Notes for 4/4

Esters

  • Esters are chemical compounds formed by reacting carboxylic acids and alcohols, effectively condensing an organic acid with an alcohol.

    • General formula: R−COOH+R′OH⇌R−COOR′+H2OR-COOH + R'OH \rightleftharpoons R-COOR' + H_2O where:

      • R is from the carboxylic acid.

      • R' is from the alcohol.

  • Most naturally occurring fats and oils are fatty acid esters of glycerol.

  • Low molecular weight esters are used as fragrances and found in essential oils and pheromones.

  • Phosphoesters form the backbone of DNA molecules.

  • Nitrate esters (e.g., nitroglycerin) are known for their explosive properties.

  • Polyesters are important plastics with monomers linked by ester moieties.

  • Ester names are derived from the parent alcohol and carboxylic acid (e.g., butyl acetate from butanol and acetic acid, C6H12O2).

  • Esters are responsible for the aroma of many fruits, including apples, pears, bananas, pineapples, and strawberries.

  • Several billion kilograms of polyesters are produced industrially annually.

  • Esterification is the general name for a chemical reaction between two reactants (typically an alcohol and an acid) to form an ester.

Esterification and Hydrolysis

  • Esterification:

    R−COOH+R′OH⇌R−COOR′+H2OR-COOH + R'OH \rightleftharpoons R-COOR' + H_2O

    • Carboxylic acid + Alcohol yields Ester + Water

  • Esterification is a reversible reaction.

  • Hydrolysis: Esters undergo hydrolysis under acid and basic conditions.

    • Acid conditions: The reaction is the reverse of esterification.

    • Basic conditions: Hydroxide acts as a nucleophile, and an alkoxide is the leaving group. This reaction, saponification, is the basis of soap making. R−COOR′+NaOH→R−COO−Na++R′OHR-COOR' + NaOH \rightarrow R-COO^-Na^+ + R'OH

      • Carboxylate ester + Sodium hydroxide yields Sodium carboxylate + Alcohol

Common Esters and Their IUPAC Names

  • Methyl formate: HCOOCH3HCOOCH_3 (methyl methanoate)

  • Methyl acetate: CH3COOCH3 (methyl ethanoate)

  • Ethyl acetate: CH3COOCH2CH_3 (ethyl ethanoate)

  • Ethyl propionate: CH3CH2COOCH2CH3 (ethyl propanoate)

  • Isopropyl butyrate: CH3CH2CH2COOCH(CH3)_2 (isopropyl butanoate)

  • Ethyl benzoate: C6H5COOCH2CH3

Occurrence and Use

  • Esters are common in organic chemistry and biological materials, often with a pleasant, fruity odor.

  • Extensively used in the fragrance and flavor industry.

  • Examples:

    • Methyl butanoate (apple):
      CH<em>3OH+C</em>3H<em>7COOH→C</em>3H<em>7COOCH</em>3+H2OCH<em>3OH + C</em>3H<em>7COOH \rightarrow C</em>3H<em>7COOCH</em>3 + H_2O
      Methanol + Butanoic acid yields Methyl butanoate + Water

    • Ethyl butanoate (pineapple):
      C<em>2H</em>5OH+C<em>3H</em>7COOH→C<em>3H</em>7COOC<em>2H</em>5+H2OC<em>2H</em>5OH + C<em>3H</em>7COOH \rightarrow C<em>3H</em>7COOC<em>2H</em>5 + H_2O
      Ethanol + Butanoic acid yields Ethyl butanoate + Water

    • Pentyl ethanoate (banana):
      C<em>5H</em>11OH+CH<em>3COOH→CH</em>3COOC<em>5H</em>11+H2OC<em>5H</em>{11}OH + CH<em>3COOH \rightarrow CH</em>3COOC<em>5H</em>{11} + H_2O
      Pentanol + Ethanoic acid yields Pentyl ethanoate + Water

    • Pentyl butanoate (apricot):
      C<em>5H</em>11OH+C<em>3H</em>7COOH→C<em>3H</em>7COOC<em>5H</em>11+H2OC<em>5H</em>{11}OH + C<em>3H</em>7COOH \rightarrow C<em>3H</em>7COOC<em>5H</em>{11} + H_2O
      Pentanol + Butanoic acid yields Pentyl butanoate + Water

    • Octyl butanoate (orange):
      C<em>8H</em>17OH+C<em>3H</em>7COOH→C<em>3H</em>7COOC<em>8H</em>17+H2OC<em>8H</em>{17}OH + C<em>3H</em>7COOH \rightarrow C<em>3H</em>7COOC<em>8H</em>{17} + H_2O
      Octanol + Butanoic acid yields Octyl butanoate + Water

Amines

  • Amines are organic compounds containing a basic nitrogen atom.

