rate eqaution exam questionWatch

Thread starter 9 months ago
#1
Rate= K [CH3CHO] [OH-]

equation 2CH3CHO----> CH3CH(OH)CH2CHO

it asks to draw how X which is the product above reacts with ethanal, is this nucleophilic addition, idk how to draw the mechanism to determine what the product is, if I draw ethanal, what is the nucleophile in this case?
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Thread starter 9 months ago
#2
(Original post by usernamenew)
Rate= K [CH3CHO] [OH-]

equation 2CH3CHO----> CH3CH(OH)CH2CHO

it asks to draw how X which is the product above reacts with ethanal, is this nucleophilic addition, idk how to draw the mechanism to determine what the product is, if I draw ethanal, what is the nucleophile in this case?
heres the quesiton
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9 months ago
#3
(Original post by usernamenew)
heres the quesrtion
attachment not relevant? i think you posted wrong attachment

(Original post by usernamenew)
Rate= K [CH3CHO] [OH-]

equation 2CH3CHO----> CH3CH(OH)CH2CHO

it asks to draw how X which is the product above reacts with ethanal, is this nucleophilic addition, idk how to draw the mechanism to determine what the product is, if I draw ethanal, what is the nucleophile in this case?
it's nucleophilic addition (catalysed by OH- which appears in the rate law)

you know 2CH3CHO----> CH3CH(OH)CH2CHO

so CH3CH(OH)CH2CHO + CH3CHO - > ...
proceed in similar way to the first one
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Thread starter 9 months ago
#4
(Original post by BobbJo)
attachment not relevant? i think you posted wrong attachment

it's nucleophilic addition (catalysed by OH- which appears in the rate law)

you know 2CH3CHO----> CH3CH(OH)CH2CHO

so CH3CH(OH)CH2CHO + CH3CHO - > ...
proceed in similar way to the first one
so the mechanism with OH- gives ethanol, do i just add that to the product CH3CH(OH)CH2CHO?
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9 months ago
#5
(Original post by usernamenew)
so the mechanism with OH- gives ethanol, do i just add that to the product CH3CH(OH)CH2CHO?
it doesn't give ethanol? are we talking about the same question?
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Thread starter 9 months ago
#6
(Original post by BobbJo)
it doesn't give ethanol? are we talking about the same question?
i mean ethanal with OH- gives ethanol , then do u add that to the product to give the trimer
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9 months ago
#7
(Original post by usernamenew)
so the mechanism with OH- gives ethanol, do i just add that to the product CH3CH(OH)CH2CHO?
first reaction gives 2-hydroxybutanal

so

react CH3CH(OH)CH2CHO with CH3CHO in a similar way to the first
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Thread starter 9 months ago
#8
(Original post by BobbJo)
first reaction gives 2-hydroxybutanal

so

react CH3CH(OH)CH2CHO with CH3CHO in a similar way to the first
thank u, with the first reaction u did CH3CH(OH)CH2CHO +OH-?
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9 months ago
#9
no it's not + OH-

OH- is only a catalyst

first reaction is this

2CH3CHO----> CH3CH(OH)CH2CHO

second reaction is

CH3CH(OH)CH2CHO + CH3CHO -> write formula of product
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Thread starter 9 months ago
#10
(Original post by BobbJo)
no it's not + OH-

OH- is only a catalyst

first reaction is this

2CH3CHO----> CH3CH(OH)CH2CHO

second reaction is

CH3CH(OH)CH2CHO + CH3CHO -> write formula of product
i thought OH- was needed for nucleophilic addition to make CH3CH(OH)CH2CHO, 2 ethanals cant make that product ? sorry im confused, if i was to draw a mechanism for the first reaction i would use OH- as a nucleophile?
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9 months ago
#11
(Original post by usernamenew)
i thought OH- was needed for nucleophilic addition to make CH3CH(OH)CH2CHO, 2 ethanals cant make that product ? sorry im confused, if i was to draw a mechanism for the first reaction i would use OH- as a nucleophile?
i see the required attachment now, not sure what went wrong the first time ( I was seeing .... / 9 = 80 something)

do you need to draw the mechanism ? what is the full question?

just for the structure, you don't need the mechanism, you can just deduce it by comparing with first reaction

OH- accepts hydrogen on CH3 next to aldehyde group
new negative charge moves to form a pi bond, pi electrons on C=O move onto the O
pi bond breaks heterolytically
electrons move from pi bond to form a new C-C bond with a CH3CHO molecule
pi electrons on C=O on the other molecule move onto the O
O- accepts a proton
product is formed
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9 months ago
#12
(Original post by usernamenew)
Rate= K [CH3CHO] [OH-]

equation 2CH3CHO----> CH3CH(OH)CH2CHO

it asks to draw how X which is the product above reacts with ethanal, is this nucleophilic addition, idk how to draw the mechanism to determine what the product is, if I draw ethanal, what is the nucleophile in this case?
CH3CH(OH)CH2CH(OH)CH2CHO
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