Reaction #464358

Reaction equation

Magnesium

iodine crystals

bromide

magnesium

Phenylpropylmagnesium bromide

hydrochloric acid

Diethylchlorophosphite

Phenylpropyl bromide

→

3-phenylpropylphosphinic acid

Yield 53.2%

Solvents

diethyl ether

water

diethyl ether

diethyl ether

Conditions

Workup

1. 1
   OtherAfter several minutes the iodine was consumed
2. 2
   workup.ADDITIONadditional phenylpropyl bromide was added
3. 3
   Other(1.5 hours)
4. 4
   Otherwas sealed
5. 5
   Otherstored at 5° C
6. 6
   Temperaturewhile maintaining a temperature between 0-10° C
7. 7
   OtherA thick white slurry formed
8. 8
   workup.STIRRINGwas stirred an additional 30 minutes
9. 9
   FiltrationThe mixture was filtered under a nitrogen atmosphere
10. 10
    Otherthe filtrate evaporated under reduced pressure
11. 11
    Otherto give a clear and colorless liquid
12. 12
    OtherAn exothermic reaction
13. 13
    workup.STIRRINGstirring
14. 14
    Extractionfollowed by extraction with ethyl acetate
15. 15
    Washwashed with brine
16. 16
    Dryingdried (MgSO4)
17. 17
    Otherevaporated
18. 18
    workup.ADDITIONTo the clear liquid was added sodium hydroxide (40 mL, 2.0 M NaOH)
19. 19
    workup.STIRRINGthe resulting solution stirred for 1 hour
20. 20
    Washwashed with diethyl ether
21. 21
    Extractionextracted twice with ethyl acetate
22. 22
    Dryingdried (MgSO4)
23. 23
    Otherevaporated

Procedure

Magnesium turnings (2.44 g, 0.10 mol) in 20 mL of dry diethyl ether under an atmosphere of nitrogen was added several iodine crystals. Phenylpropyl bromide (20.0 g, 0.10 mol) in 80 mL of diethyl ether was placed in a dropping funnel. Approximately 10 mL of the bromide solution was added to the magnesium turnings and stirring was initiated. After several minutes the iodine was consumed and additional phenylpropyl bromide was added while maintaining a temperature of 35° C. Once additional was complete (1.5 hours) the mixture was sealed and stored at 5° C. Diethylchlorophosphite (15.7 g, 0.1 mol) in 50 mL of dry diethyl ether was cooled to 5° C. under an atmosphere of nitrogen. Phenylpropylmagnesium bromide (100 mL, 0.1 mol, 1.0 M solution of in Et2O) was added dropwise over 2 hours while maintaining a temperature between 0-10° C. A thick white slurry formed and was stirred an additional 30 minutes. The mixture was filtered under a nitrogen atmosphere and the filtrate evaporated under reduced pressure to give a clear and colorless liquid. To the liquid was added 20 mL of water followed by 0.5ml of concentrated hydrochloric acid. An exothermic reaction was observed and stirring continued for 20 minutes followed by extraction with ethyl acetate. The organics were combined, washed with brine, dried (MgSO4) and evaporated. To the clear liquid was added sodium hydroxide (40 mL, 2.0 M NaOH), the resulting solution stirred for 1 hour and then washed with diethyl ether. The aqueous layer was acidified to pH 1.0 with concentrated hydrochloric acid and extracted twice with ethyl acetate. The organics were combined, dried (MgSO4) and evaporated to give 3-phenylpropylphosphinic acid (1,R=CH2CH2CH2Ph,R1=H)(9.8 g, 53%) as a clear and colorless oil.

Source