Riemer Tiemann reaction

              Reimer Tiemann reaction 

Table contents:

History

About reaction

Mechanism

Comparasion

!>

History-

Riemer Tiemanm reaction is discovered by karl reimer ( 1845-1883 ) and Ferdinand Tiemann ( 1856-1883 ).

About reaction-

Riemer Tiemann reaction is substitution reaction . This reaction used for the orthoformylation of phenols.

When phenol is treated with chloroform in the presence of sodium hydroxide,an aldehyde group introduced at the ortho position. The reaction is called reimer tiemann reaction.

Mechanism-

1.Deprotonation of chloroform in the presence of strong base ( sodium hydroxide) 

And now chloroform carbanion forms.

2.chloroform carbanion undergoes alpha elimination and now dichlorocarbene formed as product.

3.sodium hydroxide deprotonates the phenol reagent.

4.Negative charged is delocalized into the benzene ring.

5. Nucleophile attack on the dochlorocarbene, forming an intermediate chloromethyl substituted phenol.

6.Finally we achieve hydroxy benzaldehyde.

👉👉 Phenol is converted into hydroxy benzaldehyde via chloroform.Carbene is highly electron deficient due to electron withdrawing nature of its two chlorine group.

Comaparasion to other methods-

Directly we can formylation of aromatic compounds bh various method such as the gattarmann reaction, gattarman koch reaction, and Duff reaction, haak reaction but the safety of reaction the Reimer Tiemann reaction is the most advantage routine in chemical synthesis.

➡️ Riemer Tiemann reaction can be useful to yield phenolic acids by carbon tetrachloride product will be salicylic acid rather than the salycyladehyde.

friedal craft reaction and mechanism

                  Friedal-craft reaction

Table contents:

History

About reaction

Mechanism

Advantage

Limitations

Example

History-

Friedal craft reaction is discovered by charles friedal ( french scientist ) and james crafts ( American chemist ) in 1877.

About reaction-

Frieda crafts reaction is an electrophilic aromatic substitution reaction including organic coupling reaction. Friedal craft reaction are two type:

-Frieda craft alkylation

-Frieda craft acylation

This reaction involves the replacement of hydrogen atom via an electrophile.

The reactant for this reaction is aluminum trichloride, it is acts as Lewis acid and it is used in generating an electrophile in the process.

👉 Friedal craft alkylation:

This reaction helps in generating alkyl banene via alkyl halide as reactants. The catalyst is aluminum trichloride. Friedal craft alkylation indicate the replacement of an aromatic proton with an alkyl group.

In this reaction carbocation will be generate as intermediate.

Mechanism:

1.The formation of carbocation using Lewis acid aluminium trichloride.

2.Carbocation attack on the aromatic ring.

3.deprotonation of the intermediate will be. And the proton goes to on hydrochloric acid, regenerating aluminium trichloride catalyst.

👉 Frieda craft acylation:

It is the acylation of the aromatic rings, in this reaction involves the addition of the acyl group to aromatic ring. In this reaction reactant is the acid chloride and the catalyst is aluminium trichloride.The reaction is between benzene and acyl chloride under the condition. Lewis acid generate a highly electrophilic acylium kon which is stabilized by resonance.

Mechanism:

Step 1. Forming of acylium ion.

Step 2. Acylium ion attack on the aromatic ring and the aromaticity of the ring.

Step 3. Intermediate complex is deprotonated.

Step 4. Ketone product is formed adding water.

Advantage:

Acylation and alkylation are the advantage of friedal craft reaction.

Limitations:

Friedal craft reaction's limitations are carbocatiom rearrangement and polyalkyaltion . Acylation reaction yields only ketones.  Aryl amines can not be formed in this reaction.

Example

Download Now href="https://lh3.googleusercontent.com/-pYFxuXtXFKY/YJdEW4HSWGI/AAAAAAAAATs/VH750eG0lxwoHDAKqFSKZ32vSjH1kLnvgCLcBGAsYHQ/s1600/1620526165882827-5.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;">

Sandmayer Reactions , mechamism , example , uses

                       Sandmayer reaction

-Table of contents

: History

: About reaction

: Mechanism

:Uses

: Frenquely asked questions

: Example

-History

Traugott sandmayer ( swiss scientist ) discovered sandmayer  reaction in 1884 

during experiment to synthesize polyacetylene from benzene diazonium chloride and cuprous acetylide.

The product was phenylchloride of the Mr.sandmayer's reaction.

Reactant -aromatic amine

product  - arylhalide

Intermediate- nitrosamine

Reaction type - Radical nucleophilic aromatic substitution

Sandmayer reaction is the substitution reaction of an aromatic amino group.This substitution will be via nucleophile, proceed under Cooper catalysis.

Sanmayer reaction is used in the production of aryl halide.

It is used to transformation on benzene ( hydroxylation,trifluoromethylation,cynation, and halogenation )

-Mechanism

1.Formation of nitrosonium ion

2.Benzenediazonium formation 

Formation of nitrosonium ion

-at first we take sodium nitrate and acid 

-then water is removed in reaction

-nitrosonium ion reacts as an electrophile and it is reacted with an heterocyclic amine to form diazonium salt.

Benzenediazonium ion formation

-amine and nitrosonium ions will make benzenediazonium ion.

Uses:

-one important use is formation of an aryl halide

-It is used as synthesis of chloroform,iodoform etc.

Frenquely asked questions:

1.what type of sandmayer reaction?

 Ans: substitution reaction

2. Difference between sandmayer and gattarman reaction !

 Ans: In sandmayer reaction reactant is CuCl in HCl but in gattarman reaction reactant is CuCl or CuBr in chlorobenzene.

3.What is importance of sandmayer reaction?

 Ans: sandmayer reaction is important for transformation of benzene.

4.what is use of CuCl in sandmayer reaction ?

 Ans: It is react like nucleophile.

Example:

http://adzmoney.linkyqueen.ga/tracking/html.php?uid=2554&sid=2897