The families of carboxylic acid derivatives are the esters, acid anhydrides, amides, and acid halide

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• Carboxylic acids contain a carbonyl group, CO,
  with an attached OH group. The entire
  functional group is called a carboxyl group and
  is often abbreviated COOH or CO2H.

• The families of carboxylic acid derivatives are
  the esters, acid anhydrides, amides, and acid
  halides

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• Constitutional isomers for carboxylic acids and
  their derivatives can be based on different
  carbon skeletons, or on different placements of
  the carboxyl group.
• The orbital hybridization of the carbonyl carbon
  and oxygen atoms is sp2 and the bond angles about
  the carbonyl group are 120.
• The atoms connected to the carbonyl group (C,N,O)
  are all sp3 hybridized with tetrahedral (109.5)
  bond angles.
• The oxidation state of carbon in a carboxylic
  acid is the highest of the organic compounds of
  carbon

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• Many carboxylic acids are referred to by their
  common names..

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• Carboxylic acids have higher secondary forces
  than alcohols, aldehydes, or ketones, and
  consequently have higher boiling and melting
  points.

• Both the carbonyl group and the hydroxyl group in
  a carboxylic acid are polar and capable of
  hydrogen bonding.

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• Both the carbonyl group and the hydroxyl group in
  a carboxylic acid are polar and capable of
  hydrogen bonding.

• The presence of these two groups allows
  carboxylic acids to form hydrogen bonded dimers
  under most conditions

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• The presence of these two groups allows
  carboxylic acids to form hydrogen bonded dimers
  under most conditions

• Carboxylic acids show slightly higher solubility
  in water than do alcohol because they can form
  three hydrogen bond interactions with water.
• The solubility of carboxylic acids decreases more
  slowly than that of alcohols as the number of
  carbons increases.
• C6 or higher carboxylic acids are insoluble.

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• Carboxylic acids are weak acids that ionized to
  form carboxylate ion and hydronium ion in water

• Ionization is less than 1-2, so the equilibrium
  lies far to the left.

• Carboxylic acids are weaker acids than the strong
  acids (HCl, H2SO4, HNO3, and HClO4), but stronger
  acids than phenols, and much stronger than
  alcohols.

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• Sodium hydroxide and sodium bicarbonate both
  react with carboxylic acids to form a carboxylate
  salt

• The sodium salt of butanoic acid would be called
  sodium butanoate.

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• Carboxylate salts are ionic and possess much
  higher boiling and melting points than those of
  the corresponding carboxylic acids (ionic forces
  are much stronger than secondary forces).
• All carboxylate salts are solids at room
  temperature.
• Sodium formate MP 253C solid at room
  temperature
• Formic acid MP 8C liquid at room temperature
• Carboxylate salts are much more soluble than
  their corresponding carboxylic acids.
• Sodium stearate (18 carbons) is water soluble.
• Stearic acid (18 carbons) is insoluble.

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• Soaps are sodium or potassium salts of long-chain
  (12 to 20 carbons) carboxylic acids (fatty
  acids) obtained from animal fats and plant oils.
• The fatty acid carboxylate salts are obtained
  from fats or oils by a process called
  saponification.
• An example of a soap is the sodium carboxylate
  salt of stearic acid, CH3(CH2)16COO-Na.

• Dirt adheres to surfaces rather than dissolving
  in water because it is hydrophobic or physically
  combined with a hydrophobic substance such as
  body oils, cooking fats, or greases.
• Soaps solubilize greasy dirt because they are
  amphipathicthat is, they contain both
  water-loving (hydrophilic) and water-hating
  (hydrophobic) parts.

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• The hydrophobic tail of a soap molecule has an
  affinity for the greasy dirt the hydrophilic
  head, for water

• The soap molecules, helped by mechanical
  agitation, break up the greasy dirt into smaller
  fragments and surround them, presenting a
  hydrophilic surface to the surrounding water.

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• The requirements for a good soap are an ionic
  group as the hydrophilic head and a long
  hydrocarbon group as the hydrophobic tail.
• Stearic acid, CH3(CH2)16COOH, does not function
  as a soap, because it does not possess an ionic
  head group. Its carboxylate salt is a good soap,
  however CH3(CH16)2COO-Na
• But, sodium butyrate, CH3(CH2)2COO-Na, does not
  function as a soap because its hydrocarbon tail
  is not long enough (not sufficiently
  hydrophobic).
• Soaps react with magnesium and calcium ions in
  hard water to precipitate soap as soap scum
• 2 CH3(CH16)2COO- (aq) Ca2 (aq) ?
  (CH3(CH16)2COO)2Ca (s)
• Water softeners replace hard calcium and
  magnesium ions in water with Na

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• Aliphatic carboxylic acids are the end products
  of the selective oxidation of alcohols and
  aldehydes

• Benzoic acid is the simplest aromatic carboxylic
  acid. It can be prepared by selective oxidation
  of alkyl benzenes

• All four types of carboxylic acid derivatives can
  be synthesized from carboxylic acids and
  hydrolyzed back to them.

