HETEROATOMS
• Halogens take the place of hydrogens, so add their number to the number of H’s.
• Oxygen doesn’t change the C:H ratio, so ignore oxygen in the formula.
• Nitrogen is trivalent, so it acts like half a carbon.
H H H
-C - C - N - C -
H H H H
Problem:
Why the Nitrogen can be change carbon and what the function!
about heteroatoms:
Heteroatom Chemistry is designed to bring together a broad,
interdisciplinary group of chemists who work with compounds containing
main-group elements of groups 13 through 17 of the Periodic Table and
certain other related elements. The fundamental reactivity should, in all
cases, be concentrated about the heteroatoms. It does not matter whether the
compounds being studied are acyclic or cyclic; saturated or unsaturated; of
a monomeric, polymeric or solid state nature; inorganic, organic or
naturally occurring, so long as the heteroatom is playing an essential role.
Also, both experimental articles and those based on computational chemistry are welcomed. In general, Heteratom Chemistry will not accept manuscripts based on classical heterocyclic chemistry (for which several special
journals are available). It welcomes, however, interesting articles on
heterocyclic systems beyond the scope of classical organic chemistry.
On a more positive note, there are many areas of research that are
unmistakable examples of heteroatom chemistry. These include structures and
reactions that exhibit:
(a) unusual valency of highly coordinated main-group element compounds;
(b) characteristics and unusual properties of low coordinate main-group
element compounds;
(c) characteristics and unusual properties of highly strained main-group
element compounds;
(d) similarities between main-group compounds and transition metal
compounds;
(e) facile photochemical or thermal cleavage of bonds involving heteroatoms
that lead to highly reactive intermediate species;
(f) the unusual reactivity of compounds that contain multiply bonded
heteroatoms;
(g) the unusual structures and reactivities of highly catenated heteroatoms;
(h) specific and unusual neighboring group effects of heteroatoms on
physical and chemical properties of compounds;
(i) useful influences on synthetic processes; and
(j) wide applicability over many elements of the Periodic Table, e.g.,
ligand coupling within hypervalent species; variations on the immensely
important Wittig reactions; and the stereochemistry of compounds based on
the influence of heteroatoms present in the molecules.
These statements are not designed to limit the scope of heteroatom
chemistry; rather, they are intended to illustrate the many ways in which
heteroatoms play essential roles in the chemistry of compounds containing
them.
Sabtu, 19 Maret 2011
Kamis, 17 Maret 2011
alkene
Many important organic chemistry molecules contain oxygen or nitrogen. It's a good idea to memorize the names and structures of these functional groups, or at least bookmark the page to consult as needed.
Functional groups are groups of atoms found within molecules that are involved in the chemical reactions characteristic of those molecules. Functional groups can pertain to any molecules, but you will usually hear about them in the context of organic chemistry. The symbol R and R' refer to an attached hydrogen or hydrocarbon side chain or sometimes to any group of atoms.
Such a huge number of organic compounds requires organization. They are sorted into organic families defined by functional groups. Functional groups are small structural units within molecules at which most of the compound's chemical reactions occur.
For example, two of the most important families are the alcohols and the carboxylic acids. Their functional groups, the alcohol group and the carboxyl group, respectively, distinguishes them from the rest of the other types of organic compounds.
For example, two of the most important families are the alcohols and the carboxylic acids. Their functional groups, the alcohol group and the carboxyl group, respectively, distinguishes them from the rest of the other types of organic compounds.
Important Families of Organic Compounds
Symbolism shown below that you may not understand will be explained later in this topic
Symbolism shown below that you may not understand will be explained later in this topic
Hydrocarbons | Only C and H present |
Alkanes | Only single bonds |
Alkenes | Double bond(s) between two carbons |
Alkynes | Triple bond(s) between two carbons |
Aromatic |  |
Alcohols |  |
Ethers |  |
Aldehydes |  |
Ketones |  |
Carboxylic Acids |  |
Esters |  |
Amines |  |
Amides |  |
R, R', and R'' represent hydrocarbon groups (alkyl groups)
The type of properties associated with a compound is different depending on the family it is in. For example, the alkanes have just C-C and C-H single bonds. Since C and H are so alike in electronegativity, they are least able to attract ions or polar molecules, and least able to interact with them. The significance of this will be explained later.
