Carboxylic, esters, acyl Flashcards
What is the fucntional group of carboxylic acids?
-oic acid
COOH
What type of acid are carboxylic acids?
Weak - because they only partially disscoiate to into carboxylate ions and H+ ions.
How soluble are carboxylic acids?
- Very soluble - can form hydrogen bonds with each other and therefore they have high boiling points.
- the solubility of carboxylic acids decreases as the length of the carbon chain increases. (large COOH don’t dissolve in water)
- in liquid carboxylics, dimers form. ( two COOH bond)
How can carboxylic acids be formed?
- oxidation of primary alcohols and aldehydes. (potassium dichromate)
- Hydrolysis of nitriles
reflux the nitrile with dilute HCL and then distil off the COOH.
What can carboxylic acids react with to form salts?
Bases- COOH are neutralised by aqueous base (alkalis) to form salts and water. (lose a hydrogen)
What are the products when carboxylic acids react with carbonates?
Salt, carbon dioxide and water
What reducing agent is used to reduce a carboxylic acid?
LiAIH4 in dry ether.
How is an acyle chloride produced from a carboxylic acid?
Mix a carboxylic acid with phosphorous(V) chloride = acyl chloride
- gives steamy acidic fumes of hydrogen chloride
How are esters made form alcohols and carboxylics?
Esterification - heat a carboxylic acud with an alchohol in the presence of an catalyst, such as concentrated H2SO4 or HCL, you can get an ester.
How can you form ethyl ethanoate?
you reflux ethanoic acid with ethanol and concentrated sulfuric acid as the catalyst. Use distillation and collect the liquid that comes off just below 80 degrees. The product is then mixed with sodium carbonate solution to react any carboxylic acid left. The ethyl ethanoate forms a layer on the top of the aqueous layer and can easily be separated using a separting funnel.
How can esters be broken up?
Acid hyrolysis or Base hydrolysis
- Acid hydorlysis splits the ester into an acid and an alcohol. You ahve to refulx the ester with a dilute acid e.g HCL or sulphuric.
Base- refulx the ester with a dilute alkali e.g sodium hydroxide. You get a carboxylate ion and an alcohol.
How are polyesters formed?
Dicarboxylic acids and diols recat together to form long ester chains through condensation polymerisation.
- strong, flexible and abrasion resistant.
e.g Terylene is used in clothes to keep them crease free and make them last longer.
What is the funtional group of Acyl chlorides?
COCL
CnH(2n-1)OCL
How can acyl chlorides easily lose their chlorine?
React with water - a vigorous reacion producing a carboxylic.
React with alchohols - vigorous reaction producing an ester
React with concentrated ammonia - a violent reaction at room temp producing an amide
React with amines- A violent reaction producing an N-substituted amide.
each time CL is substitued by an oxygen or nitrogen group and hydrogen chloride fumes are given off.
Between carboxylic and acyl chloride, which reacts more vigorously with water?
carboxylic acid
