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Types of Chemical Reactions. Analysis of Reaction Ability of Alkanes, Arenes, Alcohols, Phenoles, Amines

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Types of Chemical Reactions. Analysis of Reaction Ability of Alkanes, Arenes, Alcohols, Phenoles, Amines Ministry of Public Health of Ukraine Ukrainian Medical Stomatological Academy Department of biological and bioorganic chemistry Types of chemical reactions. Analysis of reaction ability of alkanes, arenes, alcohols, phenoles, amines. Assoc. Prof. Bilets M.V. Lecture plan Classification of chemical reactions. Properties of nucleophiles and electrophiles. Saturated aliphatic hydrocarbons (alkanes). Unsaturated carbohydrates: alkenes, alkynes. Aromatic hydrocarbons (arenes). Hydroxyl compounds: alcohols and phenols. Amines. Classification of chemical reactions. https://pt.slideshare.net/antonio.delgado/tema-19-session1 Free radicals, nucleophiles, electrophiles Free radicals are molecules that have an unpaired (alone) electron. This makes them very unstable, and they rapidly combine with other species that are trying to gain a valence electron. Examples of free radicals Nucleophiles can donates a pair of electrons to an electrophile thereby forming a chemical bond. Examples of nucleophilic reagents Electrophiles have empty orbitals that are can attract electron pairs thereby forming chemical bonds. Examples of electrophilic reagents Saturated aliphatic hydrocarbons (alkanes). Condensed Alkanes are organic compounds that consist entirely Molecular Name Structural Formula of single-bonded carbon and hydrogen atoms and lack any Formula other functional groups. Methane CH CH Alkanes have the general formula CnH2n+2 and can be 4 4 subdivided into the following three groups: Ethane C2H6 CH3CH3 the linear straight-chain alkanes, branched alkanes, Propane C H CH CH CH and cycloalkanes. 3 8 3 2 3 Alkanes are the simplest and least Butane C4H10 CH3(CH2)2CH3 reactive hydrocarbon species containing only carbons and hydrogens. Pentane C5H12 CH3(CH2)3CH3 The names of all alkanes end with -ane. Whether or not the Hexane C6H14 CH3(CH2)4CH3