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Chapter 10 Organometallic compounds. 10.1 Introduction 10.2 Preparation of organolithium and organomagnesium compounds 10.3 Carbanions as Br ø sted bases 10.4 Applications of organometallic comp. in organic synthesis

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Chapter 10 Organometallic compounds

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Chapter 10 organometallic compounds

Chapter 10

Organometallic compounds

10.1 Introduction

10.2 Preparation of organolithium and

organomagnesium compounds

10.3 Carbanions as Brøsted bases

10.4 Applications of organometallic

comp. in organic synthesis

10.4.1 Synthesis of alcohols using

Grignard reagents

10.4.2 Retrosynthetic analysis

10.4.3 Alkane synthesis by using

organocopper reagents

10.4.4 Ziegle-Natta Catalysis of alkene

polymerization


Chapter 10 organometallic compounds

Depend on

Covalent bond

Ionic bond

M= Na+or K+

M=Mg, Li

M=Pb, Sn, Hg, Tl

What' s Organometallic Compounds?

A carbon-metal bond

Carbanions

(负碳离子)

Sodium acetylide

Sodium ethoxide

The natures of C-M bonds

The electronegativity of

the metal


Chapter 10 organometallic compounds

Solvents:

Ether

Hydrocarbon:

Pentane, Hexane

10.2 Preparation of Organolithium and

Organomagnesium compounds

Alkyl halide

Diethyl ether

Et2O

Tetrahydrofuran

THF

(四氢呋喃)

Anhydrous!

Butyllithium

(80% -90%)

Butyl bromide


Chapter 10 organometallic compounds

Grignard reagents: Alkylmagnesium Halides

V. Grignard and

P. Sabatier

1912 Nobel Prize

Phenylmagnesium

Bromide (95%)

Phenyl bromide

  • Characteristics of the reactions:

  • Alkyl groups: 1°, 2 °, 3 ° alkyl,

  • cycloalkyl alkenyl, aryl

2. Reactivity:

P223,7.4

Ch.P185(3)

Alkyl > Alkenyl or Aryl

RI > RBr > RCl > RF

3. Without substitutes:

4. Exothermic


Chapter 10 organometallic compounds

Grignard found that, in the presence

of ether, magnesium reacts with

alkyl and aryl halides at room

temperature to form organo-

magnesium compounds. These

solutions,called "Grignard reagents"

react with most functional groups

in a synthetically useful way.

For this discovery, tremendously useful

in laboratory and industrial synthesis,

he was awarded the 1912 Nobel Prize

in Chemistry(shared with

Paul Sabatier,discoverer of catalytic

hydrogenation).

François Auguste

Victor Grignard

1871-1935

http://www.nobel.se/chemistry/laureates/1912/grignard-bio.html


Chapter 10 organometallic compounds

Conjugate acid

Conjugate base

10.3Carbanions as Brøsted bases:

Acidity of hydrocarbon:

The stronger the acid is, the weaker

the conjugate base is.


Chapter 10 organometallic compounds

To different kinds of carbanions:

1)

3 °

>

>

>

> CH3

2) sp3 > sp2 > sp

To different element:

basicity of anions

decrease from left

to right in the

same period

The basicity decreases in order

Basicity of anions:

Carey(4th):

547


Chapter 10 organometallic compounds

tert-Butyllithium

tert-Butane

Ethoxymagnesium

bromide

Phenylmagnesiun

bromide

Organolithium compounds and

Grignard reagents as base:

Ch. P186

R-M reacts with much weaker acid

than H2O


Chapter 10 organometallic compounds

P296,

9.10

10.4.1 Synthesis of alcohols using

Grignard reagents

Reactions with carbonyl compounds:

  • Grignard reagents react with

  • Formaldehyde(甲醛 ) — Primary alcohols:

B. Grignard reagents react with

higher aldehydes— secondary alcohols:


Chapter 10 organometallic compounds

C. Grignard reagents react with ketones

— Tertiary alcohols:

Example:

Synthesis of Acetylenic alcohols (炔基醇):


Chapter 10 organometallic compounds

E. J. Corey

(1990 Nobel Prize)

Problem: suggest two ways

To prepare

前体

目标分子

10.4.2 Retrosynthetic analysis(逆合成分析)

Target

Molecule

Precursors

n-BuMgX + CH3COCH3

n-BuBr + Mg


Chapter 10 organometallic compounds

which changed the way organic

chemists undertake the synthesis

of complex natural products,

the synthesis of longifolene,

maytansine, the ginkolides,

prostaglandins and leukotrienes,

the development of new synthetic

methods, particularly using chiral

catalysts, and the application of

computers to synthesis design are

among his most notable achievements.

Corey has received many honors,

including the Wolf Prize (1986), the National

Medal of Science (1988), the Japan Prize

in Medicinal Science (1989) and the Nobel

Prize in Chemistry (1990).

Born in Massachusetts, Corey obtained

the Ph.D. at M.I.T. (1951), was on the

faculty at the University of Illinois

(1951-59) where he became full professor

at the early age of 27, and since 1959 he

has been professor at Harvard. His

research associates (graduate students and

postdoctoral fellows) number over 500

and populate the academic and industrial

laboratories of Europe, Asia and the

Americas.

Elias James Corey

1928-

Professor Corey (to collea-

Gues and friends, E.J.) is

known for his many spectacular

contributions to synthetic

organic chemistry. The concept

of "retrosynthetic analysis",


Chapter 10 organometallic compounds

Alkyllithium Cu (I)

halides

Lithium

dialkylcuprate

Lithium

halide

CuX

RLi

RLi

RCu

R2Cu- Li +

10.4.3 Alkanes synthesis by using

organocopper reagents

Ch.P185

(3)

Preparation of lithium dialkylcuprate reagents:

Coupling reactions of Organocoppers with

Alkylhalides


Chapter 10 organometallic compounds

Lithium

dibutylcuprate

Iodobenzene

Butylbenzene

(75%)

Characteristics of the reaction:

  • SN2 reaction

  • The order of the reactivity :

  • CH3 > 1°> 2°> 3°

  • I > Br > Cl > F

2. To alkyl halides, R: primary,vinyl and

aryl groups.

To Lithium dialkylcuprate,

R’: primary group or -CH3.


Chapter 10 organometallic compounds

12.44 Ziegle-Natta Catalysis of Alkene

Polymerization

Carey:P567

14.15

Ziegle catalyst: TiCl4-Et2AlCl

Ethylene Ethylene oligomers

  • Characteristics of the products:

  • Ethylene oligomers with 6-18 carbons

  • High-density

Isotactic polypropylene

等规 (立构) 的聚丙烯

G. Natta’s contributions:


Chapter 10 organometallic compounds

Coordination polymerization

配位络合聚合

Polypropylene industry was started

K. Ziegle and G. Natta shared

the 1963 Nobel Prize in Chemistry


Chapter 10 organometallic compounds

Problems: Carey(4th)P573

14.28 (b)

14.29

14.15 (b), (d)

14.17 (h), (m), (n)

14.18 (d), (e)

14.19 ((b), (f)

14.20 (d), (e)

14.21 (a)-(c)

14.22 (b), (f), (g)

14.23

14.25

14.26*(选作)

14.27


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