The History of Organic Chemistry | <>
The name organic chemistry came from the word organism. Prior to 1828, all organic compounds had been obtained from organisms or their remains. The scientific philosophy back then was that the synthesis of organic compounds could only be produced within living matter while inorganic compounds were synthesized from non-living matter. A theory known as "Vitalism" stated that a "vital force" from living organisms was necessary to make an organic compound. 1828, a German chemist Friedrich Wöhler (1800-1882) amazed the sience community by using the inorganic compound ammonium cyanate, NH4OCN to synthesize urea, H2NCONH2, an organic substance found in the urine of many animals. This led to the disappearance of the "Vitalism" theory. The Uniqueness of CarbonThere are more carbon compounds than there are compounds of all other elements combined. Plastics, foods, textiles, and many other common substances contain carbon. With oxygen and a metallic element, carbon forms many important carbonates, such as calcium carbonate (limestone) and sodium carbonate (soda). Certain active metals react with it to make industrially important carbides, such as silicon carbide, an abrasive known as carborundum, and tungsten carbide, an extremely hard substance used for rock drills and metalworking tools.The great number of carbon compounds is possible because of the ability of carbon to form strong covalent bonds to each other while also holding the atoms of other nonmetals strongly. Carbon atoms have the special property to bond with each other to form chains, ring, spheres, and tubes. Chains of carbon atoms can be thousands of atoms long, as in polyethylene. Polyethylene chain: H H H H H H H H H H H | | | | | | | | | | | H-C-C-C-C-C-C-C-C-C-C-C-etc. | | | | | | | | | | | H H H H H H H H H H H Structural IsomersIsomers are classified as structural isomers, which have the same number of atoms of each element in them and the same atomic weight but differ in the arrangement of atoms in the molecule. For example, there ware two compounds with the molecular formula C2H6O. One is ethanol (also called ethyl alcohol), CH3CH2OH, a colorless liquid alcohol; the other is dimethyl ether, CH3OCH3, a colorless gaseous ether. Among their different properties, ethanol has a boiling point of 78.5°C and a freezing point of -117°C; dimethyl ether has a boiling point of -25°C and a freezing point of -138°C. Ethanol and dimethyl ether are isomers because they differ in the way the atoms are joined together in their molecules. |
Acyclic Hydrocarbons
1.1 - The first four saturated unbranched acyclic hydrocarbons are called methane, ethane, propane and butane. Names of the higher members of this series consist of a numerical term, followed by "-ane" with elision of terminal "a" from the numerical term. Examples of these names are shown in the table below. The generic name of saturated acyclic hydrocarbons (branched or unbranched) is "alkane".Examples of names:
n | n |
1 Methane | 22 Docosane |
2 Ethane | 23 Tricosane |
3 Propane | 24 Tetracosane |
4 Butane | 25 Pentacosane |
5 Pentane | 26 Hexacosane |
6 Hexane | 27 Heptacosane |
7 Heptane | 28 Octacosane |
8 Octane | 29 Nonacosane |
9 Nonane | 30 Triacontane |
10 Decane | 31 Hentriacontane |
11 Undecane | 32 Dotriacontane |
12 Dodecane | 33 Tritriacontane |
13 Tridecane | 40 Tetracontane |
14 Tetradecane | 50 Pentacontane |
15 Pentadecane | 60 Hexacontane |
16 Hexadecane | 70 Heptacontane |
17 Heptadecane | 80 Octacontane |
18 Octadecane | 90 Nonacontane |
19 Nonadecane | 100 Hectane |
132 Dotriacontahectane | |
21 Henicosane |
1.2 - Univalent radicals derived from saturated unbranched acyclic hydrocarbons by removal of hydrogen from a terminal carbon atom are named by replacing the ending "-ane" of the name of the hydrocarbon by "-yl". The carbon atom with the free valence is numbered as 1. As a class, these radicals are called normal, or unbranched chain, alkyls.
Examples to Rule A-1.2
Alkanes | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
Alkanes are a hydrocarbon family that with carbon atoms that are only bonded to each other with single bonds. Alkanes have the general molecular formula, CnH2n+2, where n = number of carbon atoms in the alkane molecule. A normal hydrocarbon alkane is one where all the carbon atoms in the molecule are in a "continuous" chain. A continuous chain does not necessarily mean that the carbons are in a straight line. The carbons can be in a "zig zag" chain as long as the chain is connected by a carbon atom. The simplest alkane is methane, CH4. It is made from one carbon atom bonded to four hydrogen atoms. The table below shows the first ten alkanes.
