Carboxylic Acids 2

Question 1

Ester Outline

Answer 1

Carboxylic acid derivative (reaction with alcohol). Trigonal planar gemotery (C to C bond angles = 120 degrees). Functional group C(double bond)O(single bond) OH

Question 2

Ester Synthesis

Answer 2

Carboxylic acid and alcohol react (in the presence of a strong acid catalyst) to form ester and water. (reversible reaction in presence of strong acid catalysts. Reaction happens at equilibrium)

Question 3

Base Hydrolysis of Esters (Saponification) Outline

Answer 3

Fatty acids (esters) to soap (carboxylic acid derivative). Steps: OH- nucleophilic attack of ester (rate determining, depends on base strength), tetrahedral deterioration and proton transfer. Note isn’t based catalysed as OH- is used up in reaction

Question 4

Tetrahedral Intermediate Deterioration OutlineOutline

Answer 4

Tetrahedral intermediae is unstable due to negative charge on O. O in OR substituent donates electrons (severing it’s bond) to C. OR leaves (alkoxide) and double bond is formed between C and O.

Question 5

Proton Transfer Outline

Answer 5

Negatively charged alkloxide (on O) causes tetrahedral donation of H from OH. positive ions from alkoxide attaches to tetrahedral and H attaches to alkloxide

Question 6

Non-hydrolysable fatty acids

Answer 6

Steroids, fatty acids and eicosanoids

Question 7

Triglycerides Outline

Answer 7

Both animal and plant sourced. 11-19 Cs in hydrocarbon chain. Glycerol attached to 3 fatty acids. Simple (all fatty acids are the same) and complex (2+ different fatty acids)

Question 8

How to tell the difference between animal and plant fat sources

Answer 8

Animal = solid at room temp. Plant = liquid at room temp. Animal has a higher melting point (more Cs = higher melting point)

Question 9

Molecule packing outline

Answer 9

Way to differentiate animal (pack well) and plant (pack poor) fatty acids.S traight chain fatty acids of 1 molecule are placed next to hydrophobic chain of another (no intercations). Plant fatty acids have kinks in their hydrocarbon chains (less Van der Waals) making their shape irregular

Question 10

How does shortening the hydrocarbon chain increase melting point of margarine

Answer 10

Shorter chain = less unsaturated bonds

Question 11

What are phospholipids hydrolased to

Answer 11

glycerol with 1 phosphoric acid derivative and 2 carboxylic acids

Question 12

Cholesterol Outline

Answer 12

cell membrane component, synthetic steroid/bile acid/salt precursor

Question 13

Steroid structure

Answer 13

3 cyclohexanes and 1 pentohexane rings. Variation occur in substituent type and location

Question 14

Cholesterol in cell membranes outline

Answer 14

1 cholesterol molecule/phospholipid. Decreases permebility of hydrophilic molecules and fortifies structure. Cell membranes without cholesterol have cell walls