Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
20 Cards in this Set
- Front
- Back
|
Carboxylic Acids: R-COOH -most reactive we will find on test day |
COOH: carbon w/ C=O bond and an -OH Can act as nucleophiles, electrophiles, acids.. *integral to many biological processes **most importantly: amino acids!! Acids: give away protons - remaining negative charge easily stabilized among oxygens COOH some of most acidic functional groups pKA from 3 to 6 compare with alcohols---pKa around 17 Always terminal carbons |
|
|
COOH Properties
|
one of most oxidized functional grops - end in oic acid Polar: can H bond ex: formic acid (1C) methanoic acid acetic acid- ethanoic acic propionoic acid - once COOH loses its H--> COO- called -oic acid --> -oate x2 COOH on a molecule: -dioic acid |
|
|
Physical Properties of COOH
|
-many similar to aldehydes and ketones (both have carbonyl carbons) -Strong intermolecular interactions - b/c OH and C=O -participates in hydrogen bonding
-can form dimers: two molecules connected via H bonds **remember: more H bonding= inc^ BP, MP ** higher than alcohols and increase w/ weight |
|
|
COOH Acidity
|
-OH Hydrogen: very acidic - if removed, leaves (-) charge - resonance stablizied w/ oxygens(EN) - very stable carboxylate anions a stable conjugate base= stronger acid * easily dissociates (high Ka) * COOH pKas: Lower is Stronger acid ex: acetic acid: 4.8 propionic acid 4.9 (more weight) |
|
|
Nearby Substituent affects on COOH acidity
|
*remember strong acids, HCl pKa is -8 compared to COOH @ ~4.8 Substitutents can influence anion stability ex: NO2-, halides withdraw electrons increase acidity *closer to COOH, stronger affect dicarboxylic acids stronger than single.. Electron donating Groups: reduce acidity - ex: NH2+, OCH3 - they destabilize the "stable" anion |
|
|
Beta- Carboxylic Acids |
HOOC-CH2-COOH dicarboxylic acid beta alpha beta Alpha-adjacent beta carbons are two carbons away
-alpha carbons are very acidic located between the two COOH Groups alpha C pKa~ 9-14 Carbanion very stable w/o H |
|
|
COOH Reactions
|
COOH properties make them highly reactive - can make COOH via oxidation of aldehyde - CrO3, potassium permanganate (KMnO4) **secondary & tertiary will not make COOH
*Grignard Reagents/ hydrolysis of Nitriles will yield carboxylic acids |
|
|
Nucleophilic Acyl Substitutions
|
COOH participate often in nucleophilic acyl substitution reactions - similar to nucleophilic addition to aldehydes and ketones in Carboyxylic acids.. a nucleophile will attack the carbonyl carbon, opening up the COOH - breaking C=O pi bond, pi electrons to Oxy Carbonyl can reform (in tetrahedral intermediate) and kick off the leaving group **key point: the nucleophile (stronger base) kicks off the weaker base (the -OH in COOH) - leaving groups off, favored in acid/basic solutions |
|
|
Acyl Derivatives
|
COOH Derived Carbonyl group - includes: * carboxylic acids, amides, esters, anhydrides, and others |
|
|
Amides
|
COOH can convert to amides - incoming nucleophile would be :NH3 * can be in acidic or basic solution *-OH of COOH and H of NH3 form H2O Amide Carbonyl bond to NH-R group -Forms amide via Nucleophilic acyl substitution |
|
|
Cyclic Amides -Lactams |
Lactams: amides that are cyclic - end in lactam, or name C that was cyclized still have the amide bond C=O to an NH |
|
|
Ester Formation
|
Esters: Hybrids between COOH and an ether (ROR') esterification: condensation rxn - water as side product 1. protonate the COOH C=O --> C-OH w/ acidic solution -in acidic conditions - forms stronger electrophile between the OH groups 2. Nucleophile attacks the more (+) carbon - carbonyl opened, reforms-kicks off :OH -
-esterification is really fast w/ a primary alcohol Cyclic Esters: Lactones: COOH derivates C=O part of cyclic group that has ROR' ester group |
|
|
Anhydride formation -x2 COOH |
Condensation rxn - two COOH condensate to make anhydride -ends in anhydride, cyclic or linear Synthesis: via condensation COOH and COOH combine w/ ester bond -makes H2O and anhydride |
|
|
COOH Reduction
|
COOH----> primary Alcohols -via strong reducing agent: LiAlH4 - multistep- OH kicked off w/ nucleophilic attack - aldehyde intermediate w/ reform of carbonyl - C=O is protonated to form a primary alcohol **NaBH4 too gentle for COOH, will not work |
|
|
COOH Decarboxylation
|
Decarboxy: remove C as CO2 -common way to remove carbon from parent chain Ex: decarboxylation of 1,3 dicarboxyethanoic acid - cut after first carbon - products are CO2 (lost hydrogen to fill gap) and an enol(unstable) <--> Keto(stable) left |
|
|
Saponification
|
long chain COOH w/ KOH/ NaOH - Acid + Base --> form salt salt/ soap can solvate nonpolar organic molecules in aqueous solution Soap: contains nonpolar tail and a polar COOH head - in aqueous (polar) solution: soap forms micelles *polar heads towards polar solution, nonpolar tails on inside - grease(nonpolar) dissolve in hydrocarbon interior and eventualyl micelle dissolves in water from polarity |
|
|
Esters
|
COOH + OH - oate esterifying group: bound to new O Fischer esterification: -under acidic conditions - mixture of COOH and alcohols condense into esters -same mechanism: 1. COOH C=O protonated to C-OH 2. Nucleophile attacks (+) carbon - forms ester bond, breaks pi bonds (to O) - original OH of COOH steals a hydrogen of esterifying group- and forms H2O -essentially the leaving group 2. Carbonyl reforms, stabilizes w/ new ester group + H2O\ *Esters important in Triacylglycerides - Glycerol+ COOH esters to fatty tails - saponification: hydrolyzed fats in basic cond. to produce soaps ( COOH polar head, nonpolar tail) |
|
|
COOH Derivatives Reactivity Principles
|
Anhydrides: most reactive - has 3 e- withdrawing groups Esters and COOH are middle reactive Amides- Least reactive Steric Hindrance: **pay attention to # substituent groups.. a rxn will not proceed if too many.. prime ex: Sn2 (bimolecular) rxn
Sn2: rate determined by two molecules in reactants - nucleophile and leaving group - happens in one step Tertiary carbons are okay in Sn1: two step rxn - Sn2 will not happen` |
|
|
Anhydride Cleavage --all via acyl nucleophilic substitution - NH3 can react with x2 COOh - forms COOH and amide - OH can react with x2 COOH - forms ester and COOH -Exposure to H2O - x2 COOH revert back to two sep. COOH |
*can be nucleophilic substitution as well as cleavage reaction :NH3 ammonia: nucleophile attacks a carbonyl of a anhydride 1. ester oxygen bonds one of NH3's H 2. ester bond breaks on nucleophilic attack side - side where NH3 attacked carbonyl carbon -forces pi bonds to move to oxygen - those Pi bonds reform, kicking off the oxygen- bound to other carbonyl Products: amide( C=O bonded to N) -carboxylic acid: COOH |
|
|
Amide Hydrolysis
|
Amides : C=O bound to an NHR group - React amide with water, to reform COOH and NH3 **still nucleophilic acyl substitution |
