We look for a C atom that has four different groups attached.
The two compounds are shown.
The C atom in 2-chloropentane has four different groups attached.
3-chloropentane is achiral because it does not have a C atom and its structure is the same as its mirror image.
We focused on the carbons to which the atoms were attached in drawing the structures.
The other carbons cannot possibly be the same because they are all bonding to at least two H atoms.
A carbon atom has four different groups.
If there is a point of difference, the carbon atom is asymmetric.
If there is no substituent, the carbon atom has two hydrogen atoms and can't be chiral.
The path went to the methyl substituent.
We conclude that C1 is not a type of symmetry.
C1 is not the same as the other path.
We found that C3 is also chiral.
C1 and C3 are not straight.
In most of the examples we have considered, there is only one atom per molecule.
The molecules are active.
1,3-dimethylcyclohexane has two carbon atoms.
A molecule with two or more carbon atoms may or may not be active.
In advanced organic chemistry courses, the optical activity of molecule containing two or more chiral atoms is discussed.
The diagram on the right shows the carbon atoms in a molecule.
The rules for assigning priorities will be described soon.
There are two possible arrangements for the FIGURE 26-16 remaining substituents.
The enantiomer of 1-chloro atomic mass is different from the one shown below.
Priority I can be assigned by focusing on atomic mass.
The priority is established by the higher atomic number at this point.
An ethyl group takes priority over a methyl group.
At the point of attachment to the stereocenter each substituent has a C atom, equal in priority, beyond these C atoms, and the ethyl group has a higher-priority C atom.
The constitution of the rest of the chain is immaterial when that point has been reached.
The assignment of configuration is one of the compounds named.
The priorities of the substituents are the first thing we need to assign the configuration at the stereocenter.
C3 is the center of this molecule.
The first point of difference in the chains of these substituents is what determines the ranking of the ethyl group.
The molecule is 4-bromobutan-2-ol with C2 as the center.
The first point of difference in the chains of these substituents is what determines the ranking of the bromoethyl group.
It's not as easy to see the molecule toward the lowest priority H atom.
The H atom is in the plane of the paper and not far away from the viewers.
There are two ways to tackle this problem.
We can change a pair of groups so that the group with the lowest priority is bonds by a dashed wedge.
The group of lowest priority is where the view of the molecule should be drawn.
The priorities are counterclockwise.
We created the enantiomer because we switched groups.
To find the first point of difference and compare the atomic numbers of the atoms at that point, it may be necessary to assign priorities to groups.
A straight- or branched-chain alkane with formula CnH2n+2 has a maximum number of H atoms possible.
In other classes of hydrocarbons, compounds with the same number of C atoms but fewer H atoms must join into rings, form carbon-to-carbon multiple bonds, or do both to ensure that each C atom forms a total of four bonds.
Some aspects of ring structures have already been discussed.
Double or triple bonds between C atoms are found in some hydrocarbons.
The names for a few alkenes are given below.
The names in parentheses are used a lot.
The base chain is the longest chain with the multiple bond.
To place the multiple bond at the lowest possible number, you have to number the C atoms of the chain.
The double bond makes the molecule an alkene, and its location between the first and second carbon makes it a pent-1-ene.
The alkene is named 2-ethylpent-1-ene because the ethyl group is attached to the second C atom.
The alkenes and alkanes have similar physical properties.
Those with 2 to 4 C atoms are gases, those with 5 to 18 are liquids, and those with more than 18 are solids.
Alkynes have higher boiling points than alkane and alkene.
The molecule but-2-ene, CH3 CH, and but-1-ene, CH2 are constitu tional isomers.
rotation about a double bond is severely restricted because of the p bond The two molecule are different, because they can't be converted by twisting one end of the molecule.
The compounds have different physical properties because of their different structures.
Chapter 27 will examine elimination reactions in more detail.
An additional bond is formed between the C atoms when a small molecule is produced in an elimination reaction.
Ethane is the principal alkene of the chemical industry.
Its main use is in the manufacture of polymers, although it is also used to manufacture other organic chemicals.
In the commercial production of ethylene, reaction (26.4) is unimportant because of thermal cracking of other hydrocarbons.
