Ketones
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Ketones. Eden Ambrose Emily Deignan Meagan Clark. Definition of a Ketone. A KETONE IS…An organic compound characterized by the presence of a carbonyl group bonded to two carbon atoms in the middle of the carbon chain. . Structure.

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Ketones

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Ketones

Ketones

Eden Ambrose

Emily Deignan

Meagan Clark


Definition of a ketone

Definition of a Ketone

A KETONE IS…An organic compound characterized by the presence of a carbonyl group bonded to two carbon atoms in the middle of the carbon chain.


Structure

Structure

Ketones and aldehydes are extremely similar, except for the fact that the carbonyl group is in the middle of the chain in a ketone. In an aldehyde the carbonyl group is on the end of the carbon chain.

The carbonyl group consists of an oxygen atom bonded to a carbon atom with double bonds.

Ketones can be parts of aromatics and rings, they are not always in chains.

Acetanone

4-Ethyl-3-pentanone

Propanone


Basic nomenclature

Basic Nomenclature

  • First you need to find the longest carbon chain to find the alkane that is being used.

  • Ketones are named by taking away the –e ending from the alkane that is being used and adding the ending –one.

  • When the carbon chain has 5 or more carbons you must add the number in which the oxygen is off of.

  • You must number your carbon chain from the end that will give you the carbonyl group.

2-Pentanone

4-methylButanone

Propanone (Acetone)


Examples of nomenclature

Examples of Nomenclature

Name the Ketone

2,6-dimethyl-4-Heptanone

2-Heptanone

2-Hexanone


Examples of nomenclature1

Examples of Nomenclature

Butanone

5-methyl-2-Hexanone

4-methyl-2-Pentanone


Properties of aldehydes and ketones

Properties of Aldehydes and Ketones

C=O is a polar molecule due to the four shared electrons in the double C=O bond

C=O cannot hydrogen bond together but can accept hydrogen bonds from donors, ex. HOH (water)

As a result, Aldehydes and Ketones have higher melting and boiling points than analogous alkanes, but lower boiling points than analogous alcohols.

Also ketones are more soluble than alkanes but less soluble than alcohols in aqueous solutes, due to the fact they do not contain OH groups and therefore cannot hydrogen bond


Properties

Properties

As a result, Aldehydes and Ketones have higher melting and boiling points than analogous alkanes, but lower boiling points than analogous alcohols.

Table 1: Boiling Points of Analogous Compounds


Properties1

Properties

Also Ketones are more soluble than alkanes because they are polar molecules

Ketones are less soluble than alcohols in aqueous solutes, due to the fact they do not contain OH groups and therefore cannot hydrogen bond


Ketones

Uses

2-heptanone is a compound that ants use to warn off danger

Pheromones are more complex ketones that are used by many insects to enhance hormones [Ex: 9-ketodecenoic acid is used by honeybee queens to take flights]

Anti-inflammatory agents such as cortisone

Some steroids are also ketones

Parts of many hormones such as testosterone and progesterone


Oxidation reactions

Oxidation Reactions

An oxidation reaction is a chemical transformation involving a loss of electrons; used in organic chemistry involving the addition of oxygen atoms or the loss of hydrogen atoms

  • These processes are always accompanied by a reaction partner that undergoes, “reduction,” or gaining electrons during oxidation.


Ketones

Ketones can be prepared by the controlled oxidation of alcohols.

Alcohols burned in oxygen undergo complete oxidation, in which the only products formed are carbon dioxide and water

Oxidation reactions can be controlled to form other products and in these reactions oxygen atoms are supplied by oxidizing agents ex. Hydrogen peroxide- H2O2

  • The reactive O atoms removes two H atoms from an OH group in the alcohol, and one from the adjacent C atom, resulting in a C=O group, a water molecule is an additional product


Oxidation of primary secondary and tertiary alcohols

Oxidation of Primary, Secondary and Tertiary Alcohols

When a secondary alcohol is oxidized, the carbonyl group formed is necessarily attached to two alkyl groups forming a ketone

Secondary Alcohol Oxidation

Tertiary Alcohol Oxidation

Primary Alcohol Oxidation

When a primary alcohol is oxidized, an H atom remains bonded to the C atom and an aldehyde is produced

Tertiary alcohols cannot undergo this type of oxidation because no H atom is available on the central C atom


Hydrogenation reactions of ketones to alcohols

Hydrogenation Reactions of Ketones to Alcohols

C=O double bond in carbonyl groups can undergo addition reactions with hydrogen

The presence if high temperature, pressures and a catalyst are required for this reaction

H atoms are added to the carbonyl groups and OH group results- producing an alcohol.

This is essentially a reversal of an oxidation reaction

Ketones will always produce secondary alcohols


References

References

“Aldehydes and Ketones." Chapter 17: Aldehydes and Ketones. Nucleophilic Addition to C=O. The McGraw Hill Companies, 2000. Web. 27 Sept. 2011. <http://www.mhhe.com/physsci/chemistry/carey/student/olc/ch17aldehydeskeytones.html>.

Ball, David W. "The Basics of General, Organic and Biological Chemistry." Welcome | Flat World Knowledge. Web. 27 Sept. 2011. <http://www.flatworldknowledge.com>.

"Organic Chemistry." UCLA Chemistry and Biochemistry. UC Regents. Web. 27 Sept. 2011. <http://www.chem.ucla.edu>.

Shrestha, Binod. "Unit 12: Aldehydes and Ketones." Learners' Chemistry. Web. 27 Sept. 2011. <http://www.chem-guide.blogspot.com>.

Van, Kessel Hans. "Aldehydes and Ketones." Nelson Chemistry 12. Toronto: Thomson Nelson, 2003. Print.


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