Condensed Structures
To save space and time, condensed structures may be used to simplify the drawing and writing of structural formulas of organic compounds. C-H bonds are understood, and CH3 means that three hydrogen atoms are bonded to a carbon atom. For example:
CH3 is understood to be | H | H-C- | H |
CH3CH2OH is understood to be | H H | | H-C-C-O-H | | H H |
CH3OCH2 is understood to be | H H | | H-C-O-C-H | | H H |
Functional Groups and Polar Reactants
When a polar group of atoms, like the OH group or NH group are attached to a carbon, the molecule has a polar site. It may undergo chemical reactions when it attracts polar and ionic reactants, but it will usually be near this functional group. This is why compounds with the same functional group have similar chemical properties, or kinds of reactions. For example, in the amine group, both methylamine and ethylamine give the same kinds of reactions.
CH3NH2 + HCl ==> CH3NH3+ + Cl-
methylamine + hydrogen chloride ==> methylammonium ion + chloride ion
CH3CH2NH2 + HCl ==> CH3CH2NH3+ + Cl-
ethylamine + hydrogen chloride ==> ethylammonium ion + chloride ion
Only the NH2 group of the amines change in the previous two reactions, and it changes the same way in both.
CH3NH2 + HCl ==> CH3NH3+ + Cl-
methylamine + hydrogen chloride ==> methylammonium ion + chloride ion
CH3CH2NH2 + HCl ==> CH3CH2NH3+ + Cl-
ethylamine + hydrogen chloride ==> ethylammonium ion + chloride ion
Only the NH2 group of the amines change in the previous two reactions, and it changes the same way in both.
The Symbol R in Structural Formulas
The symbol R, stands for the word radical, and in organic chemistry, represents alkane-like groups. It is sometimes used to simplify equations or to summarize them. For example, to summarize the two equations in the previous sections, you may write:
RNH2 + HCl ==> RHN3 + Cl-
The R takes care of any alkane group that you may substitute in. It takes care of all the equations, including methylamine, ethylamine, propylamine, butylamine, etc. It gives a simpler view of how one group, not just the individual compound, changes into another and how each group affects its properties.
RNH2 + HCl ==> RHN3 + Cl-
The R takes care of any alkane group that you may substitute in. It takes care of all the equations, including methylamine, ethylamine, propylamine, butylamine, etc. It gives a simpler view of how one group, not just the individual compound, changes into another and how each group affects its properties.
• Pi bond is the functional group.
• More reactive than sigma bond.
• Bond dissociation energies:
Ø C=C BDE 146 kcal/mol
Ø C-C BDE -83 kcal/mol
Pi bond 63 kcal/mol
The explanation;
If we want t o dissociation C double bond change to be C single bond, it will needed energy .
The energy need to dissociation C=C is 146 Kkal/J, and the energy need to dissociation C-C is -83 Kkal/J. so, the condition to dissociation double bond change to single bond is:
63≤x<83.
Minggu, 13 Maret 2011
Reaction of alkane
Some of the alkene is difficult to react, why not?
Answer: because the alkene bond on the saturated purpose of which is saturated bond orbitals.
Change the 3,4,5 trimethyl nonane compounds into n-butene:
H H H H H H H H H
H-C - C - C - C - C - C - C - C - C - H
H H CH3 CH3 CH3 H H H H
From the structure above robahlah into the form of n-butene
The first thing we do is determine based on the reaction simpul-simpul/pusat-pusat pragmen and target compounds will be changed into the form of n-butene
H H H H H H H H H
H - C - C - C - C - C - C - C - C - C - H
H H CH3 CH3 CH3 H H H H
From the node that has the mark on so we can get some stricture of n-butene, namely
1.n-butene
H H H
H- C - C - C - H
H H CH3
2. n-butene
H H
H- C- C- H
CH3 CH3
3. n-butene
H H H H
H- c - C - C - C - H
H H H H
Some of the alkene is difficult to react, why not?
Answer: because the alkene bond on the saturated purpose of which is saturated bond orbitals.