In the presence of a very strong base, the amide anion removes the protons from acetylene to form ammonia and salt.
One of the most important organic raw materials in the chemical industry was acetylene.
The use of acetylene in the manufacture of other chemicals for the production of other chemicals for the production of other chemicals for the production of other chemicals for the production of other chemicals for the production of other chemicals for the production of other chemicals for the production of other chemicals for the production of In the next chapter, we will discuss the reactions of polymers.
In a variety of applications, Acetylene is used to produce high-temperature flames.
The basis of oxyacetylene torches used for cutting and welding metals is the burning of acetylene in excess oxygen.
Alkenes and alkynes are used to make other compounds.
Adding atoms to the carbon atoms on either side of a double or triple bond is a characteristic reaction.
One example of an addition reaction is when hydrogen atoms add across a carbon-carbon bond of an alkene to give an alkane.
The basis of simple qualitative tests that can be used to determine whether a compound is an alkene or an alkyne can be found in certain addition reactions.
The decolorization of bromine can be seen in a photo on the next page.
Highly substituted alkenes are not very helpful when bromine is not helpful.
The assignment of configuration is one of the compounds named.
To assign the configuration of the alkene, we need to assign the priorities to the substituents attached to each carbon in the double bond.
The chlorine atom has the highest priority since 2 carbon atoms are bonding to it.
Two carbons are bonding to an ethyl group.
The ethyl group's carbon can be canceled in each group.
The carbon has the highest priority.
The isopropyl group takes precedence.
The groups of the highest priority are on the same side of the double bond.
Two carbon atoms are bonding to two groups.
The fluorine has the highest priority because it is the carbon of the fluoromethyl group.
The fluoromethyl group takes precedence.
Two carbon atoms are bonding to an ethyl group and a chloroethyl group.
The chloroethyl group is the first point of difference on these substituent chains.
The groups of the highest priority are on opposite sides of the double bond.
It takes quite a bit of practice to master organic nomenclature and it is not the most exciting of topics.
It is an important part of organic chemistry.
The molecule benzene, C6H6, is the most aromatic hydrocarbons.
The bond ing in the benzene molecule was discussed in some detail.
The structures of the molecule were shown.
Two C and four H atoms are less than the starting atoms when rings are fused together.
The text uses an inscribed circle for the simple benzene ring and alternating single and double bonds for fused rings.
One of the possible resonance structures for the molecule is the bond arrangement.
The handling of aromatic hydrocarbons should always be done with care.
Red blood cells and white blood cells can be killed by a decreased production of both red blood cells and white blood cells.
Benzene is a carcinogen.
Benzene and other toxic aromatic compounds have been isolated in the tar formed by burning cigarettes, in polluted air, and as a decomposition product of grease in the charcoal grilling of meat.
A close examination of the structures of aromatic molecules shows that they all have the same features.
There are alternating single and double bonds in his representation of the theory.
The molecule is still being used.
The double bonds have p electron clouds associated with them.
Co., Sidney, Ohio has 14n + 22 electrons.
The benzene molecule has six electrons in the p electron clouds.
The molecule has a number of 14 and 22.
The anthracene molecule has a number of 14.
The two molecules depicted in the margin are not aromatic.
The 1,3,5 Hexa-1,3-5-triene molecule has six p electrons in its bonding system, but it is not a cyclic molecule.
The 1,3-cyclopentadiene molecule has only four p electrons in a bonding system that does not extend completely around the ring.
Benzene is insoluble in water butsoluble in organic solvents.
The boiling points of aromatic hydrocarbons are slightly higher than those of alkanes.
For example, hexane, C6H14, has a boiling point of 69 degC, whereas benzene has a boiling point of 80 degC.
The attractive forces between molecule can be explained by the delocalized electron charge density of benzene.
The phenyl and benzyl groups are important aromatic groups.
Two phenyl groups may bond together, as in biphenyl, or phenyl groups may be substituents in other molecule, as in phenylhydrazine, used in the detection of sugars.
The structures are shown in the margin.
We use a numbering system for the C atoms in the ring in order to name the substituted H atoms on the benzene molecule.
