1. Alcanos
Hidrocarburos
Son compuestos formados exclusivamente por carbono e hidrgeno.
Alcanos
Los alcanos son hidrocarburos saturados, estn formados exclusivamente por carbono e hidrgeno y nicamente hay enlaces sencillos en su estructura.
Frmula general: CnH2n+2 donde n represente el nmero de carbonos del alcano.
Esta frmula nos permite calcular la frmula molecular de un alcano. Por ejemplo para el alcano de 5 carbonos: C5H [(2 x 5) +2] = C5H12
Hidrocarburos.
Molculas que contienen slo hidrgeno y carbono (CxHy)
Familias de hidrocarburos:
HIDROCARBUROS
ACCLICOS
CCLICOS
CARBOCCLICOS
ALIFTICOS (ALICCLICOS)
AROMTICOS
Hidrocarburos acclicos
Alcanos: CnH2n+2 (enlaces )
Alquenos: CnH2n (enlaces )
Alquinos: CnH2n-2 (enlaces )
Hidrocarburos alicclicos
Cicloalcanos
Cicloalquenos
Cicloalquinos
Alcanos
El estado fsico de los 4 primeros alcanos: metano, etano, propano y butano es gaseoso.
Del pentano al hexadecano (16 tomos de carbono) son lquidos y a partir de heptadecano (17 tomos de carbono) son slidos.
El punto de fusin, de ebullicin y la densidad aumentan conforme aumenta el nmero de tomos de carbono.
Son insolubles en agua
Propiedades de los Alcanos
Pueden emplearse como disolventes para sustancias poco polares como grasas, aceites y ceras.
El gas de uso domstico es una mezcla de alcanos, principalmente propano.
El gas de los encendedores es butano.
El principal uso de los alcanos es como combustibles debido a la gran cantidad de calor que se libera en esta reaccin.
Propiedades de los Alcanos
8
Nomenclature:
The name of every organic molecule has 3 parts:
1. The parent name indicates the number of carbons in
the longest continuous chain.
2. The suffix indicates what functional group is present.
3. The prefix tells us the identity, location, and number of
substituents attached to the carbon chain.
Alkanes
9
The carbon substituents bonded to a long carbon chain are called alkyl groups.
An alkyl group is formed by removing one H atom from an alkane.
To name an alkyl group, change the ane ending of the parent alkane to yl. Thus, methane (CH4) becomes methyl (CH3-) and ethane (CH3CH3) becomes ethyl
(CH3CH2-).
Alkanes
Nomenclature:
10
Naming three- or four-carbon alkyl groups is more
complicated because the substituent can have isomeric
forms. For example, propane has both 1 and 2 H atoms, and removal of each of these H atoms forms a
different alkyl group with a different name, propyl or
isopropyl.
Alkanes
Nomenclature:
11
1. Find the parent carbon chain and add the suffix.
The parent is the longest continuous chain of carbon atoms.
Alkanes
Rule 1:
12
Note that if there are two chains of equal length, pick the
chain with more substituents to simplify naming. In the
following example, two different chains in the same
alkane have seven C atoms. We circle the longest
continuous chain as shown in the diagram on the left,
since this results in the greater number of substituents.
Alkanes
Nomenclature:
13
2. Number the atoms in the carbon chain from the end
that gives the first substituent the lowest number.
Alkanes
Rule 2:
14
If the first substituent is the same distance from both
ends, number the chain to give the second substituent
the lower number.
Alkanes
Nomenclature:
15
When numbering a carbon chain results in the same
numbers from either end of the chain, assign the lower
number alphabetically to the first substituent.
Alkanes
Nomenclature:
16
3. Name and number the substituents.
Name the substituents as alkyl groups.
Every carbon is part of the longest chain or a part of a substituent, not both.
Each substituent needs its own number.
If two or more identical substituents are bonded to the longest chain, use prefixes to indicate how many: di- for
two groups, tri- for three groups, tetra- for four groups,
etc.
