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Sunday, January 19, 2020

Why enol form of Beta Dicarbonyl compound more stable than those of monocarbonyl compounds?


Enol form of Beta Dicarbonyl compounds are more stable because it has a conjugated π-system and intramolecular H-bonding.

Why enol form of phenol is more stable than its keto isomers?

Enol form of Phenol is more stable than keto form because it has a stable aromatic ring.

Which of the Complex of the following pairs has the highest value of CFSE?

(1) [Co(CN)6]3-  and [Co(NH3)6]3+
(2) [Co(NH3)6]3+ and [CoF6]3-
(3) [Co(H2O)6]3+  and [Rh(H2O)6]3+
(4) [Co(H2O)6]2+ and [Co(H2O)6]3+

SOLUTION:
(1)  CN is the stronger ligand than NH3 therefore CFSE of [Co(CN)6]3-  will be more than  [Co(NH3)6]3+
(2) NH3 is stronger ligand than F therefore CFSE of [Co(NH3)6]3+ will be more than [CoF6]3- .
(3) Co belong to 3d series whereas The Rh belong to 4d series. More the value of n more is CFSE therefore CFSE of  [Rh(H2O)6]3+  is more than [Co(H2O)6]3+ .
(4) Oxidation number of Co in [Co(H2O)6]3+ is more than the Oxidation number of [Co(H2O)6]2+  therefore, CFSE of [Co(H2O)6]3+ is more than  [Co(H2O)6]2+ .


Related Questions:

(1) Why all the tetrahedral Complexes are high spin Complexes?

(2) Why Fe(CO)5 is colourless while Fe(bipy)(CO)3 is intensely purple in colour ?

(3) Why [Mn(H2O)6]+2 is colourless although in which Mn+2 ion had five unpaired electrons ?

(4) Why [FeF6]3– is colourless whereas [CoF6]3– is coloured

(5) Why [Ni(CN)4]-2 is colourless while [Ni(H2O)4]-2 is colour although both have +2 oxidation state and 3d8 configuration ?

Friday, January 17, 2020

How can explain resorcinol (1,3-Dihydroxybenzene) give positive Iodoform test?


Resorcinol (1,3-Dihydroxybenzene) give positive iodoform test because it is in equilibrium with its tautomer cyclohex-2-en-1,5-dione. It give 3, 5-dioxohexanoic acid (CH3-CO-CH=CH-CH2-COOH) on reaction  with strong base (OH-) (I2+NaOH Iodoform reagent) ,which has a CH3-CO (acetyl) group, so it’ clear that it would be give positive iodoform test.

Related Questions:
How can explain that 1, 3, 5-Trihydroxybenzene give positive iodoform test?

How can explain that 1, 3, 5-Trihydroxybenzene give positive iodoform test?

1,3,5-trihydroxybenzene give positive iodoform test because it is in equilibrium with its tautomer cyclohexane-1,3,5-trione. It give 3,5-dioxohexanoic acid (CH3-CO-CH2-CO-CH2-COOH) on  reaction  with strong base (OH-) (I2+NaOH Iodoform reagent) ,which has a CH3-CO (acetyl) group, so it’ clear that it would be give positive iodoform test.