9.3- Hydrocarbon Derivatives |
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-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one other element that is not hydrogen -Organic halides are organic compounds in which one or more hydrogen atoms have been replaced by halogen atoms -Common organic halides include freons (chlorofluorocarbons) and Teflon (polytetrafluoroethylene) -Naming halides uses the same format as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
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H-C-C-H
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H H
-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
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H-C=C-H + Br-Br => H-C-C-H
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Br Br
-By adding hydrogen halides to unsaturated compounds will produce isomers
H H H H H H H H H
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H-C=C-C-H + H-Cl => H-C-C-C-H OR H-C-C-C-H
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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 H -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 -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
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COOH HO-C-COOH
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CH2-COOH
-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 |
