Organic Name Reactions Reagents and Molecular Rearrangements

Name reactions are a very important concern in organic chemistry. Name reactions in organic chemistry and the corresponding mechanisms are nevertheless fascinating for their far reaching utility as well as their insight into organic reactions. Furthermore, understanding their mechanism greatly enhances our ability to solve more complex chemical problems.

In the organic molecular rearrangement reaction, the molecular skeleton is altered – that is, the sequence in which atoms are attached is changed. These reactions may also include other changes in the molecule; for example one functional group may be converted into another. For example, Benedict’s test is performed under mildly basic conditions. The reagent reacts with all reducing sugars to produce the red precipitate copper (I) oxide.

Fries Rearrangement in Organic Chemistry

Fries rearrangement involves the conversion of phenolic esters on heating in the presence of aluminum chloride to hydroxy ketones. If an ester of a phenol is heated with aluminum chloride, the acyl group migrates from the phenolic oxygen to the ortho or para position on the ring. Fries rearrangement favors both ortho and para isomer of acetophenone.

The mechanism of Fries rearrangement is not certain. Generally, low temperature favors the formation of the para isomer, whereas high temperature favors the formation of ortho isomer. There is evidence for an intermolecular mechanism, but it has recently been shown that the rearrangement is at least partly intermolecular. It would appear that the mechanism is best regarded as a combination of the two mechanisms occurring at the same time.

Is Benedict’s test Qualitative or Quantitative?

Benedict’s test is a qualitative and quantitative test, which is more sensitive to reducing substances than the single copper reduction test.

Benedict’s test determines whether a monosaccharide or disaccharide is a reducing sugar. To give a positive test, the carbohydrate must contain a hemiacetal that hydrolyzes the aldehyde form in an aqueous solution. Benedict’s reagent is an alkaline solution composed of cupric ions, which oxidize the aldehyde into a carboxylic acid. The cupric ions, in turn, are reduced to cupric oxide which forms a red precipitate.

RCHO + 2Cu2+ + 4OH à RCOOH + Cu2O + 2H2O

Thus, organic named reactions and their strategic principles are used in the synthesis of complex natural and unnatural products.

 

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