Introduction to organic chemistry. Organic compounds “ Organic ” originally referred to any...

transcript

Introduction to organic Introduction to organic chemistrychemistry

Organic compoundsOrganic compounds

“Organic” originally referred to any chemicals that came from Organisms

Organic chemistry is the study of the Organic chemistry is the study of the compounds of carboncompounds of carbon

Carbon atoms are unique because Carbon atoms are unique because they form strong covalent bonds with they form strong covalent bonds with each othereach other

Composition of organic compounds: Composition of organic compounds: C,H,N,O,halogens (Cl,Br)C,H,N,O,halogens (Cl,Br)

A. A. Carbon BondingCarbon Bonding

When carbon has 4 atoms bound to it When carbon has 4 atoms bound to it these atoms have a tetrahedral these atoms have a tetrahedral shape. shape.

• An organic molecule (hydrocarbon) is formed when carbon bonds to hydrogen. The simplest hydrocarbon consists of 4 hydrogen atoms bonded to a carbon atom (called methane)

In addition to binding to hydrogen, carbon can also bind to other carbon atoms, as illustrated below:

Hydrocarbons Hydrogen + Carbon

In fact the uniqueness of carbon comes from the fact that it can bind to itself. Carbon atoms can form long chains:

branched chains :

in fact, there appears to be almost no limit to the number of different structures that carbon can form. To add to the complexity of organic chemistry, neighboring carbon atoms can form double and triple bonds in addition to single carbon-carbon bonds

A carbon-carbon single bond

A carbon-carbon double bond

A carbon-carbon triple bond

Saturated hydrocarbonsSaturated hydrocarbons• Have the maximum number of Have the maximum number of

hydrogen atoms attached to hydrogen atoms attached to each carbon atom.each carbon atom.

• Are alkanes and cycloalkanes Are alkanes and cycloalkanes with single C-C bonds. with single C-C bonds.

CHCH33——CHCH22——CHCH33

Saturated HydrocarbonsSaturated Hydrocarbons

Unsaturated Unsaturated hydrocarbonshydrocarbons

• Have fewer Have fewer hydrogen atoms hydrogen atoms attached to the attached to the carbon chain than carbon chain than alkanes.alkanes.

• Are alkenes with Are alkenes with double bonds.double bonds.

• Are alkynes with Are alkynes with triple bonds. triple bonds.

Unsaturated HydrocarbonsUnsaturated Hydrocarbons

FormulasFormulas Molecular formulas just tell you what kinds of Molecular formulas just tell you what kinds of

atoms are in the molecule, but they donatoms are in the molecule, but they don ’’t tell t tell you how they are attachedyou how they are attached

structural formulas show you the attachment structural formulas show you the attachment pattern in the moleculepattern in the molecule

In expanded structural formulas, all the In expanded structural formulas, all the individual bonds are drawn.individual bonds are drawn.

In condensed structural formulas, each In condensed structural formulas, each carbon is written with the H atoms carbon is written with the H atoms connected to it.connected to it.

models not only show you the attachment models not only show you the attachment pattern, but give you an idea about the pattern, but give you an idea about the shape of the moleculeshape of the molecule

Line-Angle FormulasLine-Angle Formulas

Each angle, and beginning and end Each angle, and beginning and end represent a C atom represent a C atom

H omitted on CH omitted on C– included on functional groups included on functional groups – double line is double bond, triple line is triple double line is double bond, triple line is triple

bondbond Multiple bonds indicatedMultiple bonds indicated

FormulasFormulas

C2H6 CH3CH3 C

C3H8 CH3CH2CH3 C

C4H10 CH3CH2CH2CH3 C

C4H10 C(CH3)2 C

C1 – C5C1 – C5::AAre Gasesre Gasesat Room Temperatureat Room Temperature

C15C15::

AAre Solidre Solidss

at Room Temperatureat Room Temperature

C6 - C15C6 - C15::

AAre Liquidsre Liquids

at Room Temperatureat Room Temperature

Types of Carbon AtomsTypes of Carbon Atoms

Primary carbon (1Primary carbon (1oo))– a carbon bonded to a carbon bonded to

one other carbonone other carbon

Secondary carbon (2Secondary carbon (2oo))– a carbon bonded to a carbon bonded to

two other carbonstwo other carbons

Tertiary carbon (3Tertiary carbon (3oo))– a carbon bonded to a carbon bonded to

three other carbonsthree other carbons

Functional GroupsFunctional Groups other organic compounds are hydrocarbons in other organic compounds are hydrocarbons in

which which functional groupsfunctional groups have been substituted have been substituted for hydrogensfor hydrogens

a functional group is a group of atoms that show a functional group is a group of atoms that show a characteristic influence on the properties of the a characteristic influence on the properties of the moleculemolecule– generally, the reactions that a compound will perform generally, the reactions that a compound will perform

are determined by what functional groups it hasare determined by what functional groups it has– since the kind of hydrocarbon chain is irrelevant to the since the kind of hydrocarbon chain is irrelevant to the

reactions, it may be indicated by the general symbol reactions, it may be indicated by the general symbol RR

CH3—OHR group functional group

An alcohol contains the hydroxyl (-OH) functional group.In an ether, an oxygen atom is bonded to two carbon atoms.