  • They are derivatives of ammonia, where one or more hydrogen atoms are replaced by substituents such as alkyl or aryl groups.

  • Important amines include amino acids, biogenic amines, trimethylamine, and aniline.

Classification of Amines

  • Primary (1°) amine: One hydrogen atom in ammonia is replaced by an alkyl group (R−NH2R-NH_2).

    • Examples: methylamine, ethanolamine (2-aminoethanol).

  • Secondary (2°) amine: Two alkyl substituents are bound to the nitrogen atom along with one hydrogen (R1-NH-R2).

    • Examples: dimethylamine and methylethanolamine.

  • Tertiary (3°) amine: All three hydrogen atoms are replaced by organic substituents (NR1R2R_3).

    • Example: trimethylamine.

  • Aromatic amines: The nitrogen atom is connected to an aromatic ring (e.g., aniline).

    • The aromatic ring decreases the alkalinity of the amine, depending on its substituents.

    • The amine group increases the reactivity of the aromatic ring due to an electron-donating effect.

Nomenclature

  • Amines are named with the prefix "amino-" or the suffix "-amine."

  • The prefix "N-" indicates substitution on the nitrogen atom.

  • Compounds with multiple amino groups are called diamines, triamines, tetraamines, etc.

  • Lower amines are named with the suffix amine (e.g. methylamine).

  • Higher amines use prefix amino as a functional group (e.g. 2-aminopentane).

Properties of Amines

  • Methylamine and ethylamine are gases under standard conditions, while corresponding alcohols are liquids.

  • Gaseous amines possess a characteristic ammonia smell; liquid amines have a distinctive "fishy" smell.

  • Low molecular weight amines are toxic and can be absorbed through the skin.

  • Many higher molecular weight amines are biologically active.

  • Alkaloids are amines isolated from plants, including poisons (nicotine) and drugs (morphine, cocaine).

Production of Amines

  • Industrially significant amines are prepared from ammonia by alkylation with alcohols:
    ROH + NH3 \rightarrow RNH2 + H_2O</p></li><li><p>Reductionofnitro−compounds:<br>CH<em>3CH</em>2CH<em>2NO</em>2→CH<em>3CH</em>2CH<em>2NH</em>2</p></li><li><p>Reduction of nitro-compounds:<br>CH<em>3CH</em>2CH<em>2NO</em>2 \rightarrow CH<em>3CH</em>2CH<em>2NH</em>2
    Nitropropane to Propylamine

