Chapter 10 reactions

Making grignard reagents

Reagent Mg

Added to: R-X

ethers need to be present

Starting product R-X

End product R - MgX

Organolithium reactions

Reagent 2 Li

React the same like gringards

Starting product : R-X

End: Li - R and X- LI

Making alcohol using organometallics (MgX)

reagent: R-MgX

need and ether

1. R adds to the product

2. the double of O is released

3. H30 is added to make alcohol

Depending on how many R were to the original product being added you can make 1,2,3 alcohols

Ester

R - C (=O) - OR

organometallic with ester (R-Mgx)

Reagent: R-MgX

Product being attacked : Ester (R - C (= O) - OR )

End product : (3) tertiary alcohol with 2 identical alkyl group

Mechanism

1. the organometallic (R- MgX) attacks the carbon and double bond breaks

2. the intermediate: the OR group leaves and the O becomes a double bond again forming a keton

3. Another R - MgX comes in and add an R and the double bond with O breaks

4. H30 comes in and make the O into a OH

organometallic with Acid chloride (R-Mgx)

Reagent: R-MgX

Product being attacked : acid chloride → R - C ( = O) - X

x= Cl , Br, I

End product : (3) tertiary alcohol with 2 identical alkyl group

Mechanism

1. the R from R- Mgx attacks the acid chloride and causes the double bond with O to break

2. X halide leaves and causes the O to go back to a double bond and this forms a keton

3. Another R-MgX comes in and the R attacks the carbon again cause the double bond with O to break

4. H3O comes in and make O → OH

Addition to ethylene Oxide

• both grignard and lithium reagent attack epoxides and opens them

REACTION IS USED: to extend the length of carbon chain by two carbon

Reagent: R -MgX

mechanism:

1. the R from R -MgX attacks the carbon and that cause the epoxide ring to open

2. so there is one carbon connected to a R group the Other Carbon connects to the O

3. H3O is added to make O a OH

Limitation or Organometallics

Gringards are good nucleophile but present in acid its strong base

Ex: OH,NH,SH

In the presence of multiple bond with strong electronegative element it will be a nucleophile

ex: C=O , C = N

Reduction Of Carbon

Reagents used NABH4 and LiALH4

• this is used to add hydrogen instead of R goups

Hydride reduction with Sodium borohydride

Only reacts with Ketones and aldehydes

Reagent: NaBH4

works in the presence of a acid (H3O) or Ester (R - C (=O) - OR)

Mechanism:

1. the H from the BH4 acts like a hydride and adds the H to the Carbon of the aldehyde or keton

2. the Double bond of O breaks

3. H30 comes in an give a H to O to make OH

Lithium Aluminum Hydride

Reagent: LiAH4 or LAH

• stronger reducing agent, dangerous to work with

WORKS WITH: all of them, Aldehyde, Ketone, Ester , Acid (anion)

But it is easier to reduce with Ester , Acid (anion)

Works the same like Sodium borhydride for aldehyde and ketone but with ester and acid it works different:

Mechanism

1. the H from the LiAH4 adds to the carbon

2. the double bond with O breaks

3. the OR leaves, or the strongest lG leaves

4. the double bond of O is formed

5. Another LiAH4 comes in gives a hydrogen again and the double bond with O breaks

6. H30 comes in and makes O into OH

Catalytic hydrogenation

Reagent : raney Ni

more reactive than Pd,PT catalyst

Hydrogen and ranny ni reduces ketons alkenes, alkyne