Hydrolysis of Sucrose

Hemiacetal and acetal. Mutarotation

Mutarotation→ the inter conversion of alpha and beta anomeric forms of glucose in solution. glucose exists as a mixture of 36% alpha and 64% beta anomeric forms in solution

Hemiacetal and acetal

Hemiacetal. Central carbon with R group OR H and OH

Hemiketal central carbon with 2 R one OR and OH

Acetal central carbon with R group two OR and H

Look at the diagrams on ppt

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Optical rotation

The instrument that is used for transforming u polarized light to plane polarized light (PPL) is called polarimeter

Dextrorotary rotates PPL clockwise

Lego rotary rotated PPL counterclockwise

D-glucose is dextrose bc rotates clockwise

D-fructose is levulose bc rotates counterclockwise

Polarimeter components

1) light source (usually from a sodium lamp)

2) polarizer (Nicol prism) which transmits only those light waves having their electric field components in the same plane. This is PPL

3) Tube for holding the optically active substance in the light beam

4)Analyzer- The observed rotation alpha is measured by using another moveable Nicol prism must be oriented at same angle alpha as first in order to transmit the light beam

5) eye piece

Énantiomorphes

enantiomers rotate light in opposite directions, but the same number of degrees

Clockwise or d (+). Counterclockwise or l (-)

DIRECTION OF ROTATION OF LIGHT NOT LONKED TO R OR S (D or L)

Invert sugar

Why is sucrose called invert sugar and sucrose called invertase

Sucrose (+66.5) hydrolysis to glucose (+52.7) and fructose (-92), there us inversion of optical rotation from dextrorotary to Levorotary that is the hydrolysis mixture (glucose and fructose(-20.6) of sucrose has an optical rotation that is the opposite of sucrose

Page 3 eq 6

m(slope)= -k1/2.303. K1=-2.303

Since k1=k2 (H30+)

K2=k1/(H3O+)=-2.303m/(H3O+)

Page 4 point 4

Reaction rate of alpha(sucrose)→ pseudo 1st order reaction

Rate of change of optical rotation with time will be greatest early in the reaction because (sucrose) is high at the start of the reaction; higher the (sucrose) greater is the rate of hydrolysis

As hydrolysis proceeds, (sucrose) decreases and rate of hydrolysis also decreases; rate of change of optical rotation with time will also decrease

Page 5

D sucrose rotates PPL clockwise (right) it is dextrorotary (d/+)

Alpha plus Bêta equals one equation