Organic Chemistry Reactions

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Organic Chemistry Reactions
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The Chugaev reaction allows the formation of olefins from xanthans.

 reaction chugaev 01

It is a pyrolysis reaction that is generally carried out in the temperature range between 100 and 250ºC.

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Organic Chemistry Reactions
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In 1899, Wagner and Brickner observed a regrouping when treating a-pinene with hydrochloric acid. This observation contradicted the classical theory that was based on the invariance of the skeleton of the molecule.  
In 1922, H. Meerwein established a cationic mechanism that explained the reaction. This mechanism occurs with the formation of a carbocation that undergoes a [1,2] rearrangement of hydrogen, alkyl or aryl groups.
 
wagner meerwein regrouping 01

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Organic Chemistry Reactions
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The Claisen condensation involves the reaction of esters [1] in a basic medium to form 3-ketoesters [2]

claisen-condensation.gif

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Organic Chemistry Reactions
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In 1981, Weinreb and Nahm obtained ketones by adding lithium or magnesium organometallics to N-methyl-N-methoxyamides.
Weinreb's amides are prepared from acid halides or anhydrides by reaction with N,O-dimethylhydroxylamine in the presence of base (pyridine).
 
weinreb synthesis 01
weinreb synthesis 02

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Organic Chemistry Reactions
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In this reaction two alkenes [1] and [2] are treated with a transition metal that acts as a catalyst, giving a mixture of alkenes [3] (including Z/E isomers).

This product is obtained by exchange of alkylidene groups.

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Organic Chemistry Reactions
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The Wharton fragmentation is a concerted reaction in which a leaving group is located in position 4 with respect to an electron donating group. The transfer of the free pairs of the donor group produces the fragmentation of the neighboring bond and the loss of the leaving group with the formation of double bonds. Let's see an example:

wharton fragmentation 01

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Organic Chemistry Reactions
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The tosylhydrazones of aldehydes or ketones [1] react with two equivalents of organolico generating an anionic intermediate [2] capable of undergoing alkylation processes.

 
shapiro-01.gif
 

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Organic Chemistry Reactions
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The Wharton synthesis allows α,β-epoxyketones to be transformed into allylic alcohols by treatment with hydrazine in acetic acid medium or hydrazine hydrate followed by strong base. The \alpha,\beta-epoxyketone is obtained from the \alpha,\beta-unsaturated ketone by oxidation with hydrogen peroxide in a basic medium.

wharton synthesis 01

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The Wacker oxidation allows the transformation of alkenes into the corresponding ketones by treatment with Pd in ​​the presence of copper salts. Copper has the ability to oxidize palladium(0) to palladium(II), the latter being the catalytic agent in the reaction.

wacker oxidation 01

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Organic Chemistry Reactions
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In 1902, Wolff observed that treating diazoacetophenone (α-diazoketone) with Ag 2 O/H 2 O produced a rearrangement that generated phenylacetic acid.

wolff regrouping 01

By replacing water with ammonia, phenylacetamide is obtained.

wolff regrouping 02