Shifuqiang@mail.ccut.edu.cn

Halogenation Reaction

(X)C-X

t1/2 5.7hr t1/2 33hr

5-

berberine

1.1.1 1.1.2 1.1.3 ()1.1.4 N-1.1.5 1.1.6

1.1.1 F2

I2

XCl 65% 35%Br 88% 12%Cl2/Br2

1.1.1.1

X=H 88% 12%X=OCH3 63% 37%

20-251.1.1.2

1.1.1.3

52%*69%*33%*21%*13%*8%*1.1.1.4

1.1.1.5

1.1.1.6 Br2: Cl2/I2:

88%1.1.2

69%

1.1.3 ()

70~73%

70%

1.1.4 N-

N-

82%

Hydrocortisone)

Dalton

1.1.5 HI > HBr > HCl

71%90%

HBr

94%1.1.6 H

78%(endo/exo=80/20)

1.2.1 1.2.2

1.2.1.1 C-H>C-H>C-H(C.)(exo)70~95%

N-

N-1,5--

1.2.1.2

(X=Cl, Br)1.2.1.3

NBSWohlZiegler

48~53%

1.2.2.1

(LewisAlCl3, FeCl3, ZnCl2)

Cl2>BrCl>Br2>ICl>I2

94~97%

B:-

93%

89%

97%

56%23%

--

1.3.1 -1.3.1.1

88~96%

70~75%

53%32%

55~58%

1.3.1.2

(CH3CO-) -HX

-71%~74%

1.3.1.3 1,2-

83~85%SO2Cl2-

105alpha,beta-

5,5--2,2--4,6 5,5- (TCC)

-1,3-

1.3.2 --H-H

5,5--2,2--4,6-1,3-

~70%1.3.3.1

1.3.3.2

84%

~100%

62%

90%*9%*-1.3.4

90%*9%*83~85%

1.3.5 - RCOX, RCN, (RCO)2O, eg:75%

1.4.1

HX, PX3, PX5, SOCl2 >>>>HXHI>HBr>HCl>HF

SN1SN2 R+SN1

-PHXSN1HXSN1SN2

1.4.1.1 HX

HCl

Lucas(HCl+ZnCl2)

1.4.1.2

SNi: SN2:

DMFHMPADMFSOCl2

HMPASOCl2DMF

HMPA

DMF

1.4.1.3

SN2----

DMFVilsmeier-Haack

1.4.1.4 Ph3P

80%

Ph3P /NBSPh3PX2

(PhO)3PICH3Ph3P /NBS

(PhO)3PICH3P

1.4.1.5 Me3SiCl:

/

/

/alpha-

2--3--

1.4.2 PCl5, POCl3, HX, SOCl260~70, 0.5hr

(R)-(+)- and (S)-(-)-2,2'-Bis(diphenyl phosphino)-1,1'-Binaphthyl(BINAP), Organic Syntheses, Coll. Vol. 8, P.57; Vol. 67, P.20.COPCO()

1.4.3 1,4-eg:HXHI, HBr, KI/H3PO4

BF3BBr3Lewis US 4595765

/

PX3, PX5, POX3,SOX2> > >1.5.1

PCl5

PBr3/PCl3

>(>>)()

SOCl2

89

(DMAP)Lewis(ZnCl2)

(COCl)2~97%

/

/

alpha-

alpha-

1.5.2Hunsdriecker() CO2C

Kochi92

beta-

Barton

beta-

Barton60%

1.6.1 eg:X=Cl, Br, X=I, F

Acetone is employed as solvent in the classical version of the reaction. Acetone is used in order to take advantage of the relatively higher solubility of sodium iodide compared to sodium bromide or chloride. The precipitation of the chloride or bromide salts removes the ions from solution and drives the reaction to completion. In the synthesis of ether compounds, the reaction can be used to prepare a suitable alkyl iodide for use in the Williamson Ether Synthesis.The reaction can also be performed in other solvents and the reaction can be driven to completion by the addition of a large excess of iodide. The reaction can also be employed using a catalytic amount of iodide. The alkyl iodide product can be generated in situ where it reacts further, regenerating the iodide.The relative rates of reactivity of various alkyl halides in the Finkelstein reaction resembles the rates of reactivity observed in other nucleophilic substitution reactions. The reaction rate increases as the number of carbons bonded to the carbon atom bearing the halogen decreases. The reaction rate is significantly higher when the carbon atom that undergoes attack is adjacent to a double bond or aromatic ring. Allyl bromide and benzyl bromide have a much higher rate of reaction than simple primary alkyl halides such as ethyl bromide. Electron donors on such double bonds or aromatic rings tend to increase the rate of reaction. Electron withdrawing groups tend to decrease the rate. This is consistent with a transition state that places a developing positive charge on the carbon atom undergoing attack.One variant of the reaction involves converting an alcohol to an excellent leaving group such as a tosylate, and then converting the tosylate to the iodide. This sequence formally has the effect of converting an alcohol to an alkyl halide.

90%

Lewis DMF

1.6.2

1.6.3Sandmeyer()CuClCuBrHX

Gattermann():SandmeyerSandmeyer

Schiemann http://www.organicchem.com/Article/namereaction/200809/897.html

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