Lecture 11 Monday 2/8/17

ALCOHOL REACTIONS (continued)

PROPERTIES OF ETHERS Much less polar than More soluble in water than __________ but less soluble than ___________

PROPERTIES OF ETHERS (continued) Hydrogen bonding of dimethyl ether: (a) with water and (b) no hydrogen bonding in the pure state.

THIOLS: THE –SH (SULFHYDRYL) GROUP Most distinguishing characteristic ethanethiol – propanethiol – 1-propene-3-thiol and 3,3-di-(1-propenyl)disulfide – trans-2-butene-1-thiol, 3-methyl-1-butanethiol, and methyl-1-(trans-2-butenyl)disulfide –

THIOL REACTIONS Oxidation forms disulfide (-S-S-) linkages, which are important structural features of some proteins: Specific example:

THIOL REACTIONS (continued) Oxidation reactions can be reversed with a reducing agent (H), such as H2, which regenerates the thiol:

THIOL REACTIONS (continued) Thiols react with heavy metals (Pb2+, Hg2+) to form insoluble compounds, with adverse biological results:

POLYFUNCTIONAL COMPOUNDS Polyfunctional compounds are compounds with two or more functional groups. Functional groups determine chemical properties of compounds. Example:

POLYFUNCTIONAL COMPOUNDS (continued)

Chapter 14 Aldehydes and ketones

ALDEHYDES AND KETONES _____________________ have at least one hydrogen attached to the carbonyl group. ________________ have two carbons attached to the carbonyl group.

ALDEHYDES AND KETONES (continued) Examples:

NAMING ALDEHYDES Find the longest carbon chain that contains the aldehyde group. (The carbonyl carbon is carbon number 1.) Change ending of the root hydrocarbon name by dropping –e and adding –al. All other branches and groups are named and located using standard IUPAC system. Examples:

COMMON ALDEHYDES

NAMING KETONES Find the longest chain that contains C=O. Using the root alkane name, drop the –e ending and change to –one. Number the longest carbon chain so the C=O group has the lowest number. Name and number other attached groups as before. Examples:

COMMON KETONES

PHYSICAL PROPERTIES The carbonyl group is moderately polar, but it doesn’t have any hydrogen atoms bonded to the oxygen atom, so it cannot hydrogen bond between molecules.

PHYSICAL PROPERTIES (continued) Because of the polarity of the C=O group, these groups can interact, but the attraction is not as strong as hydrogen bonding. This makes the boiling point of aldehydes and ketones ___________ than alkanes, but _________ than alcohols.

PHYSICAL PROPERTIES (continued)

PHYSICAL PROPERTIES (continued) The C=O group can hydrogen bond with water molecules because the oxygen atom in the carbonyl group has a partial negative charge that attracts the partial positive charge of a hydrogen atom in the water molecule. This makes low molecular weight aldehydes and ketones water soluble (they have small hydrophobic sections).

PHYSICAL PROPERTIES (continued)

ALDEHYDE AND KETONE REACTIONS Recall the oxidation of alcohols produces aldehydes and ketones.

ALDEHYDE AND KETONE REACTIONS (continued) The difference in reactivity toward oxidation is the chief reason why aldehydes and ketones are classified in separated families.

ALDEHYDE AND KETONE REACTIONS (continued) The ease with which aldehydes are oxidized allows us to test for the presence of aldehydes with

ALDEHYDE AND KETONE REACTIONS (continued) In the presence of aldehydes

ALDEHYDE AND KETONE REACTIONS (continued)