Alkyl GroupsAn alkyl is basically an alkane minus one of its hydrogen atoms. For example: H H | remove one H | H-C-H ============> H-C- or CH3- | | H H methane methyl H H H H | | remove one H | | H-C-C-H ============> H-C-C- or CH3CH2- | | | | H H H H ethane ethyl Alkyl names are used to name branched alkanes. Any branch in an alkane would be named as the number of carbons + "yl". Rules for naming Alkanes
CycloalkanesCycloalkanes are alkanes in which a bond is formed between the two terminal carbons in the chain to for a cyclical or ring structure. The prefix cyclo- is written before the name designating the carbon number in the ring (e.g. cyclohexane).
CH2 / \ CH2-CH2 cyclopropane CH2-CH2 | | CH2-CH2 cyclobutane |
Alkenes | |||
Alkenes are hydrocarbons that contain one or more carbon-carbon double bonds. Alkenes with only one double bond have the general formula CnH2n Naming alkenes has the same format as naming alkanes, but be sure to change the -ane ending on the parent name to -ene ending. This shows that the compound is an alkene.
Example:
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Geometric Isomers | |
In alkanes, rotational freedom is possible but for alkenes, due to the carbon-carbon double bond, it is impossible to rotate the bond without breaking it. Geometric isomers are isomers that differ from each other based on the position of the attached groups relative to the double bond. Two substituents that are on the same side of the double bond is called cis, meaning "same", two substituents that are on the same side of the double bond is called trans, meaning "across". |
Alkynes |
Alkynes are hydrocarbons that have at least one triple covalent bond between two carbon atoms. The general formula for the Alkyne CnH2n-2. Similarly, alkynes are named just like alkenes only with the -yne ending instead of the -ene ending in naming compounds.
Example |
Aromatics | |||
Aromatics are carbon compounds that have benzene-like properties. The term "aromatic" came to be because earlier compounds found with the rings had pleasant fragrances, but it turns out that the ring has nothing to do with smell. Benzene, back then, had special properties and fascinated scientists for many years. At last, a structural model was proposed and accepted as the benzene ring. Aromatics consists of a benzene ring located anywhere within the molecular structure. If an alkyl group substitutes a hydrogen atom on the benzene ring, the structure is similarly named like an branched alkane.
If a benzene ring is considered a branch(in larger molecules), then the benzene ring is called a phenyl group. In this case, the alkane becomes the parent chain and the phenyl thus becomes a branch of the alkane structure. Eg. 1-phenylbutane
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Organic Halides |
Organic halides are organic compounds in which one or more hydrogen atoms have been substituted by a halogen atom. The IUPAC name for halides is the same as branched chain hydrocarbons. The branch is named by shortening the halogen name to fluoro-, chloro-, bromo-, or iodo-. The halide(s) are treated as branched groups and are located on the continuous chain of carbons as you would locate and name any alkyl branch.
