RPA - CA and Esters Flashcards
why are carboxylic acids soluble in water?
The polar water and oxygens form hydrogen bonds with other molecules (dimers)
What happens to carboxylic acid solubility as chain length increases? Why
Solubility decreases as the aliplatic (hydrophillic) part is longer compared to the hydrophillic end
Which part of ester group makes up the parts of the names?
alcohol gives the aklyl group, e.g. ethyl, the acid gives the rest e.g. ethanoate.
What does a carboxylic acid react with? Give an equation for each one
Reactive metals e.g. Na
Bases - e.g. NaOH
Carbonates - e.g. NaCO3
Give two uses of esters
flavourings, perfumes
What are the two ways in which an ester can be hydrolyzed?
By acid - acid catalyst by reaction with water
By alkali - reacts with acid to produce conjugate base of acid plus alcohol
In triglycerides, what is is easy to forget?
The ester linkage. make sure there is the correct functional group on the end of the fatty acid chains
What is the trend in boiling points of fatty acids as chain length increases?
Boiling point increases
What is the difference between a simple and mixed triglyceride?
Mixed has differing fatty acid chains, simple has three identical
Give three sources of saturated fats
butter, biscuits, cake.
Give a physical characteristic of saturated fats
Solid at RTP
What are the two types of unsaturated acid, which one is bad, and why?
Trans - bad - stacks just as well as saturated
cis - good - stacks poorly due to shape => weaker VdW forces
Give a source of cis-unsaturated fats
fish
If you are given the shorthand 16:0 for a fatty acid, what do the two numbers represent?
16 carbons, no C=C bonds
What is the full name of (18:2)(9,12)
Octadeca-9,12-dienoic acid
What is an acid anhydride made from?
2 molecules of carboxylic acid dehydrated to form -O- bond between two molecules
What are the conditions for making an ester from COOH and OH?
Reflux, 80 C, H2SO4
What is a disadvantage of the COOH/OH reaction for making esters industrially?
Equilibrium, so low yield
What are the conditions for the reaction of alcohol with acetic anhydride?
gentle heating
What is an advantage of OH/anhydride reaction for industrially producing esters?
non-reversible, so 100% yield
What are the products when ethanoic anhydride reacts with methanol?
Methyl ethanoate + ethanoic acid.
What are the products with propanoic anhydride reacts with ethanol?
Ethyl propanoate + propanoic acid
In acid hydrolysis, what does the acid act as?
Catalyst
In base hydrolysis, what does the base act as and what is formed?
Base is a reactant, the salt of the carboxylic acid is formed.
What is biodiesel?
Methyl or ethyl ester of long chain carboxylic acid (fatty acid) produced by transesterification of triglycerides
What are triglycerides?
Esters of glycerol and three fatty acids
What is the catalyst for biodiesel synthesis?
NaOH/KOH
What is transesterification?
Exchange of one alcohol for another in an ester
