Clemmensen reduction: reduction of an aldehyde or a ketones with zinc amalagam and concentrate Hydrochloric (HCl) acid.

Note; Clemmensen reduction not  suitable for those compound having acid sensitive groups ( basic in nature) such as  Alcohol, amines, alkenes, ester, cyclic ketal, nitro etc.

In The Cannizzaro, The intermediate That will be The best hydride donor is:

Ans (3) Dioxide anion is a better hydride doner, and presene of -OCH3, group further increases the electron density.

Note: Dioxide anion form in cannnizzaro reaction when concentration of Base  taken high  and the reaction becomes 4rth order reaction.

Abnormal Behaviour of Water and maximum density at 4 degrees why? Number of Hydrogen bonds in Water (Ice) molecules? Why ice Float in water ?

In Ice (solid water), the oxygen atom of each H₂O molecule is surrounded by 4 hydrogen atoms
 

Two hydrogen atoms attached by covalent and remaining Two hydrogen atoms attached by inter molecular hydrogen bonding.

Hydron bond In Water Molecule:

Due to hydrogen bonding in ice ,water molecules are arranged in the form of cage in which water molecules are tetrahedrally attached to four other water molecules.

Each oxygen atom forms four bonds out of which two are normal covalent bonds and two are hydrogen bonds.

Why ice Float in water ?

Hydrogen bond is longer than the normal covalent bond; thus, there are a large number of vacant spaces. Due to this open cage-like structure, volume becomes more and density becomes less. and hence water float in water.

Why water has maximum density at  4°c ?

When ice is heated From 0°c to 4°c, the number of hydrogen bonds are broken and water molecules come  close to each other  to fill up the vacant space. 

There will be the contraction of volume as well as expansion, due to temperature rise but the effect of contraction is dominant over the effect of expansion from  0°c to 4°c.

Hence the resulting volume decreases and  density increases and becomes maximum at 4°c.

Water  density beyond  4°c :

When H₂O is further heated beyond 4°c the effect of expansion is dominant over the effect of contractions and density decreases beyond 4°c.

Choral (CCl3CHO) has no alpha hydrogen but can not give cannizzaro's reaction ?

 

When Chloral Boiled with NaOH gives Haloform Reaction. Here CCl3 (-)  group is Very Good Leaving group hence cannizzaro not possible 

CANNIZZARO REACTION: DISPROPORTIONATION:

(1) Introduction:

(2) Mechanism:

(3) Condition for cannizaro reaction:

(4) Illustrative Examples

(5) Crossed Cannizzaro reaction

(6) Intramolecular cannizaro reaction:

Arrange the following as decreasing order of dipole moment of Chlorine derivatives of Methane Molecule?

As no. of C-Cl bonds increases the net dipole moment decreases.

CH 3Cl > CH2Cl2 > CHCl3 > CCl4 . 

Related Questions:

(1) The Dipole moment of Chloromethane is more than Fluoromethane. Explain.

(2) CO2 has got dipole moment of zero why?

(3) Dipole moment of CCl4 is zero while that of CHCl3 is non zero. explain.

(4) Compare the dipole moment of H2O and F2O.

(5) Which has more dipole moment of NH3 or NF3?

(6) Which NH3 and NF3 have the highest dipole moment and why?

(7) Why dipole moment of NH3 is lower than NH3?

(8) What is the difference of dipole moment of NH3 and NF3 respectively?

(9) Among CH3OH, CH4, CF4, CO2 and CH3F, which has the highest dipole moment?