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 group

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 the realm of biochemistry is _____

the acetyl group, where R specifically represents 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:

• X is either a H or C atom

• C—X is a non-polar covalent bond

carboxylic acid, ester, amide have these similar properties

• X is an EN element and either an O or N atom

• C—X 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 _____

hydrogen atom and either another hydrogen, 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 _____

alkyl, aryl, or their combinations but not a hydrogen atom — these two groups can be the same or different.

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 begins 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 ____. Consequently, the boiling points of aldehydes and ketones are ____.

• polar

• dipole-dipole interactions within aldehydes and ketones.

• 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

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

Boiling points of ketones are _____ than aldehydes

higher

ketones are 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.