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Compounds that contain _________________bond (______): Examples of M include ________(Grignard reagents), _____________. ____________ carbon: Reacts with.

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Presentation on theme: "Compounds that contain _________________bond (______): Examples of M include ________(Grignard reagents), _____________. ____________ carbon: Reacts with."— Presentation transcript:

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2 Compounds that contain _________________bond (______): Examples of M include ________(Grignard reagents), _____________. ____________ carbon: Reacts with _____________ carbon and forms a new _________________. Nomenclature: Similar naming to substituted metals (alkyl metals or alkyl metal halides). Organomagnesium: Grignard reagent. CH 3 Li: Methyl lithium. CH 3 MgBr: Methyl MgBr. Organometallic Compounds

3 Properties: High Reactivity: Organmometallics are usually kept in organic solvents due to their very high reactivity. Reacts especially with H 2 O, O 2, etc. RMgX + H 2 O  RMgX + O 2  Organometallic Compounds

4 Structure: Ionic Character: R-M = R- M+ NaR and KR are __________. Electronegativities: Na: 0.9, K: 0.8, C: 2.5 LiR and MgR have a sigma bond between the carbon atom and the metal. These are ________compounds. Electronegativities: Li: 1.0, Mg: 1.2 Organometallic Compounds CH 3 Li CH 3 F

5 Reactivity: Bases act as ___________ Basicity: Simple carbanions are _____________. Carbon is not very electronegative compared to nitrogen or oxygen. RLi + HOR  _________ RMgX + HOR  ______________ RLi or RMgX _________ be used in the presence of _____________, such as –___________ Organometallic Compounds

6 1. 1.Nucleophilic Substitution: R 2 CuLi reaction with alkyl halides or tosylates Nucleophilic Addition: RLi or RMgX with aldehydes or ketones Nucleophilic Acyl Substitution: RLi or RMgX with esters. General Mechanisms Nu C LG LG N u C O C Nu Nu C LG O C ONu LG C O Nu LG

7 Reaction Type: Alkyl halides react with lithium metal. Other Group I metals (Na, K) can be used instead of lithium. Solvents: Alkyl group can be. R can be. Halide Reactivity: Organolithium Reagents RX + 2 Li  RLi + Li+X- (X = I, Br, Cl)

8 Limitations: Organolithium, RLi, is _____________for an S N 1 or S N 2 with alkyl halides or tosylates. This gives __________________ reaction or other side reactions. Organolithium Reagents RX + 2 Li  RLi + Li+X- (X = I, Br, Cl)

9 Reaction Type: Alkyl halides react with magnesium metal. Solvents: Alkyl group can be primary, secondary or tertiary. R can be alkyl, vinyl or aryl. Halide Reactivity: Organomagnesium Reagents Et 2 O RX + Mg  RMgX (X = I, Br, Cl)

10 Limitations: Organomagnesium, RMgX is ___________for S N 1 or S N 2 with alkyl halides or tosylates. In these situations, RMgX gives ___________ reactions and other side reactions. Common Reactions with Carbonyl Groups: Aldehydes/Ketones: RLi and RMgX react with the _____________ Organomagnesium Reagents Et 2 O RX + Mg  RMgX (X = I, Br, Cl)

11 Common Reactions with Carbonyl Groups: Aldehydes/Ketones: RLi and RMgX react with the carbonyl (C=O) to create _____________. Addition to methanal (formaldehyde)  __________. Addition to other aldehydes  ______________. Addition to ketones  ____________. The acidic work-up intermediate metal alkoxide salt  alcohol via a simple _________ reaction. Organomagnesium Reagents Et 2 O RX + Mg  RMgX (X = I, Br, Cl)

12 Organomagnesium Mechanism RMgX C HH O RMgX C R'H O RLi RMgX C R"R' O RLi C O R' R H H C O H R H H C O R' R R" H or or or C OH H R H C OH R' R H RLi C OH R' R R

