Réaction #76584

Équation de réaction

LDA

n-BuLi

3-Bromophenylacetonitrile

2-Chlorobenzylthiocyanate

diisopropylamine

→

2-(3-bromophenyl)malononitrile

Rendement 113.7%

Solvants

Methylene chloride

benzene

benzene

benzene

Conditions de réaction

Traitement

1. 1
   SéchageTo a flame dried 5L 3-neck flask
2. 2
   Autreequipped with a mechamical overhead stirrer under nitrogen
3. 3
   Autreat 0-5° C
4. 4
   workup.ADDITIONwas added dropwise via addition funnel
5. 5
   Autreat 0-5° C
6. 6
   workup.ADDITIONwas added dropwise via addition funnel
7. 7
   Autreat 0-5° C
8. 8
   workup.ADDITIONDuring the addition
9. 9
   Autrea precipitate formed
10. 10
    Températureto warm to room temperature
11. 11
    workup.STIRRINGthe mixture stirred overnight
12. 12
    AutreThe reaction was quenched
13. 13
    workup.ADDITIONby adding water and 200 mL 10% NaOH
14. 14
    AutreThe layers were separated
15. 15
    Extractionthe benzene layer extracted with 10% NaOH (3×1 L)
16. 16
    AutreThe basic layers were collected
17. 17
    AutreA precipitate formed
18. 18
    workup.DISSOLUTIONto dissolve the precipitate
19. 19
    AutreThe layers were separated
20. 20
    AutreThe methylene chloride layers were collected
21. 21
    Séchagedried (MgSO4)
22. 22
    Autrethe solvent removed in vacuo

Mode opératoire

To a flame dried 5L 3-neck flask equipped with a mechamical overhead stirrer under nitrogen was added diisopropylamine (78.60 mL, 0.56 mol, 2.2 eq) and 2 L of benzene. After cooling to 0-5° C., 1.6 M n-BuLi (351.0 mL, 0.56 mol, 2.2 eq) was added dropwise via addition funnel while keeping the temperature at 0-5° C. The LDA was stirred for 45 min. at 0-5° C. 3-Bromophenylacetonitrile (50.0 g, 0.26 mol, 1.0 eq) dissolved in 200 mL of benzene was added dropwise via addition funnel keeping the temperature at 0-5° C. The mixture was stirred an additional 15 min at this temperature. 2-Chlorobenzylthiocyanate (J. Am. Chem. Soc., 1954, 76, 585) (103.0 g, 0.56 mol, 2.2 eq) dissolved in 200 mL benzene was added dropwise via addition funnel keeping the temperature at 0-5° C. During the addition, a precipitate formed. The reaction was allowed to warm to room temperature and the mixture stirred overnight. The reaction was quenched by adding water and 200 mL 10% NaOH. The layers were separated, and the benzene layer extracted with 10% NaOH (3×1 L). The basic layers were collected and acidified with conc. HCl to pH 1-2. A precipitate formed. Methylene chloride was added to dissolve the precipitate. The layers were separated and the aqueous layer reextracted with methylene chloride (2×). The methylene chloride layers were collected, dried (MgSO4) and the solvent removed in vacuo to yield 65.32 g of 2-(3-bromophenyl)malononitrile as a yellow solid. Recrystallization from methylcyclohexane yielded two crops: crop 1, 42.86 g of orange crystals, m.p. 99.5-101.5° C.; crop 2, 2.18 g of orange crystals, m.p. 97.0-99.0° C. Combined yield 79.9%. 1H-NMR (CDCl3) δ: 7.67 (s, 1H); 7.63 (d, 1H, J=7 Hz); 7.47 (d, 1H, J=7 Hz); 7.39 (t, 1H, J=7 Hz); 5.08 (s, 1H).

Source