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Home , Alkane, Alkene, Alkyne, Propadiene, Triple bond

Chapter 12 , , and Aromatic Compounds

Compounds with multiple bonds

The most important compound with a is ethyne also known as ; it is used in the oxy acetylene torch.

Bombykol, is another natural product that contains double bonds. We will examine the structure of these materials shortly Compounds of and with less tha 2n+ 2 other than cyclic

Is there any other way of satisfying the octet for carbon in a with a formula

C2H4 or C2H2? How many groups around each C? 3 (bonding are not considered to be a group) H H C :: C H H What’s the geometry? triangular

How about C2H2?

How many groups around each C? 2 CH ≡ HC

What’s the geometry? linear ethene or

What does ethylene have to do with fruit? A systematic way of naming alkenes and identifying identical structures

1. Locate the longest carbon chain in the molecule that contains the double bonds: this identifies the parent

2. Identify the points of branching and count the number of in each branch; name the branches in the normal way: methyl, ethyl ... 3. Give the the lowest number 4. Identify any

parent: 4 carbons: CH2 CH3 groups: 2 carbons: ethyl H2C C location: double bond at position 1; ethyl at 2 CH2

CH3 2-ethyl-1-butene no stereochemistry to describe Are these two compounds the same?

All these formulas for are identical because of rapid rotation about C-C bonds

If the two groups are on the same side of the double bond, use cis On opposite sides, use trans no, rotation about C=C bonds does not occur CH2-CH3 CH parent: H2C CH2 groups: ethyl, chloro

H2C CH location: 1, 3 CH2 Cl

CH2CH3 CH2CH3

Cl Cl

The solid wedge is used to denote a group sticking out of the plane of the screen A dotted wedge is used to denote a group sticking out of the plane of the screen

Two groups with the same relative orientation is called cis Two groups with the opposite relative orientation is called trans Naming compounds with double and triple bonds

generic names H3C CH3 ethene or ethylene alkene H2C CH2

ethyne or acetylene H CHC

H H CC CH3 CH3 cis 2-butene H CH2CH3 H H H H 1-butene

H CH2CH3 CH3 H trans 2-butene

H CH3

H CC CH2CH3 1-

CH3 CC CH3 2-butyne H CH2CH2CH2CH3 Name the following: CC CH3CH2 CH H

CH3 parent: groups: methyl, double bond location: 3-methyl, 4-double bond stereochemistry: trans

trans 3-methyl-4-nonene

H CH3 C H2C CH parent:

H2C CH groups: methyl CH2 location: 1, 3 or 1,2? shorthand notation 3-methyl-1-cyclohexene or 1-methyl-2-cyclohexene A is a chemical messenger emitted by insects in minute quantities.

Bombykol is emitted by the silkworm moth to attract other moths and has one cis and one trans double bond

16 C: parent alkane 2 double bonds : drop the last e and add ol stereochemistry: cis and trans (CH2)7 means 7 CH2 groups in a row To name this compound we need to know how to name a compound with 16 carbon How to name compounds with more than one double bond How to name and how to designate “stereochemistry” (the arrangement of groups in space: trans10, cis 12-hexadecadien-1-ol Name the following:

Br Br parent: ethene cis-1,2-Dibromoethene groups: bromo A. CC location 1,2 H H stereochemistry cis :

CH3 H CC parent: butene trans-2-Butene B. groups: double bond H CH3 location: 2 stereochemistry: trans CH3 Cl parent: C. CC groups: chloro location: 1,1-Dichloropropene H Cl 1,1 stereochemistry: none CH3 CH3 CH C 2 CH3 CH C CH CH CH3 2 CH2 CH2 parent: parent: groups: groups: location location stereochemistry: stereochemistry:

CH3 C C C C

Basic carbon framwork of many natural products CH3 CH3 H C H H C H C C C C

C CH C CH2 2 H CH H CH CH CH CH CH CH3 3 3 CH3

2 -methyl-5-isopropyl-1,3-cyclohexadiene Dill Anethum graveolens (Umbelliferae) Dill is a thin, annual originating in the Middle East. Since recorded history it has been cultivated as a medicinal and aromatic herb. It was spread through Europe by way of the monasteries. The picture on the left shows a 'broad-leafed' variety, the original type has completely thready leaflets. The fresh dill leaves and flowers contain an essential whose main component is (-)-alpha-phellandrene (ca. 60 %). Draw structures for the following compounds:

1- 2-methyl-1,7-octadiene 1,2- Compounds of carbon with multiple bonds to other elements

Oxygen double bonded to carbon is called a (C=O)

If the carbon of the carbonyl group is attached to two other carbon atoms the compound is called a ,

An contains a carbonyl group (C=O), which is a carbon with a double bond to an atom, attached to at least one hydrogen. O Carboxylic contain the carboxyl group, which is a carbonyl group attached to a hydroxyl group. O

acetic or ethanoic acid

In an , the hydrogen on oxygen is replaced by a carbon atom.

A attached to a carbonyl group is called an ; the other two groups attached to nitrogen can be either both N carbons, hydrogens or a mix of both carbon and hydrogen A few reactions of unsaturated compounds:

Adding H2 to double bonds in vegetable produces compounds with higher melting points solids at room temperature, such as , soft margarine, and shortening.

This makes them less reactive and less prone to become rancid; rancidness is due to reaction of the double bonds with oxygen

O CH3CH2CH2 C OH

CH3CH2CH2 O H CH3CH2CH2 C O CH2 O CH OCCH CH CH CH 2 2 2 2 2 C O CH OCCH CH CH CH H 2 2 2 2 2 CH2 CH3CH2CH2CH2CHC 2O CH +H2 (catalyst) H CH3CH2CH2CH2CHC 2O CH CH2OCCH2CH2CH2CH2 C H CH2OCCH2CH2CH2CH2 CH2 C O CH2 O CH2CH2CH2CH3 CH2CH2CH2CH3 unsaturated triglyceride saturated triglyceride are large, long-chain ; they are found in nature, including cellulose in plants, starches in food, and proteins and DNA in the body; they are also made synthetically, such as and polystyrene, Teflon, and they are made up of small repeating units called monomers that are often alkenes F F Teflon CF2CF2CF2CF2CF2 F F

Polypropylene CH3 H CHCH2CHCH2CHCH2CHCH2

H H CH CH CH3 CH3 3 3

Cl H Polyvinyl chloride CHCH2CHCH2CHCH2CHCH H H Cl Cl Cl Cl Recycling is simplified by using codes found on items. Aromatic Compounds

H

H C H C C

C C H C H

H

Different ways of representing the molecule

Molecules that contain a benzene ring are often referred to as aromatic compounds, originally because of their odor CH3 NH2 OH

methylbenzene () aminobenzene (aniline) hydroxybenzene (phenol)

OH OH

C H H H C H C C C C

C C C C H H H C H C

CH3 CH2CH2CH3 O O OH O OH OCH3 C C C-OH C C C H CH H OH H OH H CH C C C C C C C C

C C C C C C C C C H C H H H H H H C H C H H H H benzoic acid salicylic acid methyl salicylate benzaldehyde 2-hydroxybenzoic acid methyl 2-hydroxybenzoate

1-methyl,2,4,6-trimethylbenzene acetosalicylic acid 4-hydroxy-3- methoxybenzaldehyde H H Cl

H H H H

H H H H

HH Cl

1,4-dichlorobenzene benzo[a]