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functional group of aldehydes and ketones
carbonal
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C is joined to O with
a double bond
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aldehyde structure
- ---CHO
- written like this because otherwise it could look like an alcohol
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ketone structure
- --CO--
- double bond not shown but assumed
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aldehyde general formulas
- H-C(=O)-H
- R-C(=O)-H
- Ar-C(=O)-H
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aldehydes come from
- alcohol dehydrogenation
- (remiving a hydrogen from an alcohol)
- same thing as oxidation
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- formaldehyde methanal (IUPAC)
- smallest aldehyde
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- acetaldehyde ethanal
- (IUPAC)
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naming aldehydes
- longest chain with carbonal group
- carbonal group gets #1 position but NO NEED TO # because it's always on the end
- drop the e and add "al"
- aldehydes get preferance over all groups named so far
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- benzaldehyde
- only name
- common name but recognized by the IUPAC
- use O,M, or P to indicate position of another group
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ketone general formulas
- R-C(=O)-R
- R-C(=O)-Ar
- Ar-C(=O)-Ar
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naming ketones
- drop e, add "-one"
- only add # of group position if parent has FIVE or more carbons
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most simple ketone
acetone
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acetone other names
- dimethyl ketone (common)
- propanone (IUPAC)
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ethyl methyl ketone give IUPAC
butanone
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diethyl ketone -give IUPAC
3-pentanone
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boiling points of aldehydes and ketones are
more than ethers and less than alcohols
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odors of aldehydes and ketones
- low aldehydes: pungent odors
- high aldehydes: pleasant odors
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solubility of aldehydes and ketones
- similar to alcohols
- 1-4 carbons are soluable
- solubility decreases as # of carbons increases
- (C-H bonsa are nonpolar and not soluable, unlike hydrogen bonds)
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oxidation of alcohols to carboxylic acids
- KETONES CAN'T BE OXIDIZED
- Primary:
- -adds a =O to where the -OH is
- -acid catalyst
- -oxidizing agent: CO3
- -solvents: pyridine, CH2Cl2
- (top) CrO2/H+------>(bottom) pyridine/CH2Cl2
- Secondary:
- -uses chromium compounds and sulfuric acid
- -acid catalyst such as H2SO4
- -oxidizing agent: K2Cr2O7 or CrO2
- -(top) CrO2/H+------>(bottom)H2SO4
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aldehydes and ketones both
combust
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common oxidizing agents for aldehydes
- Tollen's Reagent
- agent: Ag+
- complexing agent: NH3 (ammonia)
- positive aldehyde test: free silver mirrors
- Benedict's Regent
- agent: Cu+2
- complexing agent: citrate
- positive aldehyde test: Cu2O
- Fehling's Reagent
- agent: Cu+2
- complexing agent: tartrate
- positive aldehyde test: Cu2O
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When Tollen's reagent oxidizes an aldehyde to produce a ________, the ____ ions are reduced to ________ _________.
- carboxylic acid; Ag+; free silver
- this method used to silver mirrors
- glucose used because of its aldehyde functional group
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The _____ in Benedict AND Fehling's reagents is reduced to _____ which is _____.
Cu+2; Cu2O; red
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H2 used to reduce aldehydes and ketones to alcohols
- reduction
- oposite of oxidation
- metal catalyst like platnium
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hydration of aldehydes and ketones
- add H2O
- formaldehyde easily dissolves so easily hydrated
- acetaldehyde does too to an extent
- forms hydrates
- -take a group with an =O, add the H2O, add one H to the O and add another -OH group, removing the =O and making it an -OH with another -OH group too
- the more carbons, the less something can hydrate
- percentages tell us how much of each thing is left after a reaction
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Methanal, AKA and about:
- AKA formaldehyde
- irritating odor
- formalin is a 40% aqueous soloution of formaldehyde (it can be like a 99% reacted reaction but 40% water)
- starting material for polymers and protiens
- denatures protiens and makes them insoluable in water and resistant to bacterial decay
- -embalming fluid
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Ethanal, AKA and about:
- AKA acetaldehyde
- volatile liquid
- produced by oxidation of ethanol
- produces acedic acid (vinegar)
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Propanone, AKA and about:
- AKA acetone
- liquid
- good solvent: mixes with water and most organic compounds
- mediator
- nail polish remover
- formed as a by product of lipid metabolism but futher oxidizes to CO2 and H20
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2,3 butandione is used in
butter
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cis-3-hexenal is found in
leaves
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combustion
add O2, products are CO2 and H2O
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