CH16: ALDEHYDES & KETONES

OSU BIOPHRM 3311

The _____ is characterized by a carbon atom forming a double bond with an oxygen atom, accompanied by two single bonds.

carbonyl group

name of C on carbonyl group

carbonyl carbon

name of O on carbonyl group

carbonyl oxygen

carbonyl group adopts a ____ shape, with all 3 bond angles around the atoms measuring approximately ____degrees.

• planar triangular

• 120°

double bond (C=O) is polar (covalent bond) in nature, resulting from the ______

electronegativity disparity — carbonyl oxygen holds higher electron density (δ-) while the carbonyl carbon is relatively electron-deficient (δ+)

The C=C is more polar than the single bond C-C due to there being _____.

more e- w/in the double bond (4) vs. the single bond (2). The e- are pulled towards the O atom and the C becomes less negative!

ID this structure

acyl group

ID this structure

acetyl group

ID this structure

carbonyl compound

ID this structure

aldehyde

An acyl group consists of _____

an R group bonding to the carbonyl group. R may represent hydrogen, alkyl or aryl.

An essential acyl group in biochemistry is _____

the acetyl group, in which the R-group is a methyl group.

5 families of carbonyl compounds

aldehyde, ketone, carboxylic acid, ester, amide

The smallest ketone is _____

acetone - very good solvent; used in nail care routines

what are the two distinct groups of carbonyl compounds?

1. aldehydes and ketones

2. carboxylic acid, ester, amide

aldehyde and ketones have these similar properties:

Carbonyl C is bonded to either a H or C and that bond is non-polar covalent

carboxylic acid, ester, amide have these similar properties

Carbonyl C is bonded to EN element, either O or N, and it is a polar covalent bond

ID this structure by its common name

formaldehyde

ID this structure by its common name

acetaldehyde

ID this structure by its common name

benzaldehyde

An aldehyde contains a carbonyl group (C=O) with the carbonyl carbon bonded to a _____

H atom and either another H or an alkyl group or an aryl group.

The molecular formula of aldehyde is _____

R-CHO (not R-COH, that is Alcohol!).

common and IUPAC name of the smallest aldehyde

• formaldehyde

• methanal

common name of the second smallest aldehyde

acetaldehyde

ID this structure

ketone

ID this structure

acetone

In a ketone, the carbonyl group is attached to two organic groups, which can be _____

same or different alkyl, aryl, or their combinations but not a hydrogen atom

The general formula of ketones is _____.

RCOR’

Small aldehydes are often known by their common names, which end in_____.

-aldehyde. 

IUPAC naming of simple aldehydes: the final -e of the name of the alkane is replaced by___,

-al

IUPAC naming of simple aldehydes: The aldehyde functional group is always at _____

the end of a carbon chain. Therefore, we do not use 1 to indicate its position is on carbon number 1.

Common Names of Simple Ketones: Consider the smaller alkyl as the ____ and the larger alkyl as the ____.

• substituent

• parent

IUPAC Names of Simple Ketones: Number the alkane chain beginning at the _____

end nearest to the carbonyl group.

IUPAC Names of Simple Ketones: Replacing the final -e of the corresponding alkane name with _____

-one (pronounced own).

IUPAC Names of Simple Ketones:  Number to indicate the location of the _____.

ketone group

Naming Aldehydes and Ketones in the Same Molecule: Molecules, which contain both aldehyde and ketone groups, are named as _____.

aldehydes (due to higher ranking) with the prefix of a ketone substituent being "oxo".

Naming Aldehydes and Ketones in the Same Molecule: the aldehyde gets ___ and the ketone gets ___.

• no number to indicate location — since it is always at the end and therefore “1”.

• does get a location number!

The root names of aldehydes and ketones are derived from the _____

longest continuous chain of carbon atoms that bonds the functional groups.

The carbonyl group is _____, resulting in ____ interactions within aldehydes and ketones. Consequently, the boiling points of aldehydes and ketones are ____.

• polar

• dipole-dipole

• higher than alkanes of similar size

H must bond with an ____ in order to h-bond

EN atom

Given that aldehydes and ketones do not establish hydrogen bonds within their own kind, their boiling points typically ____.

fall below those of similarly sized alcohols.

boiling points ranked amongst ketones, aldehydes, alkanes, and alcohols, plus h-bonding ability w/ itself

[highest BP]…Alcohol (h-bonding ability) > Aldehyde/Ketone (nope) > Alkane (nada)…[lowest BP]

Boiling points of ketones are _____ than aldehydes

higher

are ketones more or less polar than aldehydes? why?

more polar — two electron-donating alkyl groups in ketones increase the partial positive charge on the carbonyl carbon, strengthening dipole–dipole interactions.

which has the stronger dipole-dipole and LDFs, aldehydes or ketones?

ketones! = higher BPs!

recite which intermolecular forces are contained in alkanes, aldehydes, ketones, and alcohols

Intermolecular forces	Alkane	Aldehyde / Ketone	Alcohol
London forces	+	+	+
Dipole-dipole		+	+
Hydrogen bonding			+

The polar carbonyl group in aldehydes and ketones allows their oxygen to form ____.

hydrogen bonds with water.

