Hydrogenation

Question 1

How is measured the catalyst activity?

Answer 1

Measure of the time required to hydrogenate soybean oil from iodine value of 120 to an iodine value of 80 at 350˚F, 20 psig and 0.05 catalyst

Question 2

True or false : hydrogenation under low amount of hydrogen leads to more trans formation

Answer 2

true

Question 3

T or F :If you want to decrease the trans content when doing hydrogenation, you can increase the pressure and agitation

Answer 3

True

Question 4

What are the two factors you can do to decrease trans formation in hydrogenation

Answer 4

increase pressure and agitation

Question 5

Why is there trans fat made during hydrogenation?

Answer 5

When there is not enough hydrogen for the complete hydrogenation. Also, there is trans fat made because of reaction rate of oleic to steraric is smaller than from linoleic to oleic.

Question 6

Why does low agitation and low hydrogen pressure leads to more trans fatty acid in hydrogenation

Answer 6

because lower amounts of hydrogen can leads to reformation of the double bond in the FA

Question 7

The melting point of elaidic acid is _____ higher than oleic acid

Answer 7

30˚C

Question 8

What is the catalyst of the hydrogenation?

Answer 8

nickel catalyst in the divided state

Question 9

What are the variables that affct the hydrogenation

Answer 9

1. Temp
2. Pressure
3. Agitation
4. Catalyst

Question 10

What are the two things that can result of hydrogenation

Answer 10

positional isomerism

geometric isomerism

Question 11

What is the main reason of fats becoming plastic during hydrogenation ?

Answer 11

the change in cis to trans.

Question 12

T or F : trans FA are unatural

Answer 12

true, but they can be found in natural sources because of the microorganisms present (example in milk, from microorganisms in the rumen).

Question 13

T or F : Stearic acid is produced 12x faster from linoleic acid than from oleic acid

Answer 13

true

Question 14

What is the reason why some nutrition label contains canola oil and other cheap oils?

Answer 14

because these oils are cheap and are used to has a base for modification. The oil base doesn’t matter because the process will create consistant physical properties.

Question 15

T or F : one mole of iodine will react with one mole of double bonds

Answer 15

true, because one iode for each carbon of the double bond,

Question 16

What is wandering?

Answer 16

positional isomerism that occurs during the hydrogenation

Question 17

Why is there an accumulation of oleic acid during the hydrogenation?

Answer 17

because of the selectivity ratio. Stearic acid is produced 12 faster from linoleic than from oleic acid.

Question 18

When we say that the selectivity ratio is 12 (C18:2/C18:1) what does this implies?

Answer 18

This implies that the conversion of oleic to stearic takes 12 times more time than the conversion of linoleic to oleic.

Question 19

T or F : if we could find a way to have complete hydrogenation, the trans wouldn’t be a problem

Answer 19

true.

Question 20

What are the critical steps in controlling the degree of isomerization and seletivity or reactions?

Answer 20

adsorption and transfer/diffusion

Question 21

What is transfer and diffusion?

Answer 21

Transfer : the transfer of the reactants from the bulk of the oil to the catalyst surface
diffusion : the diffusion of the reactants from the surface of the catalyst through the pores.

Question 22

T or F : when a double bond is located at the carbon 9, the positional isomerism during hydrogenation can bring the double bond at carbon 7

Answer 22

true

Question 23

T or F : When there is positional isomerism, the tendency is that the new double bond has more chances to be a trans double bond

Answer 23

true

Question 24

What are the two types of hydrogenation

Answer 24

partial and complete

Question 25

T or F : the majority of the double bonds formed will be in the trans form during partial hydrogenation

Answer 25

false (42% will be in the trans from)

Question 26

Complete : If you want high levels of monounsaturated, you’ll need a _____ catalyst but if you want high levels of hydrogenation, you’ll want _____ catalyst

Answer 26

very selective

non-selective

Question 27

T or F : geometric configuration and chemical and physical characteristics of catalyst will determine selectivity.

Answer 27

true

Question 28

T or F : the hydrogenation of FA on the TG is not a function of their location

Answer 28

true