Change the 3,4,5 trimethyl nonane compounds into n-butene:
H H H H H H H H H
H-C - C - C - C - C - C - C - C - C - H
H H CH3 CH3 CH3 H H H H
From the structure above robahlah into the form of n-butene
The first thing we do is determine based on the reaction simpul-simpul/pusat-pusat pragmen and target compounds will be changed into the form of n-butene
H H H H H H H H H
H - C - C - C - C - C - C - C - C - C - H
H H CH3 CH3 CH3 H H H H
From the node that has the mark on so we can get some stricture of n-butene, namely
1.n-butene
H H H
H- C - C - C - H
H H CH3
2. n-butene
H H
H- C- C- H
CH3 CH3
3. n-butene
H H H H
H- c - C - C - C - H
H H H H
reactions of alkane
Alkane Reactions
The alkanes and cycloalkanes, with the exception of cyclopropane, are probably the least chemically reactive class of organic compounds. Despite their relative inertness, alkanes undergo several important reactions that are discussed in the following section.
1. Combustion
The combustion of carbon compounds, especially hydrocarbons, has been the most important source of heat energy for human civilizations throughout recorded history. The practical importance of this reaction cannot be denied, but the massive and uncontrolled chemical changes that take place in combustion make it difficult to deduce mechanistic paths. Using the combustion of propane as an example, we see from the following equation that every covalent bond in the reactants has been broken and an entirely new set of covalent bonds have formed in the products. No other common reaction involves such a profound and pervasive change, and the mechanism of combustion is so complex that chemists are just beginning to explore and understand some of its elementary features.
CH3-CH2-CH3 + 5 O2 ——> 3 CO2 + 4 H2O + heat
Two points concerning this reaction are important:
1. Since all the covalent bonds in the reactant molecules are broken, the quantity of heat evolved in this reaction is related to the strength of these bonds (and, of course, the strength of the bonds formed in the products). Precise heats of combustion measurements can provide useful iinformation about the structure of molecules.
2. The stoichiometry of the reactants is important. If insufficient oxygen is supplied some of the products will consist of carbon monoxide, a highly toxic gas.
CH3-CH2-CH3 + 4 O2 ——> CO2 + 2 CO + 4 H2O + heat
The alkanes and cycloalkanes, with the exception of cyclopropane, are probably the least chemically reactive class of organic compounds. Despite their relative inertness, alkanes undergo several important reactions that are discussed in the following section.
1. Combustion
The combustion of carbon compounds, especially hydrocarbons, has been the most important source of heat energy for human civilizations throughout recorded history. The practical importance of this reaction cannot be denied, but the massive and uncontrolled chemical changes that take place in combustion make it difficult to deduce mechanistic paths. Using the combustion of propane as an example, we see from the following equation that every covalent bond in the reactants has been broken and an entirely new set of covalent bonds have formed in the products. No other common reaction involves such a profound and pervasive change, and the mechanism of combustion is so complex that chemists are just beginning to explore and understand some of its elementary features.
CH3-CH2-CH3 + 5 O2 ——> 3 CO2 + 4 H2O + heat
Two points concerning this reaction are important:
1. Since all the covalent bonds in the reactant molecules are broken, the quantity of heat evolved in this reaction is related to the strength of these bonds (and, of course, the strength of the bonds formed in the products). Precise heats of combustion measurements can provide useful iinformation about the structure of molecules.
2. The stoichiometry of the reactants is important. If insufficient oxygen is supplied some of the products will consist of carbon monoxide, a highly toxic gas.
CH3-CH2-CH3 + 4 O2 ——> CO2 + 2 CO + 4 H2O + heat
reactions of alkane
Reactions of alkane
Why mostly alkane compound are inert?
Answe : because it binds saturated making it difficult to react, the purpose of which is saturated akatan is bonding. In addition, because energy ionisasinya tingg, because ionitu require extra conditions for single bonds can decide ties.
Minggu, 06 Maret 2011
aromatic compound
AROMATIC COMPOUNDS
l alifatis compounds: methane derivatives
l aromatic compounds: benzene derivatives (symbol Ar = aryl)
l The beginning of the 19th century found the organic compounds that have a smell (scent) that the characteristics that come from plants (benzoin resin, cumarin, cinnamic acid, etc.)
