Reaktion #76584

Reaktionsgleichung

LDA

n-BuLi

3-Bromophenylacetonitrile

2-Chlorobenzylthiocyanate

diisopropylamine

→

2-(3-bromophenyl)malononitrile

Ausbeute 113.7%

Lösungsmittel

Methylene chloride

benzene

benzene

benzene

Reaktionsbedingungen

Aufarbeitung

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

Vorschrift

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).

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