Organometallic Reagents Carbon is bonded to a metal (Mg or Li). Carbon is nucleophilic(partially negative). It will attack a partially positive carbon. C-X C=0 A new carbon-carbon bond forms
Organometallic Reagents ❖Carbon is bonded to a metal (Mg or Li). ❖Carbon is nucleophilic (partially negative). ❖It will attack a partially positive carbon. ◼C - X ◼C = O ❖A new carbon-carbon bond forms
Grignard Reagents Formula R-Mg-X (reacts like R:+MgX) Stabilized by anhydrous ether Iodides most reactive May be formed from any halide -Primary,secondary,tertiary,vinyl,aryl Limitations of Grignard -No water or other acidic protons like O-H,N-H,S-H,or-C-C-H.Grignard reagent is destroyed,becomes an alkane. -No other electrophilic multiple bonds,like C=N,C=N, S=0,orN=0
Grignard Reagents ❖Formula R-Mg-X (reacts like R:- +MgX) ❖Stabilized by anhydrous ether ❖Iodides most reactive ❖May be formed from any halide ◼Primary, secondary, tertiary, vinyl, aryl ❖Limitations of Grignard ◼No water or other acidic protons like O-H, N-H, S-H, or -C—C-H. Grignard reagent is destroyed, becomes an alkane. ◼No other electrophilic multiple bonds, like C=N, CN, S=O, or N=O
Some Grignard Reagents B ether MgBr Mg CI MgCI CH3CHCH2CH3 ether Mg CH3CHCH2CH3 CH3C=CH2 Br Mg ether CH3C=CH2 MgBr
Some Grignard Reagents Br + Mg ether MgBr CH3CHCH2CH3 Cl ether + Mg CH3CHCH2CH3 MgCl CH3C CH2 Br + Mg ether CH3C CH2 MgBr
Organolithium Reagents Formula R-Li (reacts like R:+Li) Can be produced from alkyl,vinyl,or aryl halides,just like Grignard reagents. Ether not necessary,wide variety of solvents can be used
Organolithium Reagents ❖Formula R-Li (reacts like R:- +Li) ❖Can be produced from alkyl, vinyl, or aryl halides, just like Grignard reagents. ❖Ether not necessary, wide variety of solvents can be used
Reaction with Carbonyl R:attacks the partially positive carbon in the carbonyl. The intermediate is an alkoxide ion. Addition of water or dilute acid protonates the alkoxide to produce an alcohol. OH
Reaction with Carbonyl ❖R:- attacks the partially positive carbon in the carbonyl. ❖The intermediate is an alkoxide ion. ❖Addition of water or dilute acid protonates the alkoxide to produce an alcohol. R C O R C O HOH R C OH OH