Example: H H | | CH3-C-C-CH3 | | F F 1,2-difluorobutane |
Alcohols | ||||
All alcohols contain the hydroxyl functional group, -O-H, attached to single bonded hydrocarbons (alkanes). Alcohol have the general formula R-OH where R represents any chain of carbon and hydrogen atoms. The four most common alcohols are:
H | H H H-C-H H | | | | H-C-C---C---C-H | | | | H O H H | H Parent chain: butane -OH group location: 2 Substituents locations: 3-methyl Alkane name: 3-methylbutane Alcohol name: 3-methyl-2-butanol Alchohols containing more than one hydroxyl group are also called polyalcohols. Polyalcohols are named similarly to alcohols, with the exception of the prefix di-, tri-, etc before the -ol ending. Example: H H | | H-C-C-H | | OH OH 1,2-ethanediol H H H | | | H-C-C-C-H | | | OH OH OH 1,2,3-propanetriol |
Ethers | |
Ethers are compounds with two alkyl groups bonded to an oxygen atom. Ethers have the general formula R1-O-R2 where R1 and R2 are hydrocarbon groups. The difference between alcohol and ether are that in an alcohol, one hydrogen atom is replaced by an alkyl group. In an ether, however, both hydrogen atoms are replaced by alkyl groups. Simple ethers can be named by naming the alkyl groups alphebetically followed by the word "ether". A more efficient way of naming ethers would be by adding -oxy- to the prefix for the smaller hydrocarbon group and joining it to the alkane name of the larger hydrocarbon group. For example, CH3-O-CH2-CH3 would be called using this common name approach as Ethyl Methyl Ether and another way to name it would be methoxyethane. If just two alkyl groups are identical in its molecular formula, use the prefix di-, tri-, tetra-, etc to signify these branches. Eg. diethyl ether Example:
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Aldehydes | ||||
Aldehydes are a family of organic compounds that contain the carbonyl functional group, -CO-, and in which the carbonyl group is bonded to at least one hydrogen. The general formula for an aldehyde is RCHO, where R is hydrogen or an alkyl group. When naming aldehydes:
Example:
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Ketones | ||
Both aldehydes and ketones are often referred to as carbonyl compounds. The difference between aldehydes and ketones, however, lies in the atoms or groups to which the carbon of the carbonyl group is bonded. In aldehydes, at least one of the bonds is connected to a hydrogen atom, while in ketones neither bond is connected directly to hydrogen, but both are connected to carbon atoms. In naming ketones,
Examples:
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Carboxylic Acids | |||||
Carboxylic acids is a family of organic compounds that contains the carboxyl group, -COOH. which consists of a carbon atom joined to an oxygen atom by a double bond and to a hydroxyl group, OH, by a single bond.
Example:
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Esters |
Esters are a group of organic compounds with a general formula R1CO2R2 (where R1 and R2 are alkyl groups) that are formed, along with water, by the reaction of acids and alcohols. Natural occurring esters of organic acids in fruits and flowers give them their distinctive odors. It also also used for food aroma and taste, perfumes, synthetic fibres, and solvents. To name esters,
Example: CH3COOC7H14CH3 octyl ethanoate |
Amides | ||
Amide is a group of organic compounds containing the carbonyl group that is bonded to a nitrogen atom, CONH2 and, usually, a hydrocarbon. It is formed by the reaction of an ester with an amine. All amides are solids at room temperature and are neutral compounds, neither acidic nor basic since they are formed in a neutralization. To name amides,
Example:
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Amines | ||||
Amines are organic derivatives of ammonia, meaning that one, two, or three hydrocarbon groups have replaced the hydrogens. Amines have an extremely high solubility and have disagreeable odors (fish smell). Amines could be classified as primary, secondary, and tertiary depending on the amount of hydrogen that has been replaced by a hydrocarbon group. Amines could also be found in plants which are called alkaloids and affect the central nervous system of many creatures To name amines,
Example:
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Organic Reactions | <>