–C–O–C– .

In amines, the functional group is a nitrogen atom. |

—N —

Carboxylic acids contain the carboxyl group, which is a carbonyl group attached to a hydroxyl group.

— C—OHAn ester contains the carboxyl group between carbon atoms.

An aldehyde contains a carbonyl group (C=O), which is a carbon atom with a double bond to an oxygen atom.

In a ketone, the carbon of the carbonyl group is attached to two other carbon atoms.

AlkanesAlkanes paraffinsparaffins aliphaticaliphatic general formula Cgeneral formula CnnHH2n+22n+2 for chains for chains Straight-Chain Alkanes Combined with the -ane ending is

a prefix for the number of carbons very unreactivevery unreactive come in chains or/and ringscome in chains or/and rings

– CHCH33 groups at ends of chains, CH groups at ends of chains, CH22 groups in the middle groups in the middle

– chains may be straight or branchedchains may be straight or branched saturatedsaturated branched or unbranchedbranched or unbranched

Naming AlkanesNaming Alkanes

The name for an alkane is based on The name for an alkane is based on Greek root with the suffix Greek root with the suffix ––ane.ane.

AlkAlkaneanes s –– saturated hydrocarbons saturated hydrocarbons(C(CnnHH2n+22n+2))

methane ethane hexane

3-methylpenthane

! Alkanes are not planar !

N a m e L e w i sS t r u c t u r e

F o r m u l a B o i l i n gP o i n t

M e t h a n eC H

HC H 4 - 1 6 2 ° C

E t h a n eC

C H 3 C H 3 - 8 9 ° C

P r o p a n eCH

HC H 3 C H 2 C H 3 - 4 2 ° C

B u t a n eCH

HC H 3 C H 2 C H 2 C H 3 0 ° C

P e n t a n eCH

HC H 3 C H 2 C H 2 C H 2 C H 3 3 6 ° C

H e x a n eCH

HC H 3 C H 2 C H 2 C H 2 C H 2 C H 3 6 9 ° C

Alkyl GroupsAlkyl Groups

An alkyl groupAn alkyl group is composed of one or more carbon is composed of one or more carbon

atoms attached to a carbon chainatoms attached to a carbon chain Is derived from the corresponding Is derived from the corresponding

alkane by removing one hydrogenalkane by removing one hydrogen Is named by replacing the Is named by replacing the ––ane ending ane ending

of the corresponding alkane with of the corresponding alkane with ––ylyl Derived from methane is methyl and Derived from methane is methyl and

from ethane is ethylfrom ethane is ethyl

Alkyl GroupsAlkyl GroupsC

CH3-, METHYL

CH3CH2-, ETHYL

CH3CH2CH2-, PROPYL

(CH3)2CH-, ISOPROPYL

NamingNaming Each name consists of 3 partsEach name consists of 3 parts

prefix prefix indicates position, number, and type of branches indicates position, number, and type of branches indicates position, number, and type of each functional groupindicates position, number, and type of each functional group

parentparent indicates the length of the longest carbon chain or ringindicates the length of the longest carbon chain or ring

suffixsuffix indicates the type of hydrocarbonindicates the type of hydrocarbon

– ane, ene, yneane, ene, yne certain functional groupscertain functional groups

Prefix- Parent- SuffixPrefix- Parent- Suffixwhere are the substituents How many carbons What family?where are the substituents How many carbons What family?

Summary: IUPAC (International Union Summary: IUPAC (International Union of Pure and Applied Chemistry) Rules of Pure and Applied Chemistry) Rules

for Alkane Nomenclaturefor Alkane Nomenclature 1.1. Find and name the longest continuous carbon Find and name the longest continuous carbon

chain. This is called the chain. This is called the parent chainparent chain. (Examples: . (Examples: methane, propane, etc.)methane, propane, etc.)

2.2. Number the chain consecutively, starting at the Number the chain consecutively, starting at the end nearest an attached group (end nearest an attached group (substituentsubstituent). ).

