Organic chemistry chapter 20

Phthalic Acid=?

2 carboxyl groups on one benzene ring
What is the hybridization of the C’s and O’s in Carboxyl groups?

sp2 for both, because ressonance causes the O that would appear to be sp3 to form a double bond meaning that sp2 takes presidence.

boiling point relative to similar alcohols?

much higher due to dimer formation
Which acids are solid at room temperature?

Aliphatic acids of 8 carbons or more

What do double bonds do to the melting point of acids?

lower them

Explain the solubility of Carboxilic acids
Solubility in water decreases with chain length, up to 4 carbons in the acid is still soluble in water.  They are more soluble in alcohol, and more soluble in non-polar solvents that break up the dimer.

How do substituents affect acidity?

The more subsituents the more acidic the chain.  On a benzene: Activating in para<none<Deactivating in meta<deactivating in para<deactivating in ortho.

How does one convert the carboxylic acid to a salt?

How does one remake the acid from the salt?

Add sodium hydroxide to make it a salt, and a strong acid like HCl will return it to an acid.
What are some of the properties of acidic salts?
Solid with no real smell, and soluble in water if made with Na, K, Li, or NH4.
Formation of salt from an acid combined with NaHCO3 releases what?
What are the products formed from hydrolysis of a fat?
A glycerol and fatty acid salts

What are some identifying characteristics of a Carboxylic acid under UV Spectroscopy?

Saturated carboxylic acids have a weak absorbtion around 200-215 nm.  if C=C isconjugated with C=O, the molar absorptivity is 10,000 at 200nm.  An additional conjugated double bond increases the absorption to a wavelength of 250nm.
Why is the maximum value in Mass spectroscopy almost never observed?
because the molecule rearranges quickly
What are the main ways to synthesize carboxylic acids? (4)

1. Oxidation of primary alcohols and aldehydes using chromic acid or KMnO4 (makes an aldehyde first, and then forms a carboxylic acid).

2. an alkene with KMnO4 at high temperatures cleaves the double bond, forming a carboxylic acid if one C has an H on it.

3. Cleavage of an alkyne with ozone or hot permanganate.

4. Alkyl benzenes oxidized to Benzoic acid by Hot KMnO4 or hot chromic acid

Grignard reagent + CO2=?

Carboxylate salt (addition of a strong acid to form carboxylic acid)

How does one form a carboxylic acid from a nitrile?

by basic or acidic Hydrolysis
What is an anhydride?
A compound where there is an oxygen between 2 carbonyl groups.


ester+H20 (fischer esterification)
How is fischer esterification catalyzed?
in acidic media
What is a potentially unwanted quality of Fishcher esterification? How is it avoided?

All the steps are reversible, meaning it reaches an equillibrium.  It can be avoided by removing the water as it forms.

Explain the mechanism for fischer esterification?

1. Protonation of carbonyl and attack of an alcohol on the carbon (another alcohol takes the extra H)

2. Protonation of OH and loss of water, yielding the ester.

What is Diazomethane?
How does Diazomethane react with Carboxylic acids?
it produces methyl esters quantitative conversion, meaning no equilibrium. (gives off nitrogen gas)

How does an amine (base) react with carboxyilc acid?

It removes a proton to form a salt, and heating the salt above 100 C drives off steam and forms an amide.

Acid+LiAlH4 (followed by H20)=?

primary alcohol

What must be done to an acid in order to create an aldehyde? What happens otherwise?
The acid must be made more reactive (Ex, change it to an acid chloride) and be reduced with a weaker reducing agent (ex. LiAl[OC(CH3)3]3H) to yield an aldehyde.  Otherwise the reaction keeps going beyond an aldehyde
How do you form a Ketone from acids?
By reacting 2 equivalents of an organolithium reagent with the acid.
How does one synthesis and acid chloride?
by using thionyl chloride(SOCl2) or oxalyl chloride (C2O2Cl2)
Acid Chlorides + Alcohol=?
How does one form an amide from acid chlorides?
By addition of ammonia (a base can be added to remove the HCl byproduct)
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