  • Reduction of nitriles:
    CH3C≡N \rightarrow CH3CH2NH2<br>MethylnitriletoEthylamine</p></li></ul><h3id="3f4d714f−e9a0−4b02−bacd−0f267a56b3b0"data−toc−id="3f4d714f−e9a0−4b02−bacd−0f267a56b3b0"collapsed="false"seolevelmigrated="true">AminoAcids</h3><ul><li><p>Aminoacidsaremoleculescontaininganaminegroup,acarboxylicacidgroup,andaside−chain(Rgroup)thatvariesbetweendifferentaminoacids.</p></li><li><p>Keyelements:carbon,hydrogen,oxygen,andnitrogen.</p></li><li><p>Importantinbiochemistry,referringtoalpha−aminoacids.</p></li></ul><h4id="a72d5bd9−6713−4e54−99e9−8ed53618e26b"data−toc−id="a72d5bd9−6713−4e54−99e9−8ed53618e26b"collapsed="false"seolevelmigrated="true">Structure</h4><ul><li><p>Generalstructure:</p></li><li><p>Aminoacidsplaycentralrolesasbuildingblocksofproteinsandasintermediatesinmetabolism.</p></li><li><p>The20aminoacidsfoundwithinproteinsprovidechemicalversatility.</p></li><li><p>Thesequenceofaminoacidsinaproteinisdeterminedbythesequenceofbasesinthegenethatencodestheprotein.</p></li><li><p>Thechemicalpropertiesofaminoacidsdeterminethebiologicalactivityoftheprotein.</p></li><li><p>Proteinscatalyzereactionsinlivingcellsandcontrolcellularprocesses.</p></li><li><p>Aminoacidsequencescontaininformationforproteinfoldingintoathree−dimensionalstructureandthestabilityofthatstructure.</p></li><li><p>Proteinfoldingandstabilityisanactiveresearcharea.</p></li></ul><h4id="c322dce2−806e−4715−a833−196fde75f8ea"data−toc−id="c322dce2−806e−4715−a833−196fde75f8ea"collapsed="false"seolevelmigrated="true">EssentialvsNon−EssentialAminoAcids</h4><ul><li><p>Aminoacidsarethechemicalunitsor"buildingblocks"ofthebodythatmakeupproteins.</p></li><li><p>Proteinsareessentialformuscles,tendons,organs,glands,nails,andhair.</p></li><li><p>Theyarecriticalforgrowth,repair,andmaintenanceofcells.</p></li><li><p>Proteinsmakeupthegreatestportionofourbodyweightnexttowater.</p></li><li><p>Essentialaminoacidsarethosethatmustbeobtainedfromthediet.</p></li><li><p>Non−essentialaminoacidsarethosethatthebodycanmanufacturefromothersources.</p></li><li><p>Humanscanproduce10ofthe20aminoacids:</p><ul><li><p>alanine,asparagine,asparticacid,cysteine,glutamicacid,glutamine,glycine,proline,serine,andtyrosine.</p></li></ul></li><li><p>Plantsmustbeabletosynthesizeallaminoacids.</p></li></ul><h4id="952bcce2−1ae4−4aa6−bcea−d9d73e0dd440"data−toc−id="952bcce2−1ae4−4aa6−bcea−d9d73e0dd440"collapsed="false"seolevelmigrated="true">ExamplesofAminoAcids</h4><ul><li><p>Leucine</p></li><li><p>Valine</p></li><li><p>Glycine</p></li><li><p>Alanine</p></li><li><p>Methionine</p></li><li><p>Tyrosine</p></li></ul><h3id="156362d8−a2d5−43ee−bf78−a7bc0194d10e"data−toc−id="156362d8−a2d5−43ee−bf78−a7bc0194d10e"collapsed="false"seolevelmigrated="true">PeptidesandProteins</h3><ul><li><p>Peptidesareshortpolymersofaminoacidslinkedbypeptidebonds.</p></li><li><p>Theyhavethesamepeptidebondsasproteinsbutareshorter.</p></li><li><p>Dipeptidesconsistoftwoaminoacidsjoinedbyasinglepeptidebond.</p></li><li><p>Tripeptides,tetrapeptides,etc.,existwithincreasingnumbersofaminoacids.</p></li><li><p>Peptideshaveanaminoend(N−terminus)andacarboxylend(C−terminus),unlesstheyarecyclicpeptides.</p></li></ul><h4id="4924110f−cecf−44f1−bdd1−ba3890bb3e66"data−toc−id="4924110f−cecf−44f1−bdd1−ba3890bb3e66"collapsed="false"seolevelmigrated="true">PeptideBondFormation</h4><ul><li><p>Theamineandcarboxylicacidgroupsofaminoacidscanreacttoformamidebonds(peptidebonds).</p></li><li><p>Thepolymerizationofaminoacidscreatesproteins.</p></li><li><p>Thiscondensationreactionformsapeptidebondandreleasesamoleculeofwater.</p></li><li><p>Dipeptideformation:</p></li><li><p>Aminoacid(1)+Aminoacid(2)−>Dipeptide+Water</p></li><li><p>Apolypeptideisasinglelinearchainofaminoacidsbondedtogetherbypeptidebonds.</p></li><li><p>Proteinmoleculesconsistofoneormorepolypeptidesinabiologicallyfunctionalwayandsometimeshavenon−peptidegroupsattached.</p></li></ul><h4id="c759d496−6f3c−4e48−893a−cfe19366a16c"data−toc−id="c759d496−6f3c−4e48−893a−cfe19366a16c"collapsed="false"seolevelmigrated="true">ProteinStructureandFunction</h4><ul><li><p>Thehumanbodymakesatleast50,000differentproteinsorpossiblytwicethatmany.</p></li><li><p>Proteinsareessentialworkingpartsoflivingmatter.</p></li><li><p>Eachproteinhasaparticularshapeandfunctionthatareinextricablylinked.