3.3. Identify and name groups attached to this chain. Identify and name groups attached to this chain. (Examples: methyl-, bromo-, etc.)(Examples: methyl-, bromo-, etc.)

4.4. Designate the location of each substituent group Designate the location of each substituent group with the number of the carbon parent chain on with the number of the carbon parent chain on which the group is attached. Place a dash between which the group is attached. Place a dash between numbers and letters. (Example: 3-chloropentane)numbers and letters. (Example: 3-chloropentane)

5.5. Assemble the name, listing groups in alphabetical Assemble the name, listing groups in alphabetical order. order. The prefixes di, tri, tetra etc., used to designate The prefixes di, tri, tetra etc., used to designate several groups of the same kind, are not considered several groups of the same kind, are not considered when alphabetizing. Place a comma between when alphabetizing. Place a comma between multiple numbers. (Example: 2,3-dichloropropane)multiple numbers. (Example: 2,3-dichloropropane)

Example Example –– Name the alkaneName the alkane

1)1) find the longest continuous C chain find the longest continuous C chain and use it to determine the base and use it to determine the base name name

CH3CHCH2CHCH3

CH3 CH3

CH3CHCH2CHCH3

CH3 CH3

since the longest chain has 5 Cthe base name is pentane

Prefixes for # of CarbonsPrefixes for # of Carbons

11MethMeth66HexHex

22EthEth77HeptHept

33PropProp88OctOct

44ButBut99NonNon

55PentPent1010DecDec

EndingsEndings

Alkanes (all C-C single bonded parent Alkanes (all C-C single bonded parent chain) end in chain) end in ––aneane– MethMethaneane CHCH44

– EthEthaneane CC22HH66

– PropPropaneane CC33HH88

Attached carbon groups Attached carbon groups (substituents) end in (substituents) end in ––ylyl– MethMethylyl CH CH33 - -– EthEthylyl CHCH33CHCH22--– PropPropylyl CHCH33CHCH22CHCH2 2 –– 3-ethylpentane

Step 2. Number the parent Step 2. Number the parent chainchain..

Number the parent chain so that the Number the parent chain so that the attached groups are on the lowest attached groups are on the lowest numbersnumbers

1 2 3 4 5

Methyl is on carbon #2 of the parent chain

5 4 3 2 1

Methyl is on carbon #4 of the parent chain

GREEN is the right way for this one!

Groups on 2, 3, and 5

Groups on 4, 6, and 7

1 2 3 4 5 6

Groups on 2 and 5

7 6 5 4 3 2 1

Groups on 3 and 6

Step 3. Name the attached Step 3. Name the attached groupsgroups..

Carbon (alkCarbon (alkylyl) groups) groups– MethMethylyl CH CH33 - -– EthEthylyl CHCH33CHCH22--– PropPropylyl CHCH33CHCH22CHCH2 2 ––

HalogensHalogens– Fluoro (F-)Fluoro (F-)– Chloro (Cl-)Chloro (Cl-)– Bromo (Br-)Bromo (Br-)– Iodo (I-)Iodo (I-)

Step 4. Designate where the Step 4. Designate where the group is attached to the parent group is attached to the parent

chainchain.. Use the numbers of the parent chain Use the numbers of the parent chain

from step 2 to designate the location from step 2 to designate the location of the attached groups to the parent of the attached groups to the parent chain.chain.

1 2 3 4 5

2-methyl

Step 5. Alphabetize the groups, Step 5. Alphabetize the groups, combine like groups, and combine like groups, and

assembleassemble.. The prefixes di, tri, The prefixes di, tri,

tetra etc., used to tetra etc., used to designate several designate several groups of the same groups of the same kindkind

Prefixes are not Prefixes are not considered when considered when alphabetizing alphabetizing (Example: dimethyl = (Example: dimethyl = m for alphabetizing)m for alphabetizing)

Parent chain goes LASTParent chain goes LAST

1,1,1-trichloro-1-fluoromethane

1,1-dichloro-1,1-difluoromethane

Practice Practice –– Name the Following Name the Following

CH3CHCHCH2CH3

CH2CH3

3-ethyl-2-methylpentane

CHCH33

CHCH22 CH CH

CHCH33 CH CH CH CH33

CHCH3 3

2,3-dimethylpentane2,3-dimethylpentane

5-ethyl-3,4-dimethyloctane 5-ethyl-3,4-dimethyloctane

AlkenesAlkenes also known as olefinsalso known as olefins aliphatic, unsaturatedaliphatic, unsaturated

– C=C double bondsC=C double bonds formula for one double bond = Cformula for one double bond = CnnHH2n2n

