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प्रश्न
Explain the following reactions:
Stephan reaction
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उत्तर
This reaction is used to synthesize aldehydes from nitriles or cyanides. Firstly, nitriles or cyanides are reduced in presence of stannous chloride and hydrochloric acid in ethyl acetate solvent to form imine intermediate. Then hydrolysis of this intermediate with water gives the corresponding aldehyde.
\[\ce{CH3 - C ≡ N + 2[H] ->[SnCl2/HCl][Ether] CH3 - CH = NH + HCl ->[H2O/H^+] \underset{Acetaldehyde}{CH3CHO} + NH4Cl}\]
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संबंधित प्रश्न
Write the structure of the product of the following reaction:
Aldehydes are produced on reduction of the following by DIBAL-H:
Match the example given in Column I with the name of the reaction in Column II.
| Column I (Example) |
Column II (Reaction) |
||
| (i) | \[\begin{array}{cc} \phantom{...}\ce{O}\phantom{..............................}\ce{O}\phantom{}\\ \phantom{...}||\phantom{..............................}||\phantom{}\\ \ce{CH3 - C - Cl + H2 ->[Pd - C/BasO4] CH3 - C - H} \end{array}\] |
(a) | Friedel Crafts acylation |
| (ii) |  |
(b) | HVZ reaction |
| (iii) |  |
(c) | Aldol condensation |
| (iv) | \[\begin{array}{cc} \ce{R - CH2 - COOH ->[Br/Red P] R - CH - COOH}\\ \phantom{.....................}|\\ \phantom{.......................}\ce{Br} \end{array}\] |
(d) | Cannizaro’s reaction |
| (v) | \[\ce{CH3 - CN ->[(i) SnCl2/HCl][(ii) H2O/H+] CH3CHO}\] | (e) | Rosenmund’s reductio |
| (vi) | \[\ce{2CH3CHO ->[NaOH] CH3 - CH = CHCHO}\] | (f) | Stephen’s reaction |
An alkene ‘A’ (Mol. formula \[\ce{C5H10}\]) on ozonolysis gives a mixture of two compounds ‘B’ and ‘C’. Compound ‘B’ gives positive Fehling’s test and also forms iodoform on treatment with \[\ce{I2}\] and \[\ce{NaOH}\]. Compound ‘C’ does not give Fehling’s test but forms iodoform. Identify the compounds A, B and C. Write the reaction for ozonolysis and formation of iodoform from B and C.
The reaction
When 2 – hydroxyl benzoic acid distilled with zinc dust, it give
The general formula CnH2NO2 could be for open chain
The intermediate compound ‘X’ in the following chemical reaction is:
The reaction of benzene with CO and HCl in the presence of anhydrous AlCl3 gives ______.
An organic compound with molecular formula \[\ce{C7H7NO2}\] exists in three isomeric forms, the isomer ‘A’ has the highest melting point of the three. ‘A’ on reduction gives compound ‘B’ with molecular formula \[\ce{C7H9N}\]. ‘B’ on treatment with \[\ce{NaNO2/HCl}\] at 0-5° C to form compound ‘C’. On treating C with \[\ce{H3PO2}\], it gets converted to D with formula \[\ce{C7H8}\], which on further reaction with \[\ce{CrO2Cl2}\] followed by hydrolysis forms ‘E’ \[\ce{C7H6O}\]. Write the structure of compounds A to E. Write the chemical equations involved.