Ketones are more polar and water soluble than aldehydes due to _____.

their electron-rich R groups.

Small aldehydes and ketones are soluble in water, but solubility decreases with ____

increasing carbon chain length (increasing nonpolar parts), becoming insoluble for compounds with more than 5-6 carbons.

Slightly larger partial negative charge on the ketone indicates ______.

a more polar structure, which means more water soluble!

Alkyl groups are _______ groups.

electron-donating

ketones are more polar than aldehydes b/c _________.

alkyl groups are electron-donating groups. 

The solubility of ketones is ______ than aldehydes with the same number of carbons.

higher

Miscible definition

completely soluble in water

Ketones are _______ than aldehydes

more water soluble

When the compound gets larger, the proportion of the ___________ increases

non-polar part

Boiling point _______ as the molecule gets larger due to ______.

• increases

• more London dispersion force

Water solubility _____ as the proportion of the nonpolar part increases

decreases

Due to hydrogen bonding, small (with 2-3 carbons) alcohols, aldehydes or ketones are _______ in water.

soluble

Aldehyde and ketone are polar molecules due to the ________.

presence of the carbonyl group

Aldehydes and ketones cannot hydrogen bond with one another, their boiling points are _______ than alcohols but _______.

• lower

• higher than alkanes because of dipole-dipole interactions

Common aldehydes and ketones are typically ______.

liquids

ketones are good _____ for many polar and nonpolar solutes.

solvents

Many aldehydes and ketones have distinctive ______.

odors

Simple ketones are less ______ than simple aldehydes.

toxic

The molecular compound is named after the functional group with the _______!

highest ranking

Retinal definition

An aldehyde form of vitamin A (retinol) involved in vision and light perception in the retina of the eye.

Acetoacetate definition

A ketone body produced during the breakdown of fatty acids in the liver.

Estrone definition

a female sex hormone. Its chemical structure includes a steroid nucleus and a ketone functional group.

Glucose definition

6-C sugar w/ an aldehyde group, and a main energy source in the body

Ribose definition

5-C sugar w/ an aldehyde group and a component of RNA and ATP.

relationship b/t glucose and ribose

functional group constitutional isomers

relationship b/t fructose and ribulose

functional group constitutional isomers

Fructose definition

6-C sugar w/ a ketone group at C2

Ribulose definition

5-C sugar w/ a ketone group at C2, involved in photosynthesis and the pentose phosphate pathway.

Ketone bodies definition

Fat-derived, water-soluble fuels made in the liver for energy use by brain and heart.

ketone bodies’ names

• 3-Hydroxybutyrate

• acetoacetate

• acetone

acetoacetate is ____ to form acetone.

decarbonated (CO2 removed)

Aldehydes are formed by the_________.

oxidation of primary alcohols, which can be further oxidized to carboxylic acids

Ketones are formed by the _____.

oxidation of secondary alcohols, which do not undergo further oxidation reactions

ID this rxn

oxidation of primary alcohol w/ excess oxidizing agent to form, first an aldehyde, and then a carboxylic acid

ID this rxn

oxidation of secondary alcohol to form a ketone; excess oxidizing agent leads to no rxn

Reduction of aldehydes and ketones entails what?

• reverse of the oxidation of alcohols

• addition of a H atom to each atom of the carbonyl group

• leads to two different classes of alcohol

ID this rxn

general oxidation-reduction rxn for either aldehyde or ketone, where the forward arrow is the reduction and the reverse arrow is the oxidation

ID this rxn

reduction of aldehyde forming a primary alcohol

ID this rxn

reduction of ketones forming a secondary alcohol

Pyruvate is the end product of _____.

glycolysis (breakdown of glucose)

Under certain conditions, the ketone group in pyruvate is reduced to _____.

alcohol forming lactic acid

In our body, in biochemical rxns, the reduction of carbonyl groups is carried out by the reducing agent called ________.

nicotinamide adenine dinucleotide (NADH/H+)

when something is reduced, something else needs to be _______.

oxidized

ID the function of this structure 

reducing agent

ID the function of this structure

oxidizing agent

pyruvate to lactate is a _____ rxn.

reduction

the _____ nature of a carbonyl group allows aldehydes and ketones to undergo addition rxns w/ _____ instead of hydrogen

• unsaturated

• alcohol

hemiacetal definition

An intermediate product, formed when an alcohol adds to an aldehyde, creating a C bonded to an —OH, an —OR group, a H, and one alkyl (or aryl) group.

hemiketal definition

An intermediate product, formed when an alcohol adds to a ketone, creating a C bonded to an —OH, an —OR group, and two alkyl (or aryl) groups.

hemiacetal seen in ____ functional group

aldehydes

hemiketal seen in ___ functional group

ketones

In the carbonyl group, oxygen is more electronegative, creating a _____ on the oxygen atom and a _______ on the carbon atom.

• δ-

• δ+

Alcohol dissociates into ______.

H+ and alkoxy ion (RO-)