Goals of the Day… Briefly review naming (from the online lesson) Please turn in your worksheet) Look at the physical properties of carboxylic acids and esters. 

Write the name of the acid in your notebook…

Answer…7-fluoro octanoic acid… (remember that the acid carbon is always carbon #1, so the groups on the chain have to get the “corresponding number” …

Write the name of the ester below in your notebook… There is a hint on the next slide. 

Remember that the esters are named in 2 sections… First name the group on the oxygen. Then name the rest of the chain.

Remember that the esters are named in 2 sections… First name the group on the oxygen. Then name the rest of the chain.

Ethyl hexanoate First name the group on the oxygen: ethyl. Then name the rest of the chain, there are 6 carbons, so it is hex…anoate.

Physical Properties for… Carboxylic Acids M.P./ B.P. rankings Water Solubility Acidity Rankings are… Groups with hydrogen bonding Groups with dipoles Groups with van der Waals forces

Polarity of Carboxylic Acids are strongly polar. have two polar groups. hydroxyl (−OH) and carbonyl (C═O)

Boiling Points of Carboxylic Acids The boiling points (bp) of carboxylic acids are higher than those of alcohols, ketones, and aldehydes of similar mass. are high because they form dimers in which hydrogen bonds form between two polar carboxyl groups.

Comparison of Boiling Points

Melting Point/ Boiling Point Ranks Rank these in order of their melting point temperatures (high to low)… > > > > _____

Melting Point/ Boiling Point Ranks Rank these in order of their melting point temperatures (high to low)… a c e d b > > > > _____

Solubility in Water Carboxylic acids form hydrogen bonds with many water molecules. with 1 to 4 carbon atoms are very soluble in water. Water molecules

Boiling Points and Solubility Solubility in Water (continued on the following slide..> Boiling Points and Solubility

Boiling Points and Solubility

Water Solubility… Which would be soluble in water?

Water Solubility Answer… Just the alcohol (a) The ether (b) is basically not soluble (slightly soluble) C is an alkane D has too many carbons

Acidity of Carboxylic Acids are weak acids. ionize in water to produce carboxylate ions and hydronium ions.

Acid Dissociation Constants Carboxylic acids have small acid dissociation constants. exist mostly as molecules and a few ions in aqueous solutions.

Neutralization of Carboxylic Acids Carboxylic acid salts are a product of the neutralization of a carboxylic acid with a strong base. are used as preservatives and flavor enhancers.

Boiling Points of Esters The boiling points of esters are higher than for alkanes of similar mass. are lower than alcohols and carboxylic acids of similar mass because esters cannot form hydrogen bonds with each other.

Melting Point/ Boiling Point Ranks Rank these in order of their melting point temperatures (high to low)… > > > > _____

Melting Point/ Boiling Point Ranks Rank these in order of their melting point temperatures (high to low)… c e b a d > > > > _____

Solubility in Water Esters are soluble in water when they have 1–5 carbon atoms. form hydrogen bonds from the partial negatively charged carbonyl oxygen to the partial positively charged hydrogen atoms in water. decrease their solubility in water with an increase in the number of carbon atoms.

Which are soluble in water?

Which are soluble in water? All but the last one, propane, are soluble in water! 

Reactions… Some you already know (so just review) Removing a proton (using a base) Forming an ester!  (oh, so sweet! ). 

Reactions that you know to make carboxylic acids…. Oxidation of primary alcohols or aldehydes Reagents can be H2CrO4, CrO3, [O], PCC, Benedicts, etc. Primary alcohols & aldehydes can be oxidized to carboxylic acids

Removing a hydrogen! (remember, they are acids!) 

The main Carboxylic Acid Reaction (need to be acid or base catalyzed)… Esterification… Important in fats Note 1: this is why esters are named the way they are…because they come from Carboxylic acids!  Note 2: This is an equilibrium reaction – this means it can also go “backwards.”

Esterificaton & Hydrolysis

Try to draw the following product in your notebook…

Note: the “group” of the alcohol is the “group” on the oxygen of the ester! 

Try to draw the following product in your notebook…

Remember, redraw the “acid” side, then add the “R” group of the alcohol to the oxygen of the ester… 

Try to draw the following product in your notebook…(there is a hint on the next slide)

Remember, you’re adding water to the ester to “break” it back into the acid and alcohol…

The acid breaks apart into the acid and alcohol.

Try to draw the following product in your notebook…(no color coordination this time, though)! 

There are 5 carbons in the acid and 2 in the alcohol

Base Hydrolysis (Saponification) Base hydrolysis (also called saponification) is the reaction of an ester with a strong base. produces the salt of the carboxylic acid and an alcohol.

“Soaps” The base hydrolysis of long-chain fatty acids produces acid salts called “soaps.”

Cleaning Action of Soap A soap contains a nonpolar end that dissolves in nonpolar fats and oils and a polar end that dissolves in water. forms groups of soap molecules called micelles that dissolve in water and are washed away. Micelles can take various forms, but this is pretty common…

“Trapping” Action of Soap Oil and grease are “trapped” inside the hydrophobic part of the micelle…

Soaps vs. Detergents Soaps contain a carboxylic acid Detergents contain a sulfur Sulfur doesn’t form bonds with the Ca+2 ions in water, so more is Available to “encase” the dirt on clothing…

Learning Check Give the following product…

Learning Check Remember that the water breaks the ester apart into the acid & alcohol…

Learning Check Give the following product…

Learning Check This is basically the same thing, but the acid is a salt since it is in a basic solution…

Comparing the acid and base products…