Alkanes Rule 3:
17
4. Finally, write the name.
Substituent names and numbers come before the parent.
List substituents in alphabetical order, ignoring all prefixes except iso, as in isopropyl and isobutyl.
Separate numbers by commas and separate numbers from letters by hyphens. The name of an alkane is a
single word, with no spaces after hyphens and commas.
Alkanes
18
Carbon atoms in alkanes and other organic compounds are classified by the number of other carbons directly
bonded to them.
Alkanes Introduction:
19
Hydrogen atoms are classified as primary (1), secondary (2), or tertiary (3) depending on the type of carbon atom to which they are bonded.
Alkanes
Introduction:
20
Degrees of Substitution Primary (1) Carbon: carbon that is bonded to only one other carbon Secondary (2) Carbon: carbon that is bonded to two other carbons Tertiary (3) Carbon: carbon that is bonded to three other carbons Quarternary (4) Carbon: carbon that is bonded to four other carbons
1 Hydrogens- hydrogens on a primary carbon. -CH3 (methyl group) 2 Hydrogens- hydrogens on a secondary carbon. -CH2- (methylene group) 3 Hydrogens- hydrogens on a tertiary carbon. CH (methine group)
HO
Primary (1) Secondary (2) Tertiary (3)Quarternary (4)
secondaryalcohol
H3C CH2 CH
CH3
CH2 C
CH3
CH3
CH3
methyl group: 1 hydrogens methylene group: 2 hydrogens methine group: 3 hydrogens
21
The maximum number of possible constitutional isomers increases dramatically as the number of
carbon atoms in the alkane increases. For example,
there are 75 possible isomers for an alkane having 10
carbon atoms, but 366,319 possible isomers for one
having 20 carbons.
The suffix ane identifies a molecule as an alkane.
By increasing the number of carbons in an alkane by a CH2 group, one obtains a homologous series of alkanes, as shown in Table 4.1. The CH2 group is
called methylene.
Alkanes
Introduction:
1.- La base del nombre fundamental, es la cadena continua ms larga de tomos de carbono.
2.- La numeracin se inicia por el extremo ms cercano a una ramificacin.
Dos ramificaciones a la misma distancia, se empieza a numerar por el extremo ms cercano a la ramificacin de menor orden alfabtico.
Dos ramificaciones del mismo nombre a la misma distancia de cada uno de los extremos, se busca una tercera ramificacin y se numera la cadena por el extremo ms cercano a ella.
Nomenclatura de Alcanos
Hydrocarbons
CH4
C2H6
C3H8
C4H10
methane
ethane
propane
butane
C6H14
C7H16
C8H18
C9H20
C10H22
hexane
heptane
octane
nonane
decane
Prefix Suffix
meth-
eth-
prop-
but-
hex-
hept-
oct-
non-
dec-
-ane
-ane
-ane
-ane
-ane
-ane
-ane
-ane
-ane
Formula Name Structure
H
C
H
HH
H3C CH3
C5H12 pentanepent- -ane
Hydrocarbons
CH4
C2H6
C3H8
C4H10
methane
ethane
propane
butane
Prefix Suffix
meth-
eth-
prop-
but-
-ane
-ane
-ane
-ane
Formula Name Structure
H3C C CH3
H
H
H3C C C CH3
HH
H H
H
C
H
HH
or
or
H
C
H
CH H
H
H
C4H10 but- -ane H3C C CH3
CH3
H
or
Hydrocarbons
iso-butane
Hydrocarbons
C4H10 butane
Prefix Suffix
but- -ane
Formula Name Structure
H3C C C CH3
HH
H H
or
C4H10 iso-butanebut- -ane H3C C CH3
CH3
H
or
C5H12 pentanepent- -ane H3C C C C
HH
H H
H
H
CH3 or
H3C C C C
CH3H
H H
H
H
H
H C C C
CH3H
H CH3
H
H
H
or
or
C5H12 iso-pentanepent- -ane
C5H12 iso-pentane???pent- -ane
HydrocarbonsHydrocarbons
C4H10 butane
Prefix Suffix
but- -ane
Formula Name Structure
H3C C C CH3
HH
H H
or
C4H10 iso-butanebut- -ane H3C C CH3
CH3
H
or
C5H12 pentanepent- -ane H3C C C C
HH
H H
H
H
CH3 or
H3C C C C
CH3H
H H
H
H
H
H C C C
CH3H
H CH3
H
H
H
or
or
C5H12 iso-pentanepent- -ane
C5H12 neo-pentanepent- -ane
HydrocarbonsHydrocarbons
3.- Cuando en un compuestos hay dos o ms ramificaciones iguales:
4.- Se escriben las ramificaciones en orden alfabtico y el nombre del alcano que corresponda a la cadena principal.