CrackingIn petroleum refining, cracking is a process by which heavy hydrocarbon molecules are broken up into lighter molecules by means of heat and usually pressure and sometimes catalysts. Cracking is the most important process for the commercial production of gasoline. Example: C22H44 => C12H20 + C10H24 C17H36 => C9H20 + C8H16 ReformingReforming is a processing technique in which the molecular structure of a hydrocarbon is rearranged to alter its properties. The process is frequently applied to low-quality gasoline stocks to improve their combustion characteristics. Opposite to cracking, reforming is used to create larger molecules of hydrocarbons from smaller ones. Example: C5H12 + C5H12 => C10H22 + H2 CombustionExample: 2C8H18 + 25O2 => 16CO2 + 18H2O + energy Addition (Hydrogenation)Hydrogenation is an addition reaction involving the combination of hydrogen with unsaturated hydrocarbons. Unsaturated organic compounds have at least one pair of carbon atoms bonded by a double or triple bond, alkenes and alkynes. Addition of hydrogens to alkenes and alkynes are called saturation reactions because the reaction causes the carbon atoms to become saturated with the maximum number of attached groups. Example: H H H H H H H H | | | | | | | | H-C=C-C-C-H + H-H => H-C-C-C-C-H | | | | | | H H H H H H butene + 2H => butane C3H4 + 2H-H => C3H8 propyne + 2H-H => propaneAside from alkenes and alkynes, halides also have the ability to add halogens to the carbons of double or triple bonds thus creating organic halides. Example: H H H H | | | | H-C=C-H + Cl-Cl => H-C-C-H | | Cl Cl ethene + chlorine => 1,2-dichlororethane C2H2 + Cl-Cl => C2H2B2 ethyne + bromine => 1,2-dibromoethene Still unsaturated, 1,2-dibromoethene could undergo another addition reaction to produce 1,1,2,2-tetrabromoethane. Br Br Br Br | | | | H-C=C-H + Br-Br => H-C-C-H | | Br Br 1,2-dibromoethene + bromine => 1,1,2,2-tetrabromoethane SubstitutionSubstition reaction is a chemical reaction that breaks apart a carbon-hydrogen bond and replaces the hydrogen atom with another atom or atom group. Example: H H H H H H | | | | | | H-C-C-C-H + Br-Br => H-C-C-C-H + H-Br | | | | | | H H H Br H H propane + bromine => 1-bromopropane + hydrogen bromideEliminationElimination is an chemical reaction in which a pair of atoms or groups of atoms are removed from a molecule by reacting it with an acid or a base. For organic reactions, an alkyl halide reacts with a hydroxide ion to produce an alkene and therefore removing a hydrogen atom and a halide ion from the molecule. Example: H H H H H H | | | | | | H-C-C-C-H + OH => H-C=C-C-H + H-O + Br | | | | | H BrH H H 2-bromopropane + hydroxide ion => propene + water + bromide ion Alcohols could also undergo elimination reactions by reacting with an acid to remove a hydrogen atom and a hydroxyl group thus producing alkenes. Example: H H H H | | | | H-C-C-H + acid => H-C=C-H + H-O | | | | H OH H H ethanol + acid => ethene + water CondensationCondensation is an organic reaction when two molecules combine, usually in the presence of a catalyst, with the elimination of water or some other simple molecule. Catalysts commonly used in condensation reactions include acids and bases. The combination of two identical molecules is known as self-condensation. This process forms larger molecules, many of which are useful in organic synthesis. Aldehydes, ketones, esters, alkynes, and alcohols are among several organic compounds that combine with each other to form larger molecules. Example: CH3OH + CH3OH => CH3OCH3 + HOH methanol + methanol => methoxymethane + waterFor a carboxylic acid undergoing condensation reaction, it combines with another reactant, forming two products - an organic compound and the byproduct of water. In an event when a carboxylic acid reacts with an alochol to produce an ester and water, this process is called esterification. Example: CH3COOH + HOCH3 => CH3COOCH3 + HOH ethanoic acid + methanol => methyl ethanoate + waterAddition PolymerizationPolymerization is a process in which very small molecules, called monomers, combine chemically with each other to produce a very large chainlike molecule, called a polymer. The monomer molecules may be all alike, or they may represent two, three, or more different compounds. The monomers react to form a polymer without the formation of by-products such as water. The structure has one structural unit, or monomer, that occurs repeatedly. Through polymerization of ethylene (ethene), CH2CH2, the structure of the polymer can therefore be represented by -(CH2CH2)n- Where n can be several thousand. Because of this, polymers have incredible molar masses up to millions of grams per mole. Example: H H H H H H H H H H H H | | | | | | | | | | | | C=C + C=C + C=C => :C-C:C-C:C-C: OR -(CH2CH2)n- | | | | | | | | | | | | H H H H H H H H H H H H ethylene part of polyethylene Condensation PolymerizationIn condensation polymerization, two functional groups of two different monomer molecules are joined together which produces a small molecule such as water. The monomers bond at where the hydrogen atoms were taken out to produce water. In order to become a condensed polymer, the monomer molecules must have at least two functional groups. The combination of two identical molecules is known as self-condensation. The reaction between a carboxylic acid and an alcohol creates an ester. If the carboxylic acid and the alcohol were the monomers of the polymer, during polymerization, they would create polyester, and produce water. The polymerization of a carboxylic acid and an amine similarly creates polyamides. Example: COOHC6H6COOH + HOCH2CH2OH => COOHC6H6OCH2CH2OH + HOH 1,4-benzenedioic acid + 1,2-ethandiol => polyester + water |
9.1- The Chemistry of Carbon Compounds |
-Classified compounds used to be classified as either organic or inorganic -A theory called “Vitalism” suggested that organic compounds needed a “vital force” in order to be synthesized -This theory was proven unacceptable by a lab experiment performed by the German chemist Friedrich Wöhler (1800-1882) in which he synthesized urea H2NCONH2 from the inorganic compound ammonium cyanate NH4OCN -The synthesis of acetic acid and sucrose from inorganic compounds also disproved of the theory -Organic chemistry is the study of molecular compounds. - Organic compounds are formed from covalent bonds within their molecules -Inorganic compounds consist of ionic bonds -Through technology compounds could be obtained from many ways such as mining -Carbon atoms can form four bonds which lets it have the ability to do single, double, and triple bonds -Carbon atoms can also bond together to form chains, rings, spheres, sheets, and tubes of any size -Molecular formulas help communicate the relative number of atoms present in a molecule and, in some cases, suggests a molecule’s structure -Isomers are substances with the same molecular formula but different structures -The possibility of various isomers increases dramatically as the number of carbon atoms in a molecule increases -To aid us in visualizing the structures of molecules, ball-and-stick models and space-filling models shows us the different aspects of molecules -Structural diagrams also called molecular structure -A complete structural diagram shows all the atoms and bonds -A condensed structural diagram omits the C-H bonds but shows all carbon-carbon bonds -A line structural diagram represents long chains of carbon atoms, the end of each line segment represents a carbon atom, and hydrogen atoms are not shown -Organic substances are classified into families based on the characteristic structures and bonds within the molecules -Functional groups are characteristic arrangement of atoms within a molecule that are believed to be largely responsible for properties of the compound -Hydroxyl functional group is determined by the presence of the –OH groups of atoms -Functional groups, sites where chemists believe reactions take place, help to explain many chemical properties of organic compounds |
9.2- Hydrocarbons |
-Hydrocarbons are compounds containing only carbon and hydrogen atoms -Hydrocarbons are the basis for synthesizing products like fuels, plastics -Refining is the technology that separates complex mixtures into purified components -Refining could include physical processes such as crushing and treating with solvents, solvent absorption, condensation, and distillation -Fractional distillation also called fractionation, is the process in which the differences in boiling points of the compounds making up petroleum enables the separation of these compounds -In a fractionating tower, crude oil is placed and heated at the bottom of the tower. Compounds with low boiling points vaporize and rise to the top of the tower and gradually condense. Substances that have high boiling points condense in the lower, hotter parts of the tower. -At various levels in the tower, trays collect mixtures of substances as they condense, each mixture containing compounds with similar boiling points -These mixtures are called petroleum fractions. -Fractions that have low boiling points are due to the fact that small molecules have smaller electrons unlike high boiling points containing large molecules -Cracking is the process in which hydrocarbons are broken down into smaller fragments occurring the absence of air eg. C17H36 => C9H20 + C8H16 -Reforming reaction is the opposite of cracking where large molecules are formed from smaller ones eg. C5H12 + C5H12 => C10H22 + H2 -It is used to convert low-grade gasolines into higher grades -Combustion is the process in which petroleum in used as fuels to produce energy eg. 2C8H18 + 25O2 => 16CO2 + 18H20 + energy -Alkanes are hydrocarbons whose empirical formula indicate only single carbon-to-carbon bonds -Each formula in the alkane series has one more CH2 group than the one preceding it eg. CH4 – methane , C2H6 – ethane -The general formula for all alkanes is CnHn+2 -The prefixes of alkane indicate the number of carbon atoms in the molecule -A branch is any group of atoms that is not part of the main structure of the molecule -In naming alkyl branches, the prefixes are followed by a –yl suffix -To name an isomer you identify the longest continuous chain of carbon atoms -Number the carbon atoms starting from the end closest to the branch H H H H | | | |H-C1-C2-C3-C4-H | | | | H H H H -Next, name the branch and their location number on the parent chain H | H-C-H <= methyl branch, located at #2 on parent chain | H | H H | | | |H-C-C-C-C-H | | | | H H H H-Write the complete IUPAC name following this format: (location of branch)-(branch name)(parent chain) -When writing the name of the alkane, the branches could be listed in alphabetical order or in the order of complexity -Cyclic hydrocarbons are hydrocarbons with a closed ring -If all the carbon-carbon bonds in a cyclic hydrocarbon are single bonds, the compound is a cycloalkane. eg. CH2 / \CH2-CH2cyclopropane-Hydrocarbons containing double or triple bonds are valuable in the petrochemical industry because they are the basis for manufacturing many products like plastic -Organic compounds with carbon-carbon double bonds are said to be unsaturated because fewer hydrogen atoms would be attached to the carbon atoms than that if all the bonds were single -Addition reaction are when unsaturated hydrocarbons react with small diatomic molecules such as bromine and hydrogen -Adding sufficient quantity, called hydrogenation, converts unsaturated hydrocarbons to saturated ones -Alkenes are hydrocarbons with carbon-carbon double bonds -Alkenes with only one double bond features the same prefixes used in naming alkanes, together with the suffix –ene -The general formula for all alkenes are C2H2n -Alkynes is explained by the presence of a triple bond between carbon atoms -Alkynes are named like alkenes, except for the –yne suffix -The general formula for all alkynes are CnH2n-2 -In naming alkenes and alkynes, the longest or parent chain must contain the multiple bond, and the chain is numbered form the end closest to the multiple bond -Also, the name of the parent chain is preceded by a number that indicates the position of the multiple bond on the parent chain -The location of the multiple bond in an alkyne precedes over the location of the branches in numbering the carbons of the parent chain -Geometric isomers for alkenes differ from each other with respect to the position of attached groups relative to the double bond -The term cis means that two attached groups are on the same side of the double bond -The term trans means that two attached groups are across from each other CH3 CH3 CH3 H \ / \ / C=C C=C / \ / \ H H H CH3 cis-2-butene trans-2-butene-Aromatic compounds are organic compounds with an aroma or odor -Aromatics is defined as benzene C6H6, and other carbon compounds with benzene-like structures and properties -Since the properties of benzene could not be explained by the accepted theories of bonding and reactivity, creating a visual model of a molecule of benzene proved difficult -Benzene, C6H6, has a melting point of 5.5°C and boiling point of 80.1°C and its molecules are non-polar. It is very unreactive with bromine, through X-Ray diffraction it shows all carbon-carbon bonds to be of same length -Also, through chemical reactions, it indicates that all carbons in benzene are identical and each carbon is bonded to one hydrogen -In 1865, German architect and chemist August Kekule (1829-1896) proposed a cyclic structure for benzene -Aliphatic compounds are organic compounds with chain or cyclic structures of single, double, or triple bonds -In naming aromatics, if an alkyl is bonded to a benzene ring, it is named as an alkylbenzene -No number is needed of the compound benzene since all carbon atoms are identical to each other -When two hydrogen atoms of the benzene ring have been replaced by an alkyl group, use the lowest pair of numbers to indicate the location of the two alkyl groups on the benzene ring. Numbering starts at one of the substituents and goes clockwise or counterclockwise to obtain the lowest possible pair of numbers -A benzene ring could be considered a branch if placed in larger molecules -In such cases, the benzene ring is called a phenyl group -Cracking = larger molecule + catalyst/heat => smaller molecules -Reforming = small molecules + catalyst/heat => larger molecules or one with more branches -Complete combustion = compound + O2 => CO2 +H2O -Addition (Hydrogenation) = alkene or alkyne + H2 => alkane |
9.3- Hydrocarbon Derivatives |
-Organic compounds are divided into two main classes: hydrocarbons and hydrocarbon derivatives -Hydrocarbon derivatives are molecular compounds of carbon and at least one other element that is not hydrogen -Organic halides are organic compounds in which one or more hydrogen atoms have been replaced by halogen atoms -Common organic halides include freons (chlorofluorocarbons) and Teflon (polytetrafluoroethylene) -Naming halides uses the same format as branched-chain hydrocarbons -The branch is named by shortening the halogen name to fluoro-, chloro-, bromo-, or iodo- -In drawing organic halides using IUPAC names, draw the parent chain and add branches at locations specified in the name eg. Cl Cl | | H-C-C-H | | H H1,2-dichloroethane-Organic halides react fast which is explained from the idea that no strong covalent bond is broken – the electron rearrangement does not involve separation of the carbon atoms -Addition of halogens could be added to alkynes which results in alkenes or alkanes -By adding halogens to alkenes, the product could undergo another addition step, by adding halogens to the parent chain, the double bond has to become a single bond in order to accommodate the halogens eg. Br Br Br Br | | | |H-C=C-H + Br-Br => H-C-C-H | | Br Br-By adding hydrogen halides to unsaturated compounds will produce isomers H H H H H H H H H | | | | | | | | |H-C=C-C-H + H-Cl => H-C-C-C-H OR H-C-C-C-H | | | | | | | H Cl H H HCl H-Substitution reaction is a reaction that involves the breaking of a carbon-hydrogen bond in an alkane or aromatic ring and the replacement of the hydrogen atom with another atom or group of atoms -With light energy it enables the substitution reaction to move at a noticeable rate eg. C3H8 + BR2 + light => C3H7Br + HBR -Through substitution reaction, in order to name the reaction product, just indicate the location number of the replacement, followed by the halogen prefix (eg. Bromo-) and then state the type of parent chain. Also indicate the second product created from substitution reaction (hydrogen bromide) eg. propane + bromine => 1-bromopropane + hydrogen bromide -Elimination is an organic reaction in which an alkyl halide reacts with hydroxide ion to produce an alkene by removing a hydrogen and halide ion from the molecule H H H H H H | | | | | | H-C-C-C-H + OH => H-C=C-C-H + H-O + Br | | | | | H BrH H H-Alcohols have properties that can be explained by the presence of a hydroxyl (-OH) functional group attached to a hydrocarbon chain -Short-chain alcohols are very soluble in water because they form hydrogen bonds with water molecules -Alcohols are used as solvents in organic reactions because they are effective for both polar and non-polar compounds -To name alcohols, the –e is dropped from the end of the alkane name and is replaced with –ol eg. Methane => methanol -Methanol is also called wood alcohol because it was once made by heating wood shavings in the absence of air -These days, methanol is prepared by combining carbon monoxide and hydrogen at high temperatures and pressure with the use of a catalyst -Methanol, however, is poisonous to humans. Consuming a small amount could cause blindness or death -When naming alcohols with more than two carbon atoms, the position of the hydroxyl group is indicated -Alcohols that contain more than one hydroxyl group are called polyalcohols, their names indicate the positions of the hydroxyl groups eg. 1,2-ethanediol -Alcohols undergo elimination reactions to produce alkenes through being catalyzed by concentrated sulfuric acid, which removes or eliminates a hydrogen atom and a hydroxyl group H H H H | | | |H-C-C-H + acid => H-C=C-H + H-O | | | H OH Hethanol + acid => ethene + water-Ethers is a family of organic compounds that contain an oxygen atom bonded between two hydrocarbon groups, and have the general formula R1-O-R2 -To name ethers add oxy to the prefix for the smaller hydrocarbon group and join it to the alkane name of the larger hydrocarbon group eg. CH3-O-C2H5 methoxyethane-Ethers have low solubility in water, low boiling points, and have no evidence of hydrogen bonding -Ethers undergo chemical change only when treated with powerful reagents under vigorous conditions -Ethers are formed by the condensation reaction of alcohols -Condensation reaction is the joining of two molecules and the elimination of a small molecule, usually water -The carbonyl functional group, -CO-, consists of a carbon atom with a double covalent bond to an oxygen atom -Aldehydes has the carbonyl group on the terminal carbon atom of a chain -To name aldehydes, replace the final –e of the name of the corresponding alkane with the suffix –al -Small aldehyde molecules have sharp, irritating odors whereas larger molecules have flowery odors and is used to make perfumes -A ketone has the carbonyl group present anywhere in a carbon chain except at the end of the chain -The difference in position of the carbonyl group affects the chemical reactivity, and enables us to distinguish aldehydes from ketones empirically -To name ketones, replace the –e ending of the name of the corresponding alkane with –one -The simplest ketone is acetone (propanone), CH3COCH3 -The family of organic compounds, carboxylic acids contain the carboxyl functional group, -COOH, which includes both the carbonyl and hydroxyl groups -Carboxylic acids are found in citrus fruits, and other foods with properties of having a sour taste -Carboxylic acids also have distinctive odors (like sweat from a person’s feet) -The molecules of carboxylic acids are polar and form hydrogen bonds both with each other and with water molecules -Carboxylic acids acid properties, so a litmus test can separate these compounds from other hydrocarbon derivatives -To name carboxylic acids, replace the –e ending of the alkane name with –oic, followed by the word “acid” -Methanoic acid, HCOOH, is the first member of the carboxylic acid family -Some acids contain two or three carbonyl groups such as oxalic acid, and citric acid COOH CH2-COOH | | COOH HO-C-COOH | CH2-COOH oxalic acid citric acid-When carboxylic acids undergo a condensation reaction, in which a carboxylic acid combines with another reactant, it forms two products – an organic compound and water -Esterification is the condensation reaction in which a carboxylic acid reacts with an alcohol to produce ester and water -carboxylic acid + alcohol => ester + water -The ester functional group is similar to that of an acid, except that the hydrogen atom of the carboxyl group is replaced by a hydrocarbon branch -Esters are responsible for the odors of fruits and flowers and are also added to foods for aroma and taste -To name an ester, determine name of the alkyl group from the alcohol used in the esterification reaction -Next change the ending of the acid name from “–oic acid” to “–oate” -ethanoic acid + methanol => methyl ethanoate + water -Artificial flavorings are made by mixing synthetic esters to give similar odors of the natural substance -An amide consists of a carboxyl group bonded to a nitrogen atom -Amides could be formed in condensation reactions -Amides occur in proteins, the large molecules found in all living organisms -Peptide bonds is the joining of amino acids together in proteins -To name amides, have the name of the alkane with the same number of carbon atoms, with the final –e replaced by the suffix –amide -Change the suffix of the carboxylic acid from “–oic acid” to –amide to have the same name results eg. ethanamide -Amines consist of one or more hydrocarbon groups bonded to a nitrogen atom -Through X-Ray diffraction reveals that the amine functional group is a nitrogen atom bonded by single covalent bonds to one, two, or three carbon atoms -Amines are polar substances that re extremely soluble in water as they form strong hydrogen bonds both to each other and to water -Amines have peculiar, horrible odors (eg. smell of rotting fish) -The name of amines include the names of the alkyl groups attached to the nitrogen atom, followed by the suffix –amine eg. methylamine -Amines with one, two, or three hydrocarbon groups attached to the central nitrogen atom are referred to as primary, secondary, and tertiary -Primary amines is when a hydrogen atom attached to the nitrogen atom is replaced by a hydrocarbon group -Secondary amines are when two hydrocarbon groups replaces the hydrogen atoms and tertiary amines replaces all of the hydrogen atoms with hydrocarbon groups -Amines are used in the synthesis of medicines -A group of amines found in many plants are called alkaloids -Many alkaloids influence the function of the central nervous systems of animals -Substitution – alkane/aromatic + halogen + light => organic halide + hydrogen halide -Elimination – alkyl halide + OH => alkene + water |+ water + halide ion -Elimination – alcohol + acid => alkene + water |
9.4- Synthesizing Organic Compounds |
-Synthesizing organic compounds help to show a new type of reaction -Organic compounds are synthesized chemically and also extracted from living systems -Polymerization is the formation of very large molecules (polymers) from many small molecular units (monomers) -Polymers are substances whose molecules are made up of many small molecules linked together in long chains -Polymers have molar masses up to millions of grams per mole -Addition polymerization is the polymerizing of alkane molecules -Polyethylene, for example, is made by polymerizing ethene molecules -Addition polymers are formed when monomer units join together in a process that rearranges electrons in double or triple bonds in the monomer -In addition polymerization, the polymer is the only product formed -Condensation polymerization involves the formation of a small molecule from the functional group of two different monomer molecules -Monomer molecules bond at sites where atoms are removed from their functional groups -In order to form a condensation reaction, monomer molecules must have at least two functional groups, therefore they are bifunctional -Polyester is a polymer formed from the reaction of a bifunctional acid monomer with a bifunctional alcohol monomer -The result ester has a free hydroxyl group at one end and a free carboxyl at the other end -Because of this, further reactions could occur at either ends of the ester -A polyamide is a large molecule formed when a bifunctional acid monomer reacts with a bifunctional amine monomer -proteins are a basic structural material in plants and animals -There are over 10 billion different proteins in Earth’s living organisms, and are constructed from only about 20 amino acids -Amino acids are structurally bifunctional, containing both an amine group (-NH2) and a carboxyl group (-COOH) - Condensation polymerization occurs for sugar molecules in which a water is molecule is formed and the monomers join together to form a larger molecule -The carbon cycle is a cycle in which atoms of carbon move throughout the biosphere of our planet |
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