</p></li><li><p>Examples:</p><ul><li><p>Hemoglobin′sshapeenablesittocarryoxygen.</p></li><li><p>Collagen′sshapemakesitagoodconnectivetissue.</p></li><li><p>Insulinfitsinspaceslikeakey,enablingittoturnthingsonandoff.</p></li></ul></li><li><p>Proteinshavedifferentfunctions:</p><ul><li><p>Structure(ligaments,fingernails,hair).</p></li><li><p>Digestion(stomachenzymes).</p></li><li><p>Movement(muscles).</p></li><li><p>Vision(lensofoureyesispurecrystallineprotein).</p></li></ul></li></ul><h4id="129b6996−4e1a−42df−bc82−f2a2311cca93"data−toc−id="129b6996−4e1a−42df−bc82−f2a2311cca93"collapsed="false"seolevelmigrated="true">Denaturation</h4><ul><li><p>Denaturationisaprocessinwhichproteinsornucleicacidslosetheirtertiaryandsecondarystructure.</p></li><li><p>Causedbyexternalstressorcompoundssuchas:</p><ul><li><p>strongacidsorbases.</p></li><li><p>concentratedinorganicsalts.</p></li><li><p>organicsolvents(e.g.,alcoholorchloroform).</p></li><li><p>heat.</p></li></ul></li><li><p>Denaturationdisruptscellactivityandcancausecelldeath.</p></li><li><p>Denaturedproteinscanexhibitlossofsolubilityorcommunalaggregation.</p></li></ul><h3id="f648a1fb−bea7−4e60−8dd0−dfed1429f6d6"data−toc−id="f648a1fb−bea7−4e60−8dd0−dfed1429f6d6"collapsed="false"seolevelmigrated="true">MechanismofOrganicChemicalReactions</h3><ul><li><p>Areactionmechanismisthestep−by−stepsequenceofelementaryreactionsbywhichanoverallchemicalchangeoccurs.</p></li><li><p>Itdescribesindetailwhattakesplaceateachstageofanoverallchemicalreaction(transformation).</p></li><li><p>Itdescribeseachreactionintermediate,activatedcomplex,andtransitionstate.</p></li><li><p>Itshowswhichbondsarebroken(andinwhatorder)andwhichbondsareformed(andinwhatorder).</p></li><li><p>Acompletemechanismaccountsforallreactantsused,thefunctionofacatalyst,stereochemistry,allproductsformed,andtheamountofeach.</p></li><li><p>Italsodetailstherelativeratesofthesteps.</p></li><li><p>Reactionintermediatesarechemicalspecies,oftenunstableandshort−lived,thatarenotreactantsorproductsoftheoverallreactionbutaretemporaryproductsandreactantsinthemechanism′sreactionsteps.</p></li><li><p>Reactionintermediatesareoftenfreeradicalsorions.</p></li><li><p>Transitionstatesareunstableintermediatemolecularstatesinelementaryreactions.</p></li><li><p>Transitionstatesinvolveanunstablenumberofbondsand/orunstablegeometryatchemicalpotentialmaxima.</p></li></ul><p><em>SN2exampleshownintranscript</em></p><ul><li><p>Thereisnolimittothenumberofpossibleorganicreactionsandmechanisms.</p></li><li><p>However,certaingeneralpatternsareobservedtodescribemanycommonorusefulreactions.</p></li><li><p>Eachreactionhasastepwisereactionmechanismthatexplainshowithappens,althoughthisdetaileddescriptionofstepsisnotalwaysclearfromalistofreactantsalone.</p></li></ul><h4id="b52d9a07−3b8f−4270−b0a9−0e4567046326"data−toc−id="b52d9a07−3b8f−4270−b0a9−0e4567046326"collapsed="false"seolevelmigrated="true">BasicTypesofOrganicReactions</h4><ul><li><p>Organicreactionscanbeorganizedintoseveralbasictypes;somereactionsfitintomorethanonecategory.</p><ul><li><p>Substitution:Replacementofoneatomorgroupwithanother.</p></li><li><p>Addition:Combiningtworeactantstoformasingleproduct.</p></li><li><p>Elimination:Removingatomsorgroupsfromamoleculetoformamultiplebond.</p></li><li><p>Rearrangement:Changingtheconnectivityofatomsinamolecule.</p></li></ul></li></ul><h3id="a1cfea51−31c7−4d72−8a55−0a037c3a44f0"data−toc−id="a1cfea51−31c7−4d72−8a55−0a037c3a44f0"collapsed="false"seolevelmigrated="true">CarboxylicAcids</h3><ul><li><p>Carboxylicacidsareorganicacidscharacterizedbythepresenceofatleastonecarboxylgroup.</p></li><li><p>ThegeneralformulaofacarboxylicacidisR−COOH.</p></li><li><p>Acarboxylgroup(orcarboxy)isafunctionalgroupconsistingofacarbonyl(RR′C=O)andahydroxyl(R−O−H),whichhastheformula−C(=O)OH,usuallywrittenas−COOH.</p></li><li><p>CarboxylicacidsareBronsted−Lowryacids;theyareprotondonors.</p></li><li><p>Theyarethemostcommontypeoforganicacid.</p></li><li><p>Examples:</p><ul><li><p>Formicacid(H−COOH):Occursinants.</p></li><li><p>Aceticacid(<br>Methylnitrile to Ethylamine</p></li></ul><h3 id="3f4d714f-e9a0-4b02-bacd-0f267a56b3b0" data-toc-id="3f4d714f-e9a0-4b02-bacd-0f267a56b3b0" collapsed="false" seolevelmigrated="true">Amino Acids</h3><ul><li><p>Amino acids are molecules containing an amine group, a carboxylic acid group, and a side-chain (R group) that varies between different amino acids.