70545143 organic II reactions BETA

tóm tắt phản ứng hóa hữu cơ part 1 hóa học hữu cơ là một ngành khoa học nghiên cứu về những cấu trúc, tính chất, thành phần, cách thức phản ứng, và cách tổng hợp của những hợp chất hữu cơ và vật liệu hữu cơ... cũng như nhiều vật chất khác nhau chứa nguyên tử carbon.12 Quá trình nghiên cứu cấu trúc hóa học của một hợp chất hữu cơ có thể ứng dụng nhiều thành tựu trong các lĩnh vực khác phải kể đến như phương pháp quang phổ, phương pháp vật lý và hóa học để định danh và xác định thành phần hóa học cũng như cấu tạo của hợp chất.3 Hóa hữu cơ nghiên cứu các đặc tính lý hóa của hợp chất, đánh giá mức độ phản ứng cũng như xác định tính chất của chúng ở trạng thái tinh khiết, trong dung dịch, hỗn hợp và các dạng khác. Các nghiên cứu về phản ứng hữu cơ có thể kể đến bao gồm việc chuẩn bị cho các phản ứng tổng hợp hữu cơ, nghiên cứu mức độ hoạt động của phản ứng, cũng như nghiên cứu các mô hình lý thuyết trên máy tính

Symmetrical

ethers through

dehydration of 1o

alcohols

*cannot be unsymetrical (you will get mixtures!)

x 2

H2SO4

140oC

Cleavage of ethers

byvstrong acids

+ H 3 C Br

O

HBr

O H Br

*can also use HI, HCl, etc

* vinyl or aryl do not get cleaved (NO SN2 ON SP2)

Autoxidation

R

R

O2 (xs) slow

R

R

R R R

*basically forms peroxides which EXPLODE!

O

MCPBA *epoxide will form along

the more substituted alkene

Intramolecular

C

OH

Cl

3

*SN2 like

*forms O- that attacks halogenated C

H3O+

H2O

CH 3

D O

CH 3

D OH OH

CH 3

D O

1)-OH 2)H3O+

OH

OH D

CH 3

Opening of

Epoxides

*activate the O first

*weak Nu are good

*more substituted side

attacked

*SN2 like (least subs)

so strong Nu and base

*Grignard reagent and acetylide anion can work tooo

Task Reaction Notes

Free Radical

Halogenation

Expanded

NBS

hv 0oC

*Low T: more stable TS

*High T: more stable

compound

Br

Br

CH3

CH3

CH3

CH3

transition state

NBS

60oC

Conjugated

Systems

C

HBr

*in this example we will examine the case of HBr

Br2

H3O+

HBr / 0oC HBr / 40oC

C

H

H

transition state

*Low T: more stable TS

*High T: more stable

compound

*NOTE: If more than one conjugated system possibly exists, examine the transition states of each one and do the reactions with the more stable transtion states!

Diels-Alder

Reaction

D = donating group W = withdraw group

D

+

W

heat D

W

D

W

D W

*1,2 or 1,4 adduct

*know endo rule

*Diene and Dienophile

*Know Stereochem

*PRACTICE THIS!!!

Task Reaction Notes

Halogenation of

(I2 / CuCl2)

X *X = Cl or Br

HNO3

H2SO4 heat

Nitration of

Benzene

*H2SO4 acts as a catalyst

SO3 / H2SO4 heat

SO 3 H *REVERSIBLE DUE TO

ENTROPY

Sulfonation

(fuming sulfuric)

+ H 2 SO 4

Friedel-Crafts

Alkylation

RCl AlCl3

R

*watch rearrangement!

*no strong deactivators (no strong W grps)

*no amino groups

*watch for polyalkylation

Friedel-Crafts

Acetylation

AlCl3

R

O O

R Cl

*no strong deactivators (no strong W grps)

*no amino groups

CO / HCl AlCl3 / CuCl

H

O

Gatterman-Koch

Formation

(forming

benzaldehyde)

*no strong deactivators (no strong W grps)

*no amino groups

Clemmensen

Reduction

R

O

Zn(Hg)

*avoid using this reactant in the presence

of alkenes, alkynes, alcohols and amines

Task Reaction Notes

Nucleophilic

Aromatic

Substitution of Aryl

Halides:

Addition /

Elimination

W W

W

X

Nu (2eq) heat, pressure W W

W

Nu

*need Strong W groups

ortho and/or para to

leaving group.

*Nu can be OH-, RO-,

NH3

*NOTE: If - OCH3 is the

Nu, only need 1 eq

W = withdraw group X = leaving grp (halide) Nu = nucleophile

Nucleophilic

Aromatic

Substitution of Aryl

Halides:

Elimination /

Addition

X

NaNH2 /

NH3 (l)

+

X

1) NaOH (2eq) / 340 o C / 2500 psi 2) H3O +

group is not O/P

*formation of benzyne

in mechanism

* Nu can be OH-, RO-,

-NH2.

