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Chem 1152: Exam 2 Review
Naming Compounds
Naming alkanes – Rules Rules for naming alkanes have been standardized by IUPAC (International Union of Pure and Applied Chemistry) Prefix-------------------------------------------- Parent--------------------------------- Suffix Substituents Longest C Chain Family (Functional class) (# and ID of attached groups) How to name an alkane 1. Find the longest continuous C chain. This is the Parent.
If 2 different chains of equal length are present, the parent is the one with the MOST branch points.
2. Number the atoms in the parent chain. Begin numbering at the end nearest the 1st branch point. If 1st point is the same at either end, begin at end nearest the 2nd, 3rd branch points. We want to label this so that branch points are the lowest numbers possible.
3. Identify and number the substituents. Assign a number to each substituent based on carbon number in parent chain. Two substituents on the same carbon (not 3) get the same number. If both substituents are the same, use the prefix di-. If structure has multiple identical substituents, put them altogether in the name. For
example: 2,3,4,5,6-pentamethyloctane. 4. Write name as a single word.
Separate prefixes with hyphens. Use commas (no spaces) to separate numbers. If 2 or more different substituents are present, cite in alphabetical order. Multiplier prefixes (di-, tri-, tetra-, penta-, etc.) are NOT used for alphabetizing. The prefixes sec- and t- are NOT used for alphabetizing, but iso- IS used for
alphabetizing.
Rules for naming cycloalkanes 1. Substituents are named so that the first one is determined alphabetically. 2. After the first one is identified, the others are numbered to get the lowest possible
sequence of numbers.
Cl
CH3
1
2
Cl
CH3
CH3
1
23
chloro-3-methylcyclopentane chloro-2,3-dimethylcyclopentane
Naming Alkenes
1. Name the longest chain that contains the double bond or double bonds. The name of the chain will end in –ene.
2. Number this longest chain so the C=C bond or bonds has/have the lowest number.
3. The first C of the C=C bond (for C=C bond to have lowest number) identifies the positional location of the double bond.
4. Name the attached functional groups. 5. Combine the names of the attached groups and longest chain, the same as
you would with alkanes.
Naming Alkynes
1. Name of cmpd ends in yne. 2. The longest chain chosen for the root name must include both carbon
atoms of the triple bond. 3. The root chain must be numbered from the end nearest a triple bond
carbon atom. a. If the triple bond is in the center of the chain, the nearest substituent
rule is used to determine the end where numbering starts. 4. The smaller of the two numbers designating the carbon atoms of the triple
bond is used as the triple bond locator. 5. If several multiple bonds are present, each must be assigned a locator
number. Double bonds precede triple bonds in the IUPAC name, but the chain is numbered from the end nearest a multiple bond, regardless of its nature. The name will then have multiplier prefix (e.g., diyne, triyne, etc.)
6. Because the triple bond is linear, it can only be accommodated in rings larger than ten carbons. In simple cycloalkynes the triple bond carbons are assigned ring locations #1 and #2. Which of the two is #1 may be determined by the nearest substituent rule.
7. Substituent groups containing triple bonds are: HC≡C– Ethynyl group HC≡CH–CH2– Propargyl group
Rules for naming alcoholsRules for naming alcohols
For single hydroxy (-OH) group•Step 1: Identify longest chain that includes (-OH) group. Drop –e from hydrocarbon name, and replace with ending –ol.•Step 2: Number this parent chain to give lowest number to carbon with attached (-OH) group.•Step 3: Locate position of (-OH) group.•Step 4: Locate and name all branches attached to parent chain.•Step 5: Include names of all branches (still in alphabetical order) in prefix of compound name. Include location of (-OH) group.•Note: Multiple (-OH) groups are named by addiing diol, triol, etc, to end of alkane without removing -e.
CH3
CH3
OH1
253
4
2-ethyl-1-pentanol
OHOH
CH3
12 3
4
2-methyl-1,4-butanediol
Naming AlcoholsNaming Alcohols
CH3
CH3
CH3
CH3
OHCH3
2,2,4-trimethyl-3-hexanol
OH
CH3
CH3 OH
CH3
3-butyl-2,4-hexanediol
OH
OH
1,2-cyclohexanediol
CH3 CH3
CH3
OH
3-methyl-3-pentanol
OH
Br
CH3
5-bromo-3-ethyl-1-pentanol
CH3CH3
CH3
OH
2-isopropyl-1-methylcyclopropanol
OH
CH3CH3
2,2-dimethylcyclopentanol
OH
OHOH
CH3
1,2,4-hexanetriol
OH
3-phenyl-1-propanol
EthersEthers• Ether: Oxygen with carbon attached on either side.• Naming ethers• Common Names
1. Name the two groups attached to the oxygen then add the word ether2. If both groups the same, can be named with prefix di-.
• IUPAC Names– O-R group is alkoxy.– The –yl ending of smaller R group is replaced by –oxy.
CH3
O CH3
CH3 OCH3
CH3
OCH3
butyl methyl ether
ethyl propyl ether
dipropyl ether
CH3
CH3 OCH3
isopropyl propyl ether 1-methoxybutane
1-ethoxypropane
1-propoxypropane
1-isopropoxypropaneCl
CH3
CH3 OCH3
2-chloro-1-isopropoxypropane
OCH3
CH3
p-methoxytoluene
CH3
CH3
CH3 O
CH3
CH3
2-methoxy-3,4-dimethylhexane
ThiolsThiols• Thiols: Sulfur analogs of alcohols (-SH instead of –OH)• Chemically- similar (i.e., form similar compounds)• More volatile (lower BP) than alcohols but less water-soluble• Thiols stink!
– This is how skunks defend themselves– Chopped onions emit propanethiol– Thiols found in garlic– Ethanethiol added to natural gas (methane) so you can smell a leak
• IUPAC Names for simple thiols– The –SH group is a sulfhydryl group.– Follow the same steps for naming as you do for alcohols, but do not modify alkane
ending; instead add –thiol to end of parent.
SH
CH3
SH
CH3CH3
SH
CH3
CH3
CH3
butanethiol 2-butanethiol 2-methyl-3-hexanethiol
Naming AldehydesNaming Aldehydes
O
HCH3
pentanal
Cl
O
H
5-chloropentanal
CH3
O
H
Cl
5-chloro-4-ethylpentanal
H O
CH3CH3
2-ethylbutanal
CH3
O
H
CH3
CH3
3,4-dimethylhexanal
Cl
CH3 O
H
5-chloro-2-methylbenzaldehydeCl
O
H
m-chloro-benzaldehyde
CH3
O
CH3 O
H
5-methoxy-2-methylbenzaldehyde
Naming KetonesNaming Ketones
2-pentanone 5-chloro-2-pentanone 1-chloro-3-pentanone
4-ethylcyclohexanone 2-fluoro-5-methyl-4-hexanone
O
CH3 CH3
Ketone: Carbonyl group with two C attached.•Named by replacing –e with –one (IUPAC).•Numbered from end closest to carbonyl group
ClO
CH3
O
Cl
CH3
O
CH3CH3
F O
CH3
CH3
Chem 1152: Exam 2 Review
Reactions
Addition reactions to alkenesAddition reactions to alkenes
Halogenation: Addition of a Halide (fluorine, chlorine, bromine, iodine)
CH2CH3CH2CH Br-Br
Br
+ CH2CH3CH2CH
Br1-butene 1,2-dibromobutane
Hydrogenation: Use of metal catalyst (Pt, Pd, Ni) to add H
CHCH3CH3CH
H
+
H2-butene butane
H2 CHCH3CH3CH
Addition reactions to alkenesAddition reactions to alkenesAcid Rxn: (HCl, HBr, etc.)
CHCH3CH2
Br+
HHBr
CHCH3CH2
H Br
CHCH3CH2
1-bromopropane
2-bromopropane
The major product of this rxn is 2-bromopropane, not 1-bromopropane. This is due to: Markovnikov’s rule: When H-X reacts with alkene, H goes to C that already has the most H.
Hydration: Water may react with alkene in presence of acid catalyst
CH2CH3CH + H-OHOH H
H2SO4 CH2CH3CH
Alcohol ReactionsAlcohol Reactions
1. Alcohol Dehydration (Elimination Rxn):
H-OHH2SO4
R
OH
RR
HR 180 C
+
R
RR
R
• Alcohol Hydration (Addition Rxn)R
RR
R
H-OH+H2SO4
R
OH
RR
HR
Alcohol Dehydration to produce alkeneAlcohol Dehydration to produce alkene• Alcohol Dehydration (Elimination Rxn):
OH
CC
CC
H
HH
HH
HH
HH
H2SO4
180 oC
CC
C
CH
HH
H
H
H
HH
CC
CC
H
HH
HH
H
H
H
H-OH+
H-OH+
2-butene
1-butene
This rxn (at 180 °C) generates 2 products: 2-butene and 1-butene. The major product is 2-butene (90%) because both C=C bond carbons are
attached to at least one other carbon. The minor product is 1-butene (10%) because only one of the C=C bond
carbons is attached to at least one other carbon. The major product in these rxns will always be the one resulting in the
highest number of carbon groups bonded to the C=C carbons.
Alcohol Dehydration to produce etherAlcohol Dehydration to produce ether• Alcohol Dehydration (Elimination Rxn):
This rxn (at 140 °C) generates an ether and water. This rxn works mainly with primary alcohols.
H2SO4
140 oCR
OH H
R
O+ R
R
O
H
OH+
etheralcohol alcohol
Primary (1°)R O
H H
H
OH
H HH
Hydroxy bearing C is attached to either 0 or 1 other C
H2SO4
140 oCOHCH3 +
H
OH+CH3H
O OCH3
CH3
H2SO4
140 oCOHCH3
H
OH+CH3OCH3
H-OH+RC
O
HH
H
(O)+ R C
O
H
(O)R C
O
OH
Alcohol Oxidation for Primary AlcoholAlcohol Oxidation for Primary Alcohol
Carboxylic acid
Primary alcoholaldehyde
Immediate product of oxidation of primary alcohol is aldehyde, which is then readily further oxidized to a carboxylic acid.
The aldehyde product may be isolated before further oxidation by maintaining high temp. and boiling aldehyde out of rxn mixture.
This is possible because aldehydes do not H-bond like alcohols and carboxylic acids.
H-OH+RC
O
HR
H
(O)+ R C
O
R
Alcohol Oxidation for Secondary and Tertiary AlcoholsAlcohol Oxidation for Secondary and Tertiary Alcohols
Secondary alcohol ketone
Product of oxidation of secondary alcohol is a ketone, which resists further oxidation.
NO RXNR
CO
RR
H
(O)+
Tertiary alcohol
Multistep RxnsMultistep Rxns The synthesis of most alcohols may require multiple steps (i.e., to get
product X from reactant A, a product (B, C …X) must be created). To solve these problems, work backwards from the final product.
O
OOH (O)+ H-OH+
Oxidize 2° alcohol to form ketone.
+ OHH-OHH2SO4
Use acid-catalyzed hydration (addition) to form alcohol.
+ OHH-OHH2SO4
(O)+ O H-OH+
The completed series of rxns.
Hydrogenation Rxn – AldehydesHydrogenation Rxn – AldehydesAldehyde hydrogenation rxnAldehyde hydrogenation rxn
Alcohol oxidation rxnAlcohol oxidation rxn
H-OH+RC
O
HH
H
(O)+ R C
O
H
(O)R C
O
OH
Carboxylic acid
Primary alcoholaldehyde
Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7th Edition, 2011
Hydrogenation Rxns – KetonesHydrogenation Rxns – KetonesKetone hydrogenation rxnKetone hydrogenation rxn
H-OH+RC
O
HR
H
(O)+ R C
O
R
Secondary alcohol ketone
Alcohol oxidation rxnAlcohol oxidation rxn
Seager SL, Slabaugh MR, Chemistry for Today: General, Organic and Biochemistry, 7th Edition, 2011
Addition of alcohol to aldehydes and ketonesAddition of alcohol to aldehydes and ketones
Hemiacetal is unstable, hard to isolate. With excess alcohol and an acid catalyst, a stable acetal is formed.
Note the bidirectional arrows
O
R H
+ H
R
O
RO
HO
R H
H+, RO-H
RO
RO
R H + H-O-H
Hemiacetal Hemiacetal intermediateintermediate
acetalacetal
O
R R
+ H
R
O
RO
HO
R R
H+, RO-H
RO
RO
R R + H-O-H
Hemiketal Hemiketal intermediateintermediate
ketalketal
Hydrolysis of acetals and ketalsHydrolysis of acetals and ketals
“Cutting by water” is essentially the reverse of the addition of alcohol to either aldehyde or ketone.
aldehydealdehydeacetalacetal
RO
RO
R H +H
H
O H+ O
R H
2 R-OH+
alcoholalcohol
ketoneketoneketalketal alcoholalcohol
RO
RO
R R +H
H
O H+ O
R R
2 R-OH+
Intramolecular addition of alcohols to aldehydeIntramolecular addition of alcohols to aldehyde
C1 is hemiacetal carbon. Attached to it you will find: H, OH, OR and R, just like non-cyclical compounds.
Intramolecular Intramolecular hemiacetalhemiacetalglucoseglucose
C
C
C
C
CH2
C
OH
OH
OH
OH
HO H
H
H
H
H O1
2
3
4
5
6
*CH2OH
C
C
C C
O
C
6
5
4
3 2
1
OH
H
OH
OH
OH
H
H
H
H
Aldehyde Rxns – Testing for AldehydesAldehyde Rxns – Testing for Aldehydes
Benedict’s Reagent reacts with aldehydes that have an alcohol on the adjacent carbon (e.g., glucose)
Products include a red precipitate of copper (I) oxide
Tollens’ Reagent (reacts with all aldehydes)Tollens’ Reagent (reacts with all aldehydes)
Benedict’s Reagent (reacts with some aldehydes)Benedict’s Reagent (reacts with some aldehydes)
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