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• When an acid is heated with an alcohol (R
  aliphatic) or a phenol (R aromatic) in the
  presence of a strong acid catalyst, an ester is
  formed.
• This process is called esterification.

• This reaction is driven to product by heating to
  the boiling point of water so that it is removed
  from the reaction mixture.

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• Esters can also be formed from the reaction of an
  alcohol (or phenol) with a carboxylic acid
  anhydride or halide, rather than a carboxylic
  acid.
• Aspirin (acetylsalicylic acid) is an ester
  derived from p-hydroxybenzoic acid (salicylic
  acid) and acetic acid.

• Esters of carboxylic acids have pleasant odors
  and flavors
• Pineapple ethyl butanoate Raspberry isobutyl
  methanoate Banana 3-methyl-butyl ethanoate

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Example
Ethyl benzoate
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• Esters have much lower boiling and melting points
  than those of carboxylic acids. Ester molecules
  cannot hydrogen bond to each other.
• Propanoic acid 141C
• Methyl acetate 57C
• Esters are less soluble in water than are
  carboxylic acids because esters cannot form as
  many hydrogen bonds to water molecules as can
  carboxylic acids.
• The secondary forces in esters are weaker than
  those in aldehydes and ketones, and thus esters
  have lower melting and boiling points.
• Methyl acetate 57C
• Butanal 76C
• Esters have about the same water solubilities as
  aldehydes and ketones because all three hydrogen
  bond to water equally well.

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• When the reactants in an esterification reaction
  are bifunctional, polymerization can occur. The
  reactants behave as monomers which link together
  in large numbers (gt50) to produce polymers.

• Esterfication of a dicarboxylic acid and a diol
  produces a polyester.

• The polymer is usually drawn in abbreviated form
  with brackets surrounding the repeat unit of
  monomers

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• This type of polymerization is called
  condensation polymerization. In condensation
  polymerization a small molecule (in this case,
  water) is a product of the polymerization
  process.
• In a second type of polymerization called
  addition polymerization, no small byproducts are
  formed. This type of polymerization takes place
  with alkenes.

• The following polymerization produces
  poly(ethyleneterephthalate) or PET. This is also
  known as Dacron, Mylar, or polyester.

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• The hydrolysis of an ester to the corresponding
  carboxylic acid and alcohol (or phenol) occurs
  under either acidic or basic conditions.
• Acidic hydrolysis requires the presence of a
  strong acid

• Acidic hydrolysis of an ester is the reverse of
  the acid catalyzed formation of an ester. Both
  are equilibrium reactions.
• The equilibrium can be shifted to favor
  hydrolysis by carrying out the reaction with a
  large excess of water.
• Basic hydrolysis requires a strong base such as
  NaOH or KOH

• This reaction is also called saponification, and
  is used to manufacture soaps from certain animal
  fats and vegetable oils.

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• Acidic and basic hydrolysis differ in two
  important ways

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• The term anhydride indicates a compound that is
  formed by dehydration. In the carboxylic acid
  anhydrides, two carboxylic acids are joined
  together by the removal of a molecule of water
  between them.
• Acid anhydrides and halides are highly reactive
  with water and are not found in biological
  systems.

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• Carboxylic acid anhydrides are named by changing
  the word acid to anhydride in the name of the
  carboxylic acid.
• Acid halides (acyl halides) are named by changing
  the name of the carboxylic acid from ic acid to
  yl halide.

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• Acid anhydrides react with alcohols (or phenols)
  to form esters

• Ester synthesis from anhydrides or acid halides
  is more efficient than from the carboxylic acid
  itself. This is how aspirin is made.

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• Acids other than carboxylic acids can form
  anhydrides. Phosphoric acid can form both
  diphosphoric acid and triphosphoric acid

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Many phosphate esters are biologically
important ATP, NADH and NAD, phospholipids, DNA
and RNA (nucleic acids), and phosphate esters of
carbohydrates.