Benzene = C6H6
l The most simple aromatic compounds
l Derived from coal and petroleum
l Physical properties: fluid, td. 80oC, colorless, insoluble in water, soluble in most organic solvents, flammable with a sooty flame and colored (because of the high C content)
Use of benzene:
l In the past as a motor fuel
l The solvent for many substances
l Synthesis: styrene, phenol, nylon, aniline, isopropyl benzene, detergents, insecticides, maleic acid anhydride, etc
l aromatic compounds: benzene derivatives (symbol Ar = aryl)
l The beginning of the 19th century found the organic compounds that have a smell (scent) that the characteristics that come from plants (benzoin resin, cumarin, cinnamic acid, etc.)
Benzene = C6H6
l The most simple aromatic compounds
l Derived from coal and petroleum
l Physical properties: fluid, td. 80oC, colorless, insoluble in water, soluble in most organic solvents, flammable with a sooty flame and colored (because of the high C content)
Use of benzene:
l In the past as a motor fuel
l The solvent for many substances
l Synthesis: styrene, phenol, nylon, aniline, isopropyl benzene, detergents, insecticides, maleic acid anhydride, etc
One fact shows that although benzene compounds have double bonds but it can not react with KMnO4 (oxidized) and undergo electrophilic addition reactions such as alkene compounds.
This is due to benzene compounds having double bonds can resonate so intermittent alternating double bond character is lost.
Benzene:
Evidence that the double bond character is missing from the bond length of each bond in benzene. If there is still a long double bond C = C bond should be a single bond 1:34 and 1:54 Å Å. In fact CC bond length of benzene is the same, namely 1:40 Å
Other evidence is to measure the thermodynamic heat of hydrogenation. Supposed to heat the hydrogenation of cyclohexene was 28.6 kcal per mole. For the three double bond of 1,3,5 sikloheksatriena should heat of hydrogenation is 85.8 kcal per mole. But the fact that benzene has a lower heat of hydrogenation of 36 kcal / mole. And the excess energy is called resonance energy of benzene, which is characteristic of aromatic compounds
Depictions of the molecular orbitals can better explain the nature kearomatisan of benzene. Benzene has a planar hexagon shape which all the atoms form sp2 Cnya with CC bond lengths are all the same. As shown in the figure below, six p orbitals for each carbon overlapping each other to form six molecular orbitals are divided into three bonding orbitals and the three orbital antiikatan. In the bond orbital lowest energy valence electrons which 12 have overlapping benzene rings perfect that thermodynamically and chemically more stable.
TERMS OF AROMATIC COMPOUNDS
Not all compounds that have double bonds that berselangseling with single bonds (a conjugated double bond) can be classified as an aromatic compound
Which includes aromatic compounds the conditions are:
1. Sp2 atoms in a ring oriented in the planar molecular shape (near-planar), the p orbital parallel to each other in the same direction
2. Meet the Huckel rule is л = 4n +2 for n price aromatic compound must be an integer
This is due to benzene compounds having double bonds can resonate so intermittent alternating double bond character is lost.
Benzene:
Evidence that the double bond character is missing from the bond length of each bond in benzene. If there is still a long double bond C = C bond should be a single bond 1:34 and 1:54 Å Å. In fact CC bond length of benzene is the same, namely 1:40 Å
Other evidence is to measure the thermodynamic heat of hydrogenation. Supposed to heat the hydrogenation of cyclohexene was 28.6 kcal per mole. For the three double bond of 1,3,5 sikloheksatriena should heat of hydrogenation is 85.8 kcal per mole. But the fact that benzene has a lower heat of hydrogenation of 36 kcal / mole. And the excess energy is called resonance energy of benzene, which is characteristic of aromatic compounds
Depictions of the molecular orbitals can better explain the nature kearomatisan of benzene. Benzene has a planar hexagon shape which all the atoms form sp2 Cnya with CC bond lengths are all the same. As shown in the figure below, six p orbitals for each carbon overlapping each other to form six molecular orbitals are divided into three bonding orbitals and the three orbital antiikatan. In the bond orbital lowest energy valence electrons which 12 have overlapping benzene rings perfect that thermodynamically and chemically more stable.
