger acid

acid + base (naoh) --> salt + h20

hope this helps and good luck for the exam on mon!
Thanks for your help! I kind of understand now but what does electron de location mean? And just to make sure, when you say the equilibrium lies to the left you mean that theres more of the alcohol and when it lies to the right there is more of the ion?
0
reply
sfhdfhdvfsgr
Badges: 0
Rep:
? You'll earn badges for being active around the site. Rep gems come when your posts are rated by other community members.
#8
Report 9 years ago
#8
not strong enough base blad
0
reply
kalika_amz
Badges: 8
Rep:
? You'll earn badges for being active around the site. Rep gems come when your posts are rated by other community members.
#9
Report 9 years ago
#9
(Original post by thegreenchildren)
Thanks for your help! I kind of understand now but what does electron de location mean? And just to make sure, when you say the equilibrium lies to the left you mean that theres more of the alcohol and when it lies to the right there is more of the ion?
sorry for the late reply

electron delocalisation is where your electron charge (which is negative) is spread (delocalised)

so in the case of phenols, the electron chanrge is spread, delocalised, over the benzene ring..

yeah

so: r-oh + h20 --> r-o- + h30+
(pretend the arrow is the equilibrium arrow)
so lies to the left would be the left hand side so the r-oh
and lies to the right is the right hand side the r-o- ion

hope this is okay
0
reply
thegreenchildren
Badges: 9
Rep:
? You'll earn badges for being active around the site. Rep gems come when your posts are rated by other community members.
#10
Report Thread starter 9 years ago
#10
(Original post by kalika_amz)
sorry for the late reply

electron delocalisation is where your electron charge (which is negative) is spread (delocalised)

so in the case of phenols, the electron chanrge is spread, delocalised, over the benzene ring..

yeah

so: r-oh + h20 --> r-o- + h30+
(pretend the arrow is the equilibrium arrow)
so lies to the left would be the left hand side so the r-oh
and lies to the right is the right hand side the r-o- ion

hope this is okay
Thank you. Good luck!
0
reply
Rhmanapaa
Badges: 2
Rep:
? You'll earn badges for being active around the site. Rep gems come when your posts are rated by other community members.
#11
Report 4 years ago
#11
but phenol is not so much strong acid than carboxylic acid
0
reply
Ashsh
Badges: 1
Rep:
? You'll earn badges for being active around the site. Rep gems come when your posts are rated by other community members.
#12
Report 2 years ago
#12
My next question is.. if R --O- ion is unstable due to concentration of negative charge ion on oxygen atom then why it only takes H ion to get neutralize itself, it may take Na also ( From NaOH) to form R-----O-----Na and H2O
0
reply
X

Quick Reply

Attached files
Write a reply...
Reply
new posts
Back
to top
Latest

Does school Maths prepare people well enough for the future?

Yes, it gives everyone a good foundation for any future path (7)
31.82%
Somewhat, if your future involves maths/STEM (12)
54.55%
No, it doesn't teach enough practical life skills (3)
13.64%
Something else (tell us in the thread) (0)
0%

Watched Threads

View All