13 Reaction Type: Requires ________ equivalents of organolithium or Grignard reagents. Product: _______________ Tertiary alcohol contains ______________ alkyl groups via a _____________which reacts with the second equivalent of the organometallic. Since the ketone is ________________ than the ester, the reaction _______ stop at a ketone. Esters

14 Grignard Reactions R’ = Alkyl, vinyl, aryl. X = Cl, Br, I R’MgX H 2 CO RCHO RCOR RCN CO 2 RCO 2 Et (EtO) 2 CO HCO 2 Et Mg/Ether R’X O H 2 O or acidic H

15 Lithium Dialkylcuprates, R 2 CuLi _____ organolithiums with a copper (I) halide. Solvents: The alkyl group is usually ____________. _____________are prone to decomposition. R can be _________________________. Halide Reactivity: Organocopper Reagents Et 2 O 2 RLi + CuX  R 2 CuLi + Li + X - (X = I, Br, Cl)

16 Limitations: Organocuprates, R 2 CuLi, are __________ and can be reacted with _____________________ to give alkanes. Organocopper Reagents Et 2 O 2 RLi + CuX  R 2 CuLi + Li + X - (X = I, Br, Cl)

17 Alkane Synthesis Using R 2 CuLi: R 2 CuLi + R’-X  R-R’ + RCu + LiX Reaction Type: Creation of new C-C bonds. ______________are best, otherwise an elimination reaction can occur. The R’ group in the halide can be ______________ The R group of the cuprate can be ______________ Although the mechanism looks like a _________ reaction, it is more complex and is not well understood. Organocopper Reagents

18 Reaction Type: RZnX is made in a similar fashion as RZnX is _________ reactive than RLi or RMgX with aldehydes and ketones. The most common application of organozinc reagents is in the Simmons-Smith Reaction. Organozinc Reagents Et 2 O RX + Zn  RZnX (X = I, Br, Cl)

19 Synthesis of Cyclopropanes using RZnX Known as the Simmons-Smith Reaction Iodomethyl zinc iodide is usually prepared using Zn and activated with Cu. Iodomethyl zinc iodide reacts with an alkene to give a Organozinc Reagents Et 2 O ICH 2 I + Zn  I-CH 2 -ZnI Cu Et 2 O I-CH 2 -ZnI + =—R  + ZnI 2

20 Synthesis of Cyclopropanes using RZnX Reaction is __________specific with respect to the alkene. Mechanism is ____________. Substituents that are _______ in the alkene are ______ in the cyclopropane. Substituents that are______ in the alkene are ______ in the cyclopropane. Organozinc Reagents I-CH 2 ZnI CH 3 CH 3 Et 2 O ZnI 2 I-CH 2 ZnI CH 3 CH 3 Et 2 O ZnI 2

21 Mechanism of the Simmons-Smith Reaction Reaction is ________________. Both new C-C bonds are formed simultaneously. Nucleophilic C=C causes loss of iodide leaving group. Electrons from nucleophilic C-Zn bond form the other C-C bond. Organozinc Reagents CH 2 I ZnI CH 2 ZnI 2 +

22 Reaction Type: Reacts as a _______________ 3 important groups of reactions where nucleophiles attack electrophilic C atoms. Product is new C-C bonds. Acetylenic Reagents B:- (B:- = NaNH 2 ) R—CΞC—H  R—CΞC:- + B-H Or B:- (B:- = R’MgX) R—CΞC—H  R—CΞC:- MgX + R’-H

23 Acetylenic Mechanism CLi RC CMgXRC C HH O C O R' H H C O H H H C O R' R" H or C OH H H C OH R' H C OH R' R" C R'H O CMgX RC CLi RC or C R"R' O CMgXRC CLi RC or C=O in aldehydes/ketones  alcohols. Addition to methanal (formaldehyde) gives __________________. Addition to other aldehydes gives ______________________. Addition to ketones gives tertiary _____________.


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