Nucleophilic Acyl Substitution- Reactivity of Carboxylic Acid Derivatives
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| Define Acyl Goup | Z--COR: includes carboxilic acids, acid chlorides, anhydrides, esters, and amides.
Z: OH, Cl, OCOR(anhydride), OR',NR'2
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| Define Lactones, y-lactone | Cyclic esters.
An ester in a five-membered ring.
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| Define Lactams | Cyclic amides.
An amide in a four-membered ring.
An amide in a five-membered ring.
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| Why can't aldehydes and ketones undergo nucleophilic acyl substitution? | Because aldehydes and ketones have no leaving group on the carbonyl carbon and cannot undergo nucleophilic substitutiion.
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| Why can Nitriles undergo nucleophilic substitution? | Nitriles are compounds that contain a cyano (C=-N) group bonded to an alkyl group.
Both RCN & ZCOR have one Catom with 3bonds to e-negative atoms.
CN sphybridized, 180, 1sigma, 2pi, e-philic carbon.
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| How do you determine the basicity of the leaving group? | You can compare pKa values of the conjugate acids HZ to determine the relative basicity of the LG Z.
(WB|SA) Cl-, RCOO-, -OH = -OR', -NR2 (SB|WA|More Stable)
The stonger the base, the stable the RCOZ, added resonace stabilization. WB=more reactive.
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| Naming an Acid Chloride—RCOCl | [1] For acyclic acid chlorides: Change the suffi x -ic acid of the parent carboxylic acid to the suffi x -yl chloride
[2] When the –COCl group is bonded to a ring: Change the suffi x -carboxylic acid to -carbonylchlorid
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| Common parent carboxylic acids | - Formic acid
- Acetic acid
- Benzoic acid
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| Naming an Anhydride | [1] Sym'cal anhydrides: change the acid ending of the parent carbox.acid to 'anhydride'.
[2] Mixed anhydrides, derived from two diff. carbox. acids: alphabetize the names for both acids and replace 'acid' by the word anhydride
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| Naming an Ester—RCOOR' | [1] Name the R' group bonded to the oxygen atom as an alkyl group -yl.
[2] Name the acyl group (RCO-): change the -ic acid ending of the parent carboxylic acid to the suffi x -ate.
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| Naming an Amide - Primary | [1] All 1° amides are named by replacing the -ic acid, -oic acid, or -ylic acid ending with the suffix -amide.
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| Naming an Amide - Secondary & Tertiary | [1] Name the alkyl group(s) bonded to N atom of the amide: Use the prefix “N-” preceding the name of each alkyl group.
[2] Name the acyl group (RCO-) with the suffi x -amide:Change the -ic acid/-oic acid of parent carboxylic acid to the suffi x-amide.
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| Naming a Nitrile | [1] Find the longest chain containing CN: + 'nitrile' to parent alkane.
[2] Number chain to put CN at C1, omit number.
[3] Common names: names of the carboxAs w/same # of Catms: replace -ic acid ending of CA w/ x-onitrile. CN substituent: "cyano"
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| Physical Properties of carbonyl compounds | ALL: LDF, DIP-DIP
Primary&Secondary amides: HBONDING
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| Why do carbonyl acid derivatives undergo nucleophilic acyl substitution rather than addition like aldehyde and ketones? | Just like Aldehydes and Ketones, carbonyl acid derivatives react with nucleophiles because they have an unhindered electrophilic carbonyl carbon. However, because they do have a leaving group Z on the carbonyl carbon, they undergo substitution.
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| Common nucleophiles: | -OH, H2O, ROH, RCOO-,NH3,RNH2,R2NH
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| Steps of predicting/drawing a nucleophilic acyl substitution product: | [1] Identify the sp2 hybridized carbon with the leaving group.
[2] Identify the nucleophile.
[3] Substitute the nucleophile for the leaving group.
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| Best Leaving Group= Weakest Base(SA) Order derivatives in increacing reactivity. | (Worst LG) -NH2, -OH = -OR', RCOO- , Cl -(best LG)
To form a substitution product, Z must be a better LG than NU.
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| What is required in nucleophilic substitution rxn with neutral nucleophiles (H2O, R'OH, NH3, and so forth)? | It equires an additional step for proton transfer.
[1] Nucleophilic addition at c=o, tetrahedral intermediate.
[2] Removal of a proton*
[3] Elimination of the leaving group
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| Anhydrides can't be used to make acid chlorides. Explain why. | RCOO– is a stronger base and therefore a poorer leaving group than Cl–. NS occurs only when the LG is a weaker base and therefore a better leaving group than the attacking nucleophile.
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