Nomenclatura de Alcanos
Nomenclatura de Alcanos
Radicales alquilo Cuando alguno de los alcanos pierde un tomo de hidrgeno se forma un
radical alquilo. Estos radicales aparecen como ramificaciones sustituyendo tomos de hidrgeno en las cadenas.
IUPAC System of Naming Organic Compounds
pentaneH3C C C C
HH
H H
H
H
CH3
H3C C C C
CH3H
H H
H
H
H
H C C C
CH3H
H CH3
H
H
H
2-methylbutane
2,2-dimethylpropane
1. Find the longest carbon chain
2. Name all the atoms (other than H) not in the longest chain as groups
3. Number groups from the end of the chain closest to the first group
4. List multiple groups in alphabetical order,
1
2
3
4
5
Longest chain: pentane
Groups: none
IUPAC Name
12
34 Longest chain: butane
Groups: one methyl
12
34
not:
not: 3-methylbutane
12
3Longest chain: propane
Groups: two methyls
C4H10 butane
Prefix Suffix
but- -ane
Formula Structure
H3C C C CH3
HH
H H
or
C4H10 iso-butanebut- -ane H3C C CH3
CH3
H
C5H12 pentanepent- -ane H3C C C C
HH
H H
H
H
CH3
H3C C C C
CH3H
H H
H
H
H
H C C C
CH3H
H CH3
H
H
H
C5H12 pent- -ane
C5H12 pent- -ane
Hydrocarbons
IUPAC Name
2-methyl butane
2,2-dimethylpropane
IUPAC System of Naming Organic Compounds
CH3
C2H5
C4H9
methyl
ethyl
butyl
Prefix Suffix
meth-
eth-
but-
-yl
Group Formula Name Structure
C C C CH3
HH
H H
H
C
H
H
or
H
C
H
C H
H
H
-yl
-yl
H
H
C3H7 propylprop-C C CH3
H
H
or-yl
H
H
C3H7 iso-propyliso-prop-H3C C CH3
H
or-yl
Abbreviation
Me
Et
Pr
Bu
iPr
Naming Branches as Groups
Naming Branches as Groups
C4H9
sec-butyl
Group Formula Name Structure
C4H9
iso-butyl
C4H9 tert-butyl
Other Groups We May Encounter
C5H11 neo-pentyl
F
Cl
Br
I
bromo
fluoro
chloro
iodo
F
Cl
Br
I
Group Formula Name Structure
Naming Branches as Groups
34
Rules for Systematic Nomenclature of Alkanes
1. Find the parent chain
a. Identify the longest continuous carbon chain as the
parent chain.
b. If more than one different chains are of equal length
(number of carbons), choose the one with the greater
number of branch points (substituents) as the parent.
CH3 CHHC
CH2
CH2
CH2 CH2
CH3
CH3
CH3
7 carbons = hept-
CH3 CHHC
CH3
CH2
CH2 CH3
CH2 CH3 CH3 CH CH
CH3
CH2
CH2 CH3
CH2 CH3
2 branch pts. 1 branch pt.