</p></li><li><p>Key elements: carbon, hydrogen, oxygen, and nitrogen.</p></li><li><p>Important in biochemistry, referring to alpha-amino acids.</p></li></ul><h4 id="a72d5bd9-6713-4e54-99e9-8ed53618e26b" data-toc-id="a72d5bd9-6713-4e54-99e9-8ed53618e26b" collapsed="false" seolevelmigrated="true">Structure</h4><ul><li><p>General structure:</p></li><li><p>Amino acids play central roles as building blocks of proteins and as intermediates in metabolism.</p></li><li><p>The 20 amino acids found within proteins provide chemical versatility.</p></li><li><p>The sequence of amino acids in a protein is determined by the sequence of bases in the gene that encodes the protein.</p></li><li><p>The chemical properties of amino acids determine the biological activity of the protein.</p></li><li><p>Proteins catalyze reactions in living cells and control cellular processes.</p></li><li><p>Amino acid sequences contain information for protein folding into a three-dimensional structure and the stability of that structure.</p></li><li><p>Protein folding and stability is an active research area.</p></li></ul><h4 id="c322dce2-806e-4715-a833-196fde75f8ea" data-toc-id="c322dce2-806e-4715-a833-196fde75f8ea" collapsed="false" seolevelmigrated="true">Essential vs Non-Essential Amino Acids</h4><ul><li><p>Amino acids are the chemical units or "building blocks" of the body that make up proteins.</p></li><li><p>Proteins are essential for muscles, tendons, organs, glands, nails, and hair.</p></li><li><p>They are critical for growth, repair, and maintenance of cells.</p></li><li><p>Proteins make up the greatest portion of our body weight next to water.</p></li><li><p>Essential amino acids are those that must be obtained from the diet.</p></li><li><p>Non-essential amino acids are those that the body can manufacture from other sources.</p></li><li><p>Humans can produce 10 of the 20 amino acids:</p><ul><li><p>alanine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, proline, serine, and tyrosine.</p></li></ul></li><li><p>Plants must be able to synthesize all amino acids.</p></li></ul><h4 id="952bcce2-1ae4-4aa6-bcea-d9d73e0dd440" data-toc-id="952bcce2-1ae4-4aa6-bcea-d9d73e0dd440" collapsed="false" seolevelmigrated="true">Examples of Amino Acids</h4><ul><li><p>Leucine</p></li><li><p>Valine</p></li><li><p>Glycine</p></li><li><p>Alanine</p></li><li><p>Methionine</p></li><li><p>Tyrosine</p></li></ul><h3 id="156362d8-a2d5-43ee-bf78-a7bc0194d10e" data-toc-id="156362d8-a2d5-43ee-bf78-a7bc0194d10e" collapsed="false" seolevelmigrated="true">Peptides and Proteins</h3><ul><li><p>Peptides are short polymers of amino acids linked by peptide bonds.</p></li><li><p>They have the same peptide bonds as proteins but are shorter.</p></li><li><p>Dipeptides consist of two amino acids joined by a single peptide bond.</p></li><li><p>Tripeptides, tetrapeptides, etc., exist with increasing numbers of amino acids.</p></li><li><p>Peptides have an amino end (N-terminus) and a carboxyl end (C-terminus), unless they are cyclic peptides.</p></li></ul><h4 id="4924110f-cecf-44f1-bdd1-ba3890bb3e66" data-toc-id="4924110f-cecf-44f1-bdd1-ba3890bb3e66" collapsed="false" seolevelmigrated="true">Peptide Bond Formation</h4><ul><li><p>The amine and carboxylic acid groups of amino acids can react to form amide bonds (peptide bonds).</p></li><li><p>The polymerization of amino acids creates proteins.</p></li><li><p>This condensation reaction forms a peptide bond and releases a molecule of water.</p></li><li><p>Dipeptide formation:</p></li><li><p>Amino acid (1) + Amino acid (2) -> Dipeptide + Water</p></li><li><p>A polypeptide is a single linear chain of amino acids bonded together by peptide bonds.</p></li><li><p>Protein molecules consist of one or more polypeptides in a biologically functional way and sometimes have non-peptide groups attached.</p></li></ul><h4 id="c759d496-6f3c-4e48-893a-cfe19366a16c" data-toc-id="c759d496-6f3c-4e48-893a-cfe19366a16c" collapsed="false" seolevelmigrated="true">Protein Structure and Function</h4><ul><li><p>The human body makes at least 50,000 different proteins or possibly twice that many.</p></li><li><p>Proteins are essential working parts of living matter.</p></li><li><p>Each protein has a particular shape and function that are inextricably linked.</p></li><li><p>Examples:</p><ul><li><p>Hemoglobin's shape enables it to carry oxygen.</p></li><li><p>Collagen's shape makes it a good connective tissue.</p></li><li><p>Insulin fits in spaces like a key, enabling it to turn things on and off.</p></li></ul></li><li><p>Proteins have different functions:</p><ul><li><p>Structure (ligaments, fingernails, hair).</p></li><li><p>Digestion (stomach enzymes).</p></li><li><p>Movement (muscles).</p></li><li><p>Vision (lens of our eyes is pure crystalline protein).</p></li></ul></li></ul><h4 id="129b6996-4e1a-42df-bc82-f2a2311cca93" data-toc-id="129b6996-4e1a-42df-bc82-f2a2311cca93" collapsed="false" seolevelmigrated="true">Denaturation</h4><ul><li><p>Denaturation is a process in which proteins or nucleic acids lose their tertiary and secondary structure.</p></li><li><p>Caused by external stress or compounds such as:</p><ul><li><p>strong acids or bases.</p></li><li><p>concentrated inorganic salts.</p></li><li><p>organic solvents (e.g., alcohol or chloroform).</p></li><li><p>heat.</p></li></ul></li><li><p>Denaturation disrupts cell activity and can cause cell death.</p></li><li><p>Denatured proteins can exhibit loss of solubility or communal aggregation.</p></li></ul><h3 id="f648a1fb-bea7-4e60-8dd0-dfed1429f6d6" data-toc-id="f648a1fb-bea7-4e60-8dd0-dfed1429f6d6" collapsed="false" seolevelmigrated="true">Mechanism of Organic Chemical Reactions</h3><ul><li><p>A reaction mechanism is the step-by-step sequence of elementary reactions by which an overall chemical change occurs.</p></li><li><p>It describes in detail what takes place at each stage of an overall chemical reaction (transformation).</p></li><li><p>It describes each reaction intermediate, activated complex, and transition state.</p></li><li><p>It shows which bonds are broken (and in what order) and which bonds are formed (and in what order).</p></li><li><p>A complete mechanism accounts for all reactants used, the function of a catalyst, stereochemistry, all products formed, and the amount of each.</p></li><li><p>It also details the relative rates of the steps.</p></li><li><p>Reaction intermediates are chemical species, often unstable and short-lived, that are not reactants or products of the overall reaction but are temporary products and reactants in the mechanism's reaction steps.</p></li><li><p>Reaction intermediates are often free radicals or ions.</p></li><li><p>Transition states are unstable intermediate molecular states in elementary reactions.</p></li><li><p>Transition states involve an unstable number of bonds and/or unstable geometry at chemical potential maxima.</p></li></ul><p><em>SN2 example shown in transcript</em></p><ul><li><p>There is no limit to the number of possible organic reactions and mechanisms.</p></li><li><p>However, certain general patterns are observed to describe many common or useful reactions.</p></li><li><p>Each reaction has a stepwise reaction mechanism that explains how it happens, although this detailed description of steps is not always clear from a list of reactants alone.</p></li></ul><h4 id="b52d9a07-3b8f-4270-b0a9-0e4567046326" data-toc-id="b52d9a07-3b8f-4270-b0a9-0e4567046326" collapsed="false" seolevelmigrated="true">Basic Types of Organic Reactions</h4><ul><li><p>Organic reactions can be organized into several basic types; some reactions fit into more than one category.</p><ul><li><p>Substitution: Replacement of one atom or group with another.</p></li><li><p>Addition: Combining two reactants to form a single product.</p></li><li><p>Elimination: Removing atoms or groups from a molecule to form a multiple bond.</p></li><li><p>Rearrangement: Changing the connectivity of atoms in a molecule.</p></li></ul></li></ul><h3 id="a1cfea51-31c7-4d72-8a55-0a037c3a44f0" data-toc-id="a1cfea51-31c7-4d72-8a55-0a037c3a44f0" collapsed="false" seolevelmigrated="true">Carboxylic Acids</h3><ul><li><p>Carboxylic acids are organic acids characterized by the presence of at least one carboxyl group.</p></li><li><p>The general formula of a carboxylic acid is R-COOH.</p></li><li><p>A carboxyl group (or carboxy) is a functional group consisting of a carbonyl (RR'C=O) and a hydroxyl (R-O-H), which has the formula -C(=O)OH, usually written as -COOH.</p></li><li><p>Carboxylic acids are Bronsted-Lowry acids; they are proton donors.</p></li><li><p>They are the most common type of organic acid.</p></li><li><p>Examples:</p><ul><li><p>Formic acid (H-COOH): Occurs in ants.</p></li><li><p>Acetic acid (CH_3−COOH):Givesvinegaritssourtaste.</p></li></ul></li><li><p>Acidswithtwoormorecarboxylgroupsarecalleddicarboxylic,tricarboxylic,etc.</p><ul><li><p>Oxalicacid(COOH)2:Simplestdicarboxylicacid.</p></li><li><p>Melliticacid:Exampleofahexacarboxylicacid.</p></li><li><p>Citricacid(inlemons)andtartaricacid(intamarinds):Othernaturalexamples.</p></li></ul></li><li><p>ThecarboxylateanionR−COO−isusuallynamedwiththesuffix−ate(e.g.,aceticacidbecomesacetateion).</p></li><li><p>InIUPACnomenclature,carboxylicacidshavean−oicacidsuffix(e.g.,octadecanoicacid).</p></li><li><p>Incommonnomenclature,thesuffixisusually−icacid(e.g.,stearicacid).</p></li></ul><h4id="8d3720da−5686−4915−9f32−287fbd260462"data−toc−id="8d3720da−5686−4915−9f32−287fbd260462"collapsed="false"seolevelmigrated="true">CommonCarboxylicAcids</h4><p>Formicacid(H−COOH):Occursinants.</p><ul><li><p>Properties:Colorlessliquidwithapungentodor.Strongreducingagent.</p></li></ul><p>Aceticacid(<span>CH3</span><spanstyle="font−family:KaTeXMath"><em>CH</em></span><span>3​</span>−COOH):Givesvinegaritssourtaste.</p><ul><li><p>Properties:Clear,colorlessliquidwithastrong,vinegar−likeodor.Misciblewithwater,alcohol,ether,andglycerol.</p></li></ul><p>Oxalicacid<span>(COOH)2(</span><spanstyle="font−family:KaTeXMath"><em>COOH</em></span><span>)2​</span>:Simplestdicarboxylicacid.</p><ul><li><p>Properties:Crystallinesolid,formsadihydrate.Reducingagent.</p></li></ul><p>Salicylicacid</p><ul><li><p>Properties:Whitecrystallinesolid.Slightlysolubleinwaterbutsolubleinalcoholandether.</p></li></ul><h4id="61eacaea−fc5e−451c−bf87−75b697633fbd"data−toc−id="61eacaea−fc5e−451c−bf87−75b697633fbd"collapsed="false"seolevelmigrated="true">Production</h4><ul><li><p>Oxidationofaldehydeswithairusingcobaltandmanganesecatalysts:<br><em>Alkane−>primaryAlcohol−>Aldehyde−>Carboxylicacid</em></p></li><li><p>Oxidationofketones:<br>CH<em>3COCH</em>3→oxidationCH3COOH+HCOOH-COOH): Gives vinegar its sour taste.</p></li></ul></li><li><p>Acids with two or more carboxyl groups are called dicarboxylic, tricarboxylic, etc.</p><ul><li><p>Oxalic acid (COOH)2: Simplest dicarboxylic acid.</p></li><li><p>Mellitic acid: Example of a hexacarboxylic acid.</p></li><li><p>Citric acid (in lemons) and tartaric acid (in tamarinds): Other natural examples.</p></li></ul></li><li><p>The carboxylate anion R-COO- is usually named with the suffix -ate (e.g., acetic acid becomes acetate ion).</p></li><li><p>In IUPAC nomenclature, carboxylic acids have an -oic acid suffix (e.g., octadecanoic acid).</p></li><li><p>In common nomenclature, the suffix is usually -ic acid (e.g., stearic acid).</p></li></ul><h4 id="8d3720da-5686-4915-9f32-287fbd260462" data-toc-id="8d3720da-5686-4915-9f32-287fbd260462" collapsed="false" seolevelmigrated="true">Common Carboxylic Acids</h4><p>Formic acid (H-COOH): Occurs in ants.</p><ul><li><p>Properties: Colorless liquid with a pungent odor. Strong reducing agent.</p></li></ul><p>Acetic acid (<span>CH3</span><span style="font-family: KaTeX_Math"><em>CH</em></span><span>3​</span>-COOH): Gives vinegar its sour taste.</p><ul><li><p>Properties: Clear, colorless liquid with a strong, vinegar-like odor. Miscible with water, alcohol, ether, and glycerol.</p></li></ul><p>Oxalic acid <span>(COOH)2(</span><span style="font-family: KaTeX_Math"><em>COOH</em></span><span>)2​</span>: Simplest dicarboxylic acid.</p><ul><li><p>Properties: Crystalline solid, forms a dihydrate. Reducing agent.</p></li></ul><p>Salicylic acid</p><ul><li><p>Properties: White crystalline solid. Slightly soluble in water but soluble in alcohol and ether.</p></li></ul><h4 id="61eacaea-fc5e-451c-bf87-75b697633fbd" data-toc-id="61eacaea-fc5e-451c-bf87-75b697633fbd" collapsed="false" seolevelmigrated="true">Production</h4><ul><li><p>Oxidation of aldehydes with air using cobalt and manganese catalysts:<br><em>Alkane -> primary Alcohol -> Aldehyde -> Carboxylic acid</em></p></li><li><p>Oxidation of ketones:<br>CH<em>3COCH</em>3 \xrightarrow{oxidation} CH_3COOH + HCOOH
    Acetone yields acetic acid and formic acid

  • Nitrile hydrolysis:
    R-C≡N + 2H2O \rightarrow R-COOH + NH3</p></li></ul><h3id="73cbcf7a−aa48−4672−bd4f−c58db3dc8a8e"data−toc−id="73cbcf7a−aa48−4672−bd4f−c58db3dc8a8e"collapsed="false"seolevelmigrated="true">PropertiesofCarboxylicAcids</h3><h4id="9224557d−410f−492e−ac7d−d257a7a90dfd"data−toc−id="9224557d−410f−492e−ac7d−d257a7a90dfd"collapsed="false"seolevelmigrated="true">PhysicalProperties</h4><ul><li><p>Smallercarboxylicacids(1to5carbons)aresolubleinwater.</p></li><li><p>Highercarboxylicacidsarelesssolubleduetotheincreasinghydrophobicnatureofthealkylchain.</p></li><li><p>Longer−chainacidsaresolubleinless−polarsolventssuchasethersandalcohols.</p></li><li><p>Carboxylicacidshavehigherboilingpointsthanwater.</p></li><li><p>Carboxylicacidsoftenhavestrongodors,especiallythevolatilederivatives(e.g.,aceticacidinvinegarandbutyricacidinrancidbutter).</p></li><li><p>Estersofcarboxylicacidstendtohavepleasantodorsandareusedinperfumes.</p></li></ul><h4id="67cce7eb−84fc−4240−b0c3−8c6e30d1b292"data−toc−id="67cce7eb−84fc−4240−b0c3−8c6e30d1b292"collapsed="false"seolevelmigrated="true">ChemicalProperties</h4><ul><li><p>Aceticacidreactswithalkaliestoformcorrespondingsalts.</p><ul><li><p>Aceticaciddonatesaprotonandformssaltswithbases,showingitsacidicnature:<br>2CH<em>3COOH+2Na→2CH</em>3COONa+H<em>2</p></li></ul><h3 id="73cbcf7a-aa48-4672-bd4f-c58db3dc8a8e" data-toc-id="73cbcf7a-aa48-4672-bd4f-c58db3dc8a8e" collapsed="false" seolevelmigrated="true">Properties of Carboxylic Acids</h3><h4 id="9224557d-410f-492e-ac7d-d257a7a90dfd" data-toc-id="9224557d-410f-492e-ac7d-d257a7a90dfd" collapsed="false" seolevelmigrated="true">Physical Properties</h4><ul><li><p>Smaller carboxylic acids (1 to 5 carbons) are soluble in water.</p></li><li><p>Higher carboxylic acids are less soluble due to the increasing hydrophobic nature of the alkyl chain.</p></li><li><p>Longer-chain acids are soluble in less-polar solvents such as ethers and alcohols.</p></li><li><p>Carboxylic acids have higher boiling points than water.</p></li><li><p>Carboxylic acids often have strong odors, especially the volatile derivatives (e.g., acetic acid in vinegar and butyric acid in rancid butter).</p></li><li><p>Esters of carboxylic acids tend to have pleasant odors and are used in perfumes.</p></li></ul><h4 id="67cce7eb-84fc-4240-b0c3-8c6e30d1b292" data-toc-id="67cce7eb-84fc-4240-b0c3-8c6e30d1b292" collapsed="false" seolevelmigrated="true">Chemical Properties</h4><ul><li><p>Acetic acid reacts with alkalies to form corresponding salts.</p><ul><li><p>Acetic acid donates a proton and forms salts with bases, showing its acidic nature:<br>2CH<em>3COOH + 2Na \rightarrow 2CH</em>3COONa + H<em>2 $$CH3COOH + NaOH \rightarrow CH3COONa + H2O

  • The most important reactions of carboxylic acids are the substitutions of the hydroxyl group with other functional groups.

  • Corresponding derivatives:

    • Acyl halide: R-COX (X = F, Cl, Br, or I)

    • Anhydride

    • Ester: R-COOR' (R' = H or alkyl)

    • Amide: NR2

    • Nitrile: R-C≡N

    • Examples provided in transcript

    Reduction of Carboxylic Acids

    • Reduction of acetic acid:
      CH3COOH \xrightarrow{Red.} CH3CHO\xrightarrow{Red.} CH3CH2OH
      Acetic acid to ethanal to ethanol