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Chapter 22 Study GuideAcyl groups (22.1)

Symmetrical anhydride: has 2 identical alkyl groups bonded to C atom

Mixed anhydride: has 2 different alkyl groups (i.e. acyl phosphate)

Know gamma-lactone and beta-lactam

Structure and function of carbonyls (22.2)

2 most important features: Carbonyl C is sp2 trigonal planar Carbonyl C is E+

Nitriles (CN): Sp hybridized, linear geometry Triple bonds have 1 sigma and 2 pi bonds Its C is E+

Nomenclature (22.3): NOTE: KNOW THIS FOR YOUR ACS AS WELL

For acid chlorides and acyl phosphates:

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Acyclic compounds:o For acid chlorides: change “-ic” “-yl chloride”o For acyl phosphates: change “-ic” “-yl phosphate”

Cyclic compounds o For acid chlorides: change “-carboxylic acid” “-carbonyl chlorides”o For acyl phosphates: change “-carboxylic acid” “-carbonyl phosphates”

For anhydrides: Symmetrical: change “-acid” “anhydride” Mixed: alphabetize acids and change “-acid” “anhydride”

In picture below: Symmetrical anhydride shown on left, and mixed anhydride shown on right:

For esters and thioesters: Esters: end in “-ate” Thioesters:

Cyclic: change “-xylic acid” “thioate” Acyclic: change “-oic acid” “ethioate” S precedes name of alkyl R group attached to the sulfur

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Name for (a): Derived from acetic acid It’s an ester so it should end in “-ate” Name R group = ethyl Answer = ethyl acetate

Name for (b): Parent: cyclohexanecarboxylic acid derivitive, but since it’s an ester, change “xylic acid”

“-ate” Name R group = tert-butyl Answer = tert-butyl cyclohexanecarboxylate

Name for (a): It’s an acyclic thioester, so change “-oic acid” “ethioate” Carbon chain of 4, so butane Attached R group is methyl

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Recall: S precedes name of alkyl R group attached to the sulfur Answer: S-methyl butanethioate

Name for (b): It’s a cyclic thioester, so change “xylic acid” “-thioate” Ring is a cyclopentane Attached R group is an isopropyl Answer: S-isopropyl cyclopentanecarbothioate

Primary amides: Change “-ic”, “-oic acid”, and “-ylic acid” “amide” “N” precedes the alkyl groups

o Add one N for each alkyl group attached to the nitrogen

Secondary and tertiary amides

Recall: N precedes name of alkyl R group attached to the sulfur There is one N per alkyl group

Nitriles The C in CN is carbon #1 and is counted in the chain

o i.e. if you have CN3CN2CN, your parent chain is 3 (not 2) carbons (we count the C in the CN)

o add “nitrile” to the end of the name

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o carbonyls still take priority over CN (i.e. ketone vs CN: the ketone will have carbon #1)

BP, MP, solubility, intramolecular forces of carbonyls and nitriles (22.3)

Have dipole-dipole interactions

Primary and secondary amides can H bond what does this mean for their melting and boiling points? Has higher bp than other

carboxylic acid derivatives

soluble in organic solvents<5C = soluble in H2O>5C = insoluble in H2O

Spectroscopy

IR: carboxylic acid derivatives:

o strong C=O absorption between 1600-1850 cm-

primary and secondary amides: o 1-2 N-H stretching peaks at 3200-3400 cm-

o N-H bending absorption at 1640 cm-

Phosphates:o Strong P=O absorption 1100-1200 cm-

Nitriles:o CN at 2250 cm-

As the carbonyl pi bond becomes more delocalized, the C=O absorption generally shifts to lower frequency

i.e. acid chloride has higher absorbance than amides because acid chlorides are not resonance stabilized, so they are localized rather than delocalized. Amides are resonance stabilized, so they are delocalized.

As basicity of the carboxylic acid derivative increases, wavenumber decreases.

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The more conjugated the carbonyl, the lower the wavenumber For cyclic carboxylic acid derivatives, as ring size decreases, frequency increases

Acyl phosphate: 1700-1730 cm-

Thioester: 1690-1720 cm-

NMR for carboxylic acid derivatives: protons on alpha carbon absorb 2-2.5 ppm N-H protons of primary and secondary amides absorb 7.5-8.5 ppm Carbonyl carbon is highly deshielded. Gives a peak at 160-180 ppm The C on the CN gives peak at 115-120 ppm

Interesting esters and amides (22.6)

Vitamin C: water soluble vitamin with 5-membered lactone

Proteins: polymers of amino acids joined together by amide linkages

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Nucleophilic acyl substitution (22.7)

The characteristic reaction of carboxylic acid derivatives

2 step mechanism: Nu- attack and then loss of leaving group

Better leaving groups are more reactive to Nu acyl substitution

Section 22.8 (soon to come)

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