CH3 is on the benzene ring.
The carbon atoms in the ring are numbered so that the substituents appear at the lowest numbers possible, as shown below for 1-bromo-2-chlorobenzene.
The majority of the billions of pounds of benzene produced in the United States is derived from oil.
The process involves dehydrogenation.
The production of vinylbenzene is the most important use of benzene.
The manufacture of phenol, the synthesis of dodecylbenzene, and as an octane enhancer in gasoline are other applications.
The production of aromatic compounds by dehydrogenation yields large amounts of hydrogen gas, which is an important reactant in the synthesis of ammonia.
In the 19th century, compounds containing functional groups were described in this section.
We will not discuss the chemical transformations between some of them until the next chapter.
The benzene ring has a hydroxyl group attached to it.
The anion formed by a phenol is stable by resonance but the anion formed by an alcohol is not.
A diol and a polyol are used in automobile antifreeze solutions and as part of the body's mechanism for fat storage.
The physical properties of aliphatic alcohols are influenced by hydro Gen bonding.
The molecule becomes more like a gas.
Low-molecular mass alcohols tend to be water-soluble, whereas high-molecular mass alcohols are not.
Depending on the nature of the other substituents on the benzene ring, the boiling points and solubilities of the phenols vary.
Explain why the name Sec-pentyl alcohol does not identify a compound.
The hydration of alkenes and the hydrolysis of alkyl halides can be used to prepare alcohols.
One or more atoms add to a molecule.
An atom is replaced by another in a substitution reaction.
In Chapter 27 we will have a closer look at these types of reactions.
Methanol is the simplest alcohol.
It can cause death or blindness if eaten.
Carbon monoxide and hydrogen are used to make most methanol.
Methanol is the most extensively produced alcohol.
It is used in the synthesis of other organic chemicals and as a solvent, but it may be the most important use as a motor fuel.
Grain alcohol is found in alcoholic bever ages.
It can be produced from the juices of sugarcane or other materials that contain natural sugars.
The industrial method involves hydration of ethylene with a catalyst.
HOCH2CH2OH has a higher boiling point than water.
It's an excellent, permanent, nonvolatile antifreeze.
It is also used in the manufacture of plasticizers.
glycerin is a by-product in the manufacture of soap.
It is a sweet, syrupy liquid with water in all its forms.
glycerol can be used to keep skin moist and soft and is found in cosmetics.
A deprotonated form of the alcohol is called the alkoxide ion, or RO-.
The alkoxide ion is formed by the reaction of alcohol and metal.
A giant soap bubble is used to confirm whether a compound is an alcohol.
Reaction (26.11) is more air pocket enclosed in a thin commonly used to produce alkoxide ion that can be used in other reactions.
An alkoxide ion can react with a haloalkane if water evaporates, the film breaks and the bubble burst.
This reaction is an example of a substitution reaction.
The ether is formed by the soap-water mixture.
The strength of the ethers can be either pure aliphatic or aromatic.
The two substances have the same formula, but they have different physical and chemical properties.
They have different properties because they have different functional groups.
There are two constitutional isomers.
The system for naming ethers treats them as alkanes that have an alkoxy substituent.
The larger substituent defines the stem while the smaller substituent is considered part of the alkoxy group.
For ethylmethyl ether, the IUPAC name is methoxyethane, and for anisole, it is methoxybenzene.
There are ethers that can be cyclic.
A carbon atom in a cyclohexane molecule is shown in the margin.
The H atom has been replaced by an oxygen atom.
The margin has a picture of oxacyclohexane.
Diethyl ether can be prepared by eliminating a water molecule from between two alcohols with a strong dehydrating agent.
The molecule below should be unreactive.
In the presence of most oxidizing and reducing agents, butyl methyl has been and has been alkalis.
It is easy for chemists to administer and relax the muscles with the help of MTBE.
It's become somewhat annoying to the respiratory passages and causes nausea.
The name was used for this compound.
Because of its high toxicity in water, butyl ether is being phased out of use.
The odors of 1-Phenylethanone (acetone) (diethyl ketone) (acetophenone) are recognizable.