*will get a mixture (like second example)

Chlorination of

Benzene

3 Cl2 / heat pressure

Cl Cl

Cl Cl Cl

Cl

*8 different stereochems actually occur

*this particular molecule

is the commercial

compound Rid

(lice killer)

Catalytic

Hydrogenation

3 H2 / 1000 psi / 100oC

Ru or Rh (Pt,Pd,Ni also)

0 or Li0

NH3(l) / ROH

W

D

*withdraw groups -> sp3

*donating groups -> sp2

Reduction of Nitro

group into Amino

Group

Zn, Sn, or Fe

*Do not confuse with Clemmenson Red

Side Chain Rxn:

Oxidation

*Can use either reagent

*Does not work for bulky groups

(CH2)n

O

KMnO4/H2O

OH-/100oC

Na2Cr2O7 / H2SO4 heat

CO2H

CO2H

CO2H

HO2C

Halogenation of

Cl

Cl +

54% 44%

Br2 (or NBS) / light

Br

*If aromatic ring is activated, use NBS instead of Br2

*Pay attention to Temp (if it's low or high)

*WILL EXPLAIN THIS BETTER IN CLASS

Nucleophilic Subs

of Benzylic

Halides

CH2Br CH

3OH heat

+

+

major! *SN1 or SN2 or E2?

Depends on conditions!

*Resonance form that does not disrupt the aromaticity is more stable

CH2OCH3

*SN1

Br

CH3CH2O

Na+

NaI acetone

*SN2

*E2

I

Rxns of phenols

similar to alochols

OH

NaOH

RCO2H

or RCOCl

PBr3

O

O

(no rxn)

OH

(no rxn)

*2nd rxn is Fischer Estherification

*3rd rxn is only one that

is different!

Task Reaction Notes

Oxidation of

Phenols to

Quinones

*This reaction forms a D-A dienophile!

O

H OH Na2Cr2O7

H2SO4

Formation of

2) CO2 3) H3O+

OH

OH O

*Phenoxide anion can react with the weak electrophile because it

is so strongly activated

REVIEW:

Oxidation of

alcohols

2o alcohols

OH

Na2CrO7

H2SO4 / H2O

CrO3 / H2SO4 / H2O acetone / 0oC (Jones reagent)

PCC

CH2Cl2

O

*any [ox] can be used

*KMnO 4 and NO 3 can

be used but they are harsh

1o alcohols

CH2Cl2

O

H

*Only use PCC because Jones reagent will yield carboxyllic acid

REVIEW:

Cleavage of

Alkenes by

Ozonolysis

C

1) O3 2) (CH3)2S

O

C

H

O

+

REVIEW:

Hydration of

Alkynes

H2O / H2SO4 HgSO4

1) Sia2BH 2) H2O2 / OH

either reagent

H

H R

O H

OH

H R

H

R O

O H

mixture of ketones

*Really know the mechanism now and how the enols tautomerize

Dithiane Synthesis

of Aldehydes and

Ketones

*Dithiane will be given

*BuLi =

CH3(CH2)2CH2-Li

*Halide must be methyl

or 1o

S S

1) BuLi 2) R - X S S

1) BuLi 2) R1 - X

H3O+

O

S S

H3O+

O

Ketones from

Carboxylic Acids

O 1) R1 - Li (2eq)

2) H3O+

is used to make salt

Ketones from

Nitriles

R

1) R1-MgX 2) H3O+ R R 1

O

Aldehydes from

Acid Chlorides

O LiAlH(OtBu)3

*lithium aluminum tri(t-butoxy)hydride

O

H2 / Pd / BaSO4 / S

*Rosenmund Reduction

Ketones from

Acid Chlorides

O

(R1)2CuLi

O

*Make sure you know how to form Gilman Reagent (refer to House in previous rxn sheet)

Wittig Reaction:

Ald and Ketones

ONLY

H

H H

+

maj

*Know how to prep the phosphorous ylide!

*trans is more stable because you want bulky groups to be furthest away from each other

Task Reaction Notes

Aldehydes and

Ketones:

Formation of

Cyanohydrins

*Aldehydes or unhindered ketones

*will use this as a reagent in the future

O

-CN HCN

C

OH

H

O

NaCN

H+

C

OH

H

Aldehydes and

Ketones: Addition

O RNH

2

H+

*non AQ favors reactant

*AQ favors product

Wolf-Kishner

Reaction

*avoid halogens and other good LGs

(Use Clemmensen instead)

O

NH2NH2 KOH/DMSO

Aldehydes and

Ketones: Addition

of 2o Amines

H3O+

Acetal Formations

"protected

carbonyls"

O

2(CH3CH2OH)

H+

EtO OEt

*easier to just use

OH OH

O

O H

1) /H+ 2) CH3MgBr 3) H3O+

OH OH

*aldehyde protected before ketone because

it is more reactive

O

H

O O

H

O O

O- CH3

H

CH3 O

H

O