– subtract 2 H from alkane for each double subtract 2 H from alkane for each double bondbond

trigonal shape around Ctrigonal shape around C– flatflat

much more reactive than alkanesmuch more reactive than alkanes polyunsaturated = many double bondspolyunsaturated = many double bonds

AlkynesAlkynes also known as acetylenesalso known as acetylenes aliphatic, unsaturatedaliphatic, unsaturated CCººC triple bondC triple bond formula for one triple bond = Cformula for one triple bond = CnnHH2n-2n-

– subtract 4 H from alkane for each subtract 4 H from alkane for each triple bondtriple bond

linear shapelinear shape more reactive than alkenesmore reactive than alkenes

Naming Alkenes and Naming Alkenes and AlkynesAlkynes

change suffix on main name from change suffix on main name from --aneane to - to -eneene for base name of alkene, for base name of alkene, or to or to --yneyne for the base name of the for the base name of the alkynealkyne

number chain from end closest to number chain from end closest to multiple bondmultiple bond

number in front of main name number in front of main name indicates first carbon of multiple bondindicates first carbon of multiple bond

Name the AlkeneName the Alkene1)1) find the longest, continuous C chain find the longest, continuous C chain

that contains the double bond and use that contains the double bond and use it to determine the base name it to determine the base name

since the longest chain with the double bond has 6 Cthe base name is hexene

H3C CH C

H2C CH3

CH CH3

H2C CH3

Name the AlkeneName the Alkene

2)2) identify the substituent branches identify the substituent branches

there are 2 substituentsone is a 1 C chain, called methyl

the other one is a 2 C chain, called ethyl

H3C CH C

H2C CH3

CH CH3

H2C CH3

H3C CH C

H2C CH3

CH CH3

H2C CH3

Name the AlkeneName the Alkene3)3) number the chain from the end closest number the chain from the end closest

to the double bondto the double bondthen assign numbers to each substituent based on the number of the main chain C it’s attached to

Name the AlkeneName the Alkene4)4) write the name in the following orderwrite the name in the following order

1)1) substituent number of first alphabetical substituent substituent number of first alphabetical substituent –– substituent name of first alphabetical substituent substituent name of first alphabetical substituent ––

use prefixes to indicate multiple identical substituentsuse prefixes to indicate multiple identical substituents2)2) repeat for other substituentsrepeat for other substituents3)3) number of first C in double bond number of first C in double bond –– name of main chainname of main chain

3–ethyl– 4–methyl–2–hexene

H3C CH C

H2C CH3

CH CH3

H2C CH3

H3C C C

CH2 CH3

H2C CH3

H3C C C

CH2 CH3

H2C CH3

3,4-dimethyl-3-hexene

3 4 5 6

Name the AlkyneName the Alkyne1)1) find the longest, continuous C chain find the longest, continuous C chain

that contains the triple bond and use it that contains the triple bond and use it to determine the base name to determine the base name

since the longest chain with the triple bond has 7 Cthe base name is heptyne

CH3 CH2 CCH CH

CH3 CH3HC

Name the AlkyneName the Alkyne

2)2) identify the substituent branches identify the substituent branches

there are 2 substituentsone is a 1 C chain, called methylthe other one is called isopropyl

CH3 CH2 CCH CH

CH3 CH3HC

CH2 CCH CH

CH3 CH3HC

C CH3CH3

Name the AlkyneName the Alkyne3)3) number the chain from the end closest number the chain from the end closest

to the triple bondto the triple bondthen assign numbers to each substituent based on the number of the main chain C it’s attached to

1234567

Name the AlkyneName the Alkyne4)4) write the name in the following orderwrite the name in the following order

1)1) substituent number of first alphabetical substituent substituent number of first alphabetical substituent –– substituent name of first alphabetical substituent substituent name of first alphabetical substituent –– use prefixes to indicate multiple identical use prefixes to indicate multiple identical

substituentssubstituents2)2) repeat for other substituentsrepeat for other substituents3)3) number of first C in double bond number of first C in double bond –– name of main chainname of main chain

4–isopropyl–6–methyl–2–heptyne

CH2 CCH CH

CH3 CH3HC

C CH3CH3

1234567

CH2CH3

3,3-dimethyl-1-pentyne

IUPAC Rules for Naming HydrocarbonsIUPAC Rules for Naming Hydrocarbons

1.1. Choose the correct endingChoose the correct ending: -ane, -ene, or -yne: -ane, -ene, or -yne2.2. Determine the longest carbon chainDetermine the longest carbon chain. Where a double or triple . Where a double or triple

bond is present, choose the longest chain that includes this bond is present, choose the longest chain that includes this bond. If there is a cyclic structure present, the longest chain bond. If there is a cyclic structure present, the longest chain starts and stops within the cyclic structure.starts and stops within the cyclic structure.

3.3. Assign numbers to each C of the parent chainAssign numbers to each C of the parent chain. For alkenes . For alkenes and alkynes the first carbon of the multiple bond should have and alkynes the first carbon of the multiple bond should have the smallest number. For alkanes the first branch (or first the smallest number. For alkanes the first branch (or first point of difference) should have the lowest #. Carbons in a point of difference) should have the lowest #. Carbons in a multiple bond must be numbered consecutively.multiple bond must be numbered consecutively.

4.4. Attach a prefixAttach a prefix that corresponds to the number of carbons in that corresponds to the number of carbons in the parent chain. the parent chain. Add cyclo-Add cyclo- to the prefix if it is a cyclic to the prefix if it is a cyclic structure.structure.

5.5. Determine the correct name for each branchDetermine the correct name for each branch (“alkyl” groups (“alkyl” groups include methyl, ethyl, propyl, etc.)include methyl, ethyl, propyl, etc.)

6.6. Attach the name of the branches alphabeticallyAttach the name of the branches alphabetically, along with , along with their carbon position, to the front of the parent chain name. their carbon position, to the front of the parent chain name. Separate numbers from letters with hyphens (e.g. 4-ethyl-2-Separate numbers from letters with hyphens (e.g. 4-ethyl-2-methyldecane)methyldecane)

7.7. When two or more branches are identical, use prefixes (di-, When two or more branches are identical, use prefixes (di-, tri-, etc.)tri-, etc.) (e.g. 2,4-dimethylhexane). Numbers are separated (e.g. 2,4-dimethylhexane). Numbers are separated with commas. Prefixes are ignored when determining with commas. Prefixes are ignored when determining alphabetical order. (e.g. 2,3,5-trimethyl-4-propylheptane)alphabetical order. (e.g. 2,3,5-trimethyl-4-propylheptane)

8.8. When identical groups are on the same carbon, repeat the When identical groups are on the same carbon, repeat the number of this carbon in the namenumber of this carbon in the name. (e.g. 2,2-dimethylhexane). (e.g. 2,2-dimethylhexane)

IUPAC Rules for Naming HydrocarbonsIUPAC Rules for Naming Hydrocarbons

Naming Side ChainsExample: use the rules on this handout to

name the following structure

CH3 CH2 C

Rule 1: choose the correct ending

Rule 2: determine the longest carbon chain

CH3 CH2 C

Naming Side Chains

Rule 3: Assign numbers to each carbon

CH3 CH2 C

Naming Side Chains

Rule 3: Assign numbers to each carbon

CH3 CH2 C2

CH3 CH2 C

Naming Side Chains

1-hexene ene

Rule 4: attach prefix (according to # of Cs)

Naming Side Chains

CH3 CH2 C2

CH3 CH2 C

CH3 CH2 C2

Rule 5: Determine name for side chains

CH3 CH2 C

1-hexene 1-hexene

methyl

Naming Side Chains

CH3 CH2 C

CH3 CH2 C2

1-hexene 2-ethyl-4-methyl-4-methyl-1-hexene

methyl

methylRule 6: attach name of branches alphabetically

Naming Side Chains

Rule 7,8: group similar branches

CH3 CH2 C

CH3 CH2 C2

1-hexene 2-ethyl-4-methyl-4-methyl-1-hexene

methyl

Naming Side Chains

Rule 7,8: group similar branchesRule 7,8: group similar branches

CH3 CH2 C

CH3 CH2 C2

22--ethyl-4,4-dimethyl-1-hexeneethyl-4,4-dimethyl-1-hexene

methyl

Naming Side ChainsNaming Side Chains

22--butenebutene

propenepropene

11--butynebutyne

CH3 CH CH2

CH3 CH CH CH3

CH3 CH CH C

CH3 CH3

2,42,4--dimethyl-2-pentenedimethyl-2-pentene

CH C CH2 CH3

b) sameb) same

c) 5-ethyl-4-methyl-2-heptynec) 5-ethyl-4-methyl-2-heptyne

a) 3,3-dimethyl-1-pentenea) 3,3-dimethyl-1-pentene

CH2 CH C CH2 CH3

CH3 C CH CH2

CH2 CH3

CH CH CH2

CH2 CH3

CH3CH3

For more lessons, visit www.chalkbored.com

Introduction to organic chemistry. Organic compounds “ Organic ” originally referred to any...

Documents