TERMS OF AROMATIC COMPOUNDS
Not all compounds that have double bonds that berselangseling with single bonds (a conjugated double bond) can be classified as an aromatic compound
Which includes aromatic compounds the conditions are:
1. Sp2 atoms in a ring oriented in the planar molecular shape (near-planar), the p orbital parallel to each other in the same direction
2. Meet the Huckel rule is л = 4n +2 for n price aromatic compound must be an integer
ORGANIK CHEMISTRY I
reguler2009@gmail.comElsa Yanti Mala
RSA1C110010
kelas PG-SBI kimia
Angkatan 2010
alamat blog: http://elsa.yantimala.blogspot.com
ORGANIC CHEMISTRY
Hydrocarbons
Problem:
1. Why are nonpolar hydrocarbons?
2. Which is most randah nonpolarnya of alkanes, alkenes, and alkyne?
3. Why are ripe fruits produce ethylene gas? And Why the immature fruits do not contain ethylene gas?
4. Why are the tomatoes ripe yet when placed together with a ripe tomato in a place so immature fruit will be quickly cooked, what causes it?
RSA1C110010
kelas PG-SBI kimia
Angkatan 2010
alamat blog: http://elsa.yantimala.blogspot.com
Hydrocarbons
Problem:
1. Why are nonpolar hydrocarbons?
2. Which is most randah nonpolarnya of alkanes, alkenes, and alkyne?
3. Why are ripe fruits produce ethylene gas? And Why the immature fruits do not contain ethylene gas?
4. Why are the tomatoes ripe yet when placed together with a ripe tomato in a place so immature fruit will be quickly cooked, what causes it?
Problem solving:
1. One of the properties of hydrocarbon compounds are nonpolar. Because it is nonpolar hydrocarbon compounds are not soluble in hydrocarbon air.selain Because it has no positive and negative poles because it only consists of atomic H and C that have no free electron pair.
2. Among the three alkanes, alkenes, and alkyne lowest alkyne nonpolarnya is because among the three compounds on the most easily soluble in water is alkyne and alkenes and alkanes are compounds that can not dissolve in water.
3. Ethylene gas is a growth hormone that is produced from normal metabolism in plants. Ethylene gas plays a role in the process of fruit ripening and leaf loss. This gas is colorless and easy menguap.Dalam fruit ripening, ethylene acts by breaking chlorophyll in young fruit, making fruit has only xantofil and carotene. Thus, the color becomes orange or red fruit.
Another function of ethylene gas in particular are:
• End the period of dormancy
• Stimulate the growth of roots and stems
• Formation of adventitious roots
• Stimulate absisi fruit and leaves
• Stimulate interest induction Bromiliad
• Induction of female sex cells of interest
• Stimulate the expansion rate
4. To accelerate the ripening process, it takes carbon dioxide and ethylene gas. ethylene gas is a plant hormone that accelerates the growth of plants. However, once picked, the fruit no longer get the ethylene gas that fruits have to obtain ethylene gas from the environment. Therefore, immature tomatoes should have ethylene gas from the environment to accelerate pematangannya. These gases can be obtained from ripe tomatoes by the gas to evaporate so that when in place along the immature fruit will quickly become mature.
1. One of the properties of hydrocarbon compounds are nonpolar. Because it is nonpolar hydrocarbon compounds are not soluble in hydrocarbon air.selain Because it has no positive and negative poles because it only consists of atomic H and C that have no free electron pair.
2. Among the three alkanes, alkenes, and alkyne lowest alkyne nonpolarnya is because among the three compounds on the most easily soluble in water is alkyne and alkenes and alkanes are compounds that can not dissolve in water.
3. Ethylene gas is a growth hormone that is produced from normal metabolism in plants. Ethylene gas plays a role in the process of fruit ripening and leaf loss. This gas is colorless and easy menguap.Dalam fruit ripening, ethylene acts by breaking chlorophyll in young fruit, making fruit has only xantofil and carotene. Thus, the color becomes orange or red fruit.
Another function of ethylene gas in particular are:
• End the period of dormancy
• Stimulate the growth of roots and stems
• Formation of adventitious roots
• Stimulate absisi fruit and leaves
• Stimulate interest induction Bromiliad
• Induction of female sex cells of interest
• Stimulate the expansion rate
4. To accelerate the ripening process, it takes carbon dioxide and ethylene gas. ethylene gas is a plant hormone that accelerates the growth of plants. However, once picked, the fruit no longer get the ethylene gas that fruits have to obtain ethylene gas from the environment. Therefore, immature tomatoes should have ethylene gas from the environment to accelerate pematangannya. These gases can be obtained from ripe tomatoes by the gas to evaporate so that when in place along the immature fruit will quickly become mature.
Langganan:
Postingan (Atom)