35
2. Numbering the carbons of the parent chain
a. Number the carbon atoms of the parent chain so that any
branch points have the lowest possible number
b. If there is branching equidistant from both ends of the
parent chain, number so the second branch point has the
lowest number.
CH3 CHHC
CH2
CH2
CH2 CH2
CH3
CH3
CH3
CH3 CHHC
CH2
CH2
CH2 CH2
CH3
CH3
CH3
1
2
3
7 123
45
5
4
6
6
7
branch pts. at carbons 3 and 4 branch pts. at carbons 4 and 5
4
CH3 CH CH2
CH2
CH2 CH CH
CH3
CH2 CH3
1 2
3 5 6 7 8 9
H3C CH2 CH3
6
CH3 CH CH2
CH2
CH2 CH CH
CH3
CH2 CH3
9 8
7 5 4 3 2 1
H3C CH2 CH3
branch pts. at carbons 3, 6, 7 branch pts. at carbons 3,4,7
36
3. Substituents
a. Identify and number the substituents and list
them in alphabetical order.
b. If there are two substituents on the same carbon,
assign them the same number.
4. Write out the name
a. Write out the name as a single word:
hyphens (-) separate prefixes
commas (,) separate numbers
b. Substituents are listed in alphabetical order c. If two or more identical substituents are present use the
prefixes: di- for two
tri- for three
tetra- for four
6
CH3 CH CH2
CH2
CH2 CH CH
CH3
CH2 CH3
9 8
7 5 4 3 2 1
H3C CH2 CH3Parent C-9 = nonane3- ethyl4-methyl7-methyl
4,7-dimethyl
37
note: these prefixes (di-, tri-, tetra-, etc.) are not used for
alphabetizing purposes
6
CH3 CH CH2
CH2
CH2 CH CH
CH3
CH2 CH3
9 8
7 5 4 3 2 1
H3C CH2 CH3
3- ethyl-4,7-dimethylnonane
5. Complex Substituents (substituents with branching)
a. Named by applying the four previous rules with some
modification
b. Number the complex substituent separately from the parent.
Begin numbering at the point of attachment to the parent
chain
c. Complex substituents are set off by parenthesis.
CH3 CH CH2
CH3
CH2 CH CH CH2 CH2 CH2
H2C CH2
CH3
CH3
CH3
1 2 3 4 5 6 7 8 9 10
1 2 3 2,6-dimethyl-5-(1-methylpropyl)decane
CH2
38
Nonsystematic (trivial) Names:
3-carbons:
4-Carbons:
5- Carbons:
Alphabetizing trivial names:
Iso- and neo are part of the alkyl group name and are used for alphabetizing.
sec- and tert- are not included in the alphabetical order.
4-(1-methylethyl)heptane-or-
4-Isopropylheptane
2-methyl-6-(2-methylpropyl)decane-or-
6-Isobutyl-2-methyldecane
CH
H3C
H3C
Isopropyl-
(1-methylethyl)
Parent Chain
CH
CH2
H3C
Parent Chain
sec-butyl-
(1-methylpropyl)
Isobutyl-
(2-methylpropyl)
C
CH3
CH3
tert-butyl-
(1,1-dimethylethyl)
H3C
CH2Parent Chain
CH3
CHH3C H3CParent Chain
C
CH3
CH3
tert-pentyl-, tert-amyl
(1,1-dimethylpropyl)
CH2Parent ChainH3CCH2C
Parent ChainH3C
CH3
CH3
neopentyl-
(2,2-d imethylpropyl)
Isopentyl-, isoamyl
(3-methylbutyl)
CH2Parent Chain
CH2CH
H3C
H3C
Ejemplos de Alcanos
4-ETIL-2-METILHEPTANO
Ejemplos de Alcanos
5-ISOPROPIL-3- METILNONANO
3-METIL-5-n-PROPILOCTANO
EJEMPLOS DE ALCANOS
42
Alkanes
Physical Properties of Alkanes:
43
Alkanes
Physical Properties of Alkanes: