ALDEHYDES AND KETONES

Aldehyde Ketone STRUCTURE

NOMENCLATURE

Choose the longest continuous carbon chain that contains the carbonyl carbon Number from the end of the chain closest to the carbonyl carbon Ketone ending is -one IUPAC Nomenclature of Ketones Do the ketones section of Organic Nomenclature program!

2-Pentanone EXAMPLES 4-Ethyl-3-hexanone

3-Isopropylcyclopentanone

Common, or Trivial, Names Name each group attached to the carbonyl group as an alkyl group Combine into a name, according to the pattern: alkyl alkyl’ ketone NOTE: This is not all one word! KETONES

Methyl propyl ketone Example of Common Names Diethyl ketone

acetone dimethyl ketone A common laboratory solvent and cleaning agent SPECIAL CASES benzophenone diphenyl ketone acetophenone methyl phenyl ketone KNOW THESE

Choose the longest continuous carbon chain that contains the carbonyl carbon Number from the end of the chain closest to the carbonyl carbon (carbon #1!) Aldehyde ending is -al IUPAC Nomenclature of Aldehydes Do the aldehydes section of Organic Nomenclature program.

EXAMPLES pentanal 2-chloro-3-methylbutanal always carbon 1 aldehyde group is

Common Names of the Aldehydes RECOGNIZE THESE

SPECIAL CASES formaldehydeacetaldehyde benzaldehyde KNOW THESE

Forming Common Names of Aldehydes  -chlorocaproaldehyde (  -chlorohexanal )  -chlorocaproaldehyde (  -chlorohexanal ) USE OF GREEK LETTERS …….  is always the end of the chain, no matter how long

REACTIVITY OF THE C=O GROUP NUCLEOPHILIC ADDITION

.. : ++ -- :: - + THE CARBONYL GROUP electrophilic at carbon nucleophilic at oxygen Nu: nucleophiles attack here H + or E + electrophiles add here GENERALIZED CHEMISTRY

NUCLEOPHILIC ADDITION TO C=O MECHANISMS IN ACID AND IN BASE

Nucleophilic Addition to Carbonyl Basic or Neutral Solution an alkoxide ion BASIC SOLUTION Good nucleophiles and strong bases (usually charged) - or on adding acid

Nucleophilic Addition to Carbonyl Acid Catalyzed Acid Catalyzed Acid catalysis speeds the rate of addition of weak nucleophiles and weak bases (usually uncharged). more reactive to addition than the un- protonated precursor ACIDIC SOLUTION (+) pH 5-6 stronger acid protonates the nucleophile

CYANOHYDRINS

A cyanohydrin Addition of Cyanide Buffered to pH 6-8 In acid solution there would be little CN -, and HCN (g) would be a problem (poison). a cyanohydrin :C N:

.. CYANIDE ION BONDS TO HEMOGLOBIN Cyanide bonds (irreversibly) to the site (Fe II) where oxygen usually bonds. CYANIDE IS IS A POISON You die of suffocation - lack of oxygen. HCN is a gas that you can easily breathe into your lungs...

ORGANOMETALLICS

(R-Li) Addition of Organometallic Reagents ether These reagents cannot exist in acid solution workup step alcohol :R - Synthesis of Alcohols

Summary of Reactions of Organometallics with Carbonyl Compounds Organometallics with ketones yield tertiary alcohols Organometallics with aldehydes yield secondary alcohols Organometallics with formaldehyde yield primary alcohols. Organometallics with carbon dioxide yield carboxylic acids. etc. All review to you

HYDRATES

hydrates are unstable and cannot be isolated in most cases Addition of Water most hydrates revert to an aldehyde or ketone as soon as they form aldehyde or ketone favored

.. : : + + ACID CATALYSIS +.. : :Nu Acid catalysis enhances the reactivity of the carbonyl group - nucleophilic addition proceeds more easily. weak nucleophiles can react RECALL Water is a weak nucleophile.

.. :: :: : a hydrate WATER ADDS TO THE CARBONYL GROUP OF ALDEHYDES AND KETONES TO FORM HYDRATES for most compounds the equilibrium favors the starting materials and you cannot isolate the hydrate catalyzed by a trace of acid In a reaction where all steps are reversible, the steps in the reverse reaction are the same as those in the forward reaction, reversed! MICROREVERSIBILITY:.. +

an excess of H 2 O 18 shifts the equilibrium to the right ISOTOPE EXCHANGE REVEALS THE PRESENCE OF THE HYDRATE OF THE HYDRATE 18 + H+H+ exchange shows the presence of a symmetric intermediate +H 2 O 18 -H 2 O excess

SOME STABLE HYDRATES chloral chloral hydrate cyclopropanone hydrate 120 o expected 60 o required 109 o expected 60 o required sp 2 sp 3 ++  these also indicate that hydrates are possible

SOME ADDITIONAL STABLE HYDRATES glyoxal phenylglyoxal

ACETALS AND HEMIACETALS

.. : : + + ACID CATALYSIS +.. : :Nu Acid catalysis enhances the reactivity of the carbonyl group - nucleophilic addition proceeds more easily. weak nucleophiles can react RECALL Alcohols are weak nucleophiles.

Addition of Alcohols addition of one mole addition of second mole hemiketal an aketal H+H+ H+H+ TWO MOLES OF ALCOHOL WILL ADD The equilibria normally favor the aldehyde or ketone starting material, but we will show how they can be made.

aldehyde ketone hemiacetalacetal (ketal)*(hemiketal)* ACETALS AND HEMIACETALS *older term

hemiacetal.. : :: : : : ACID CATALYZED FORMATION OF A HEMIACETAL Normally the starting material is favored - but a second molecule of alcohol can react if in excess (next slide) Like a hydronium ion first addition

acetal :.. : : : : : :: : : : : FORMATION OF THE ACETAL ( ) FORMATION OF THE ACETAL ( from the hemiacetal ) Resonance stabilized carbocation SN1SN1 second addition hemiacetal remove

STABILITY OF ACETALS AND HEMIACETALS Most hemiacetals are not stable, except for those of sugars (see later). Acetals are not stable in aqueous acid, but they are stable to aqueous base. AQUEOUS ACID AQUEOUS BASE no reaction H 2 SO 4 H2OH2O H2OH2O NaOH +

H2OH2O hydrate hemiacetalacetal R-O-H H2OH2O ADDITION OF WATER AND ALCOHOLS WATER ALCOHOLS no reaction NaOH H2OH2O H2OH2O H+H+ acetals are stable to base but not to aqueous acid

REAKSI OKSIDASI

OKSIDASI ALDEHID DAN KETON Keton tidak mudah dioksidasi Aldehid sangat mudah dioksidasi, menjadi asam karboksilat Zat pengoksidasi : KMnO4, H, H2O

Reaksi Reduksi

Reduksi aldehid menghasilkan alkohol primer Reduksi keton menghasilkan alkohol sekunder Zat pereduksi: H2, katalis Zn/Hg, HCl

Reaksi Adisi-eliminasi

Aldehid + Amina Primer Imina Aldehid + Amina sekunder Enamina Aldehid + Amina tersier hidrazon

Ramalkan produk hemiasetal atau hemiasetal siklik dari: 1.5-hidroksi-2-heksanon dengan air 2.1,3,4,5,6-pentahidroksi-2-heksanon dengan air 3.propanal dengan metanol 4.Aseton dengan 1,2,3-propanatriol

Ramalkan apa produk reaksi sikloheksanon dengan : 1.CH3NH2 2.(CH3)2NH