Some aldehydes and ketones can be used as flavoring agents.
The berry and mushroom flavors are caused by alpha-demascone and 2-octanone.
Butanedione is a yellow liquid with a cheese-like smell that gives butter its flavor.
The longest chain is the parent chain.
The carbon of the aldehyde group is the starting point for the numbering of the chain.
The aldehyde is readily converted to a carboxylic acid.
The partial oxidation can be done with the reagent pyri reaction in an organic solvent.
Ketones are more resistant to oxidation than alcohols and aldehydes.
Two H atoms are added to the double bond.
H atoms are not directly involved.
The attack of the carbonyl carbon atom by a hydride 1H-2 ion is the first step in the reaction.
aldehydes and ketones can be used as starting materials and reagents for the synthesis of other organic compounds.
The carbonyl group has a slightly positive carbon atom and is prone to attack by species that are attracted to centers of positive charge.
The simplest aldehyde is H2C " O", a gas that can be easily dissolved in water.
Billions of kilograms of formaldehyde are used in the manufacture of synthetic resins each year.
Paraformaldehyde is an antiseptic and an insecticidal substance.
The most important of the ketones is acetone.
It is a very volatile liquid and very dangerous.
A good solvent for a variety of organic compounds is acetone.
acetone is miscible with water in all proportions.
The general formula is RCOOH.
The acid is called a dicarboxylic acid if there are two carboxyl groups on the molecule.
The benzene ring has a carboxyl group attached to it.
Straight- or branched-chain acids can be named either by their IUPAC names or by using Greek letters in conjunction.
The derivatives of benzoic acid are called aromatic acids.
COOH is a group.
There are carboxylic acids in nature.
The formulas for these acids are shown in the margin.
The smell of oxalic acid is characteristic.
The smell of human sweat is caused by O.
Draw the structure of the acid.
carboxylic acids have high melting and boiling points because of hydrogen bonding.
When carboxylic acids are dissolved in water, they act as weak acids.
A simple way to determine if a compound is a carboxylic acid is to add it to a solution of either NaHCO31aq2 or Na2CO31aq2.
The bubbles of CO21g2 will be visible if the compound is acid.
The preparation and uses of carboxylic acids can be obtained in the laboratory by oxidation of a primary alcohol or aldehyde.
The oxidizer is usually KMnO41aq2 in an alkaline medium.
The free carboxylic acid can be regenerated if the medium is acidic.
Primary alcohols and aldehydes can be converted to carboxylic acids.
The hydrolysis of nitriles can be used to make carboxylic acids.
RCOO- is produced if the reaction is carried out in basic solution.
The solution must be acidified to get RCOOH.
We will look at some of the reactions that are used in organic chemistry in Chapter 27.
The IUPAC names for these acyl groups are rarely used.
The structure of aspirin is shown in the margin.
The general formula of an ester is RCOOR?.
The reaction of a carboxylic acid and an alcohol can be done in the lab.
There are two products of the reaction.
An excess of alcohol is used to ensure a high yield of the ester.
There are two parts to the distinctive aroma and Esters.
The combination is based on ethanoic acid.
There are more examples here.
The pleasant odors of the carboxylic acids from which they are derived are different.
The characteristic fragrances of flowers and fruits can be traced to the esters they contain.
They are used in perfumes and in the manufacture of flavoring agents.
esters are insoluble in water.
Their melting points and boiling points are not as high as those of alcohols and acids.
There is no hydrogen bonding in the esters.
A substitute amide can be obtained if hydrogen atoms on the nitrogen atom are replaced with other groups.
The NH2 group of ethanamide has been replaced by other groups.
There are a few examples.
The resonance structures shown below are promoted by the carbonyl group.
The nitrogen atom has only one pair of electrons and they are delocalized over the carbonyl group.
The carbonyl group is most likely to be protonated in acidic conditions.
The first step in reactions of esters and amides under acidic conditions is the protonsation of the oxygen in a carbonyl group.
One way to make an amide is to treat a carboxylic acid with ammonia and form an Ammonia Salt.
The pathway for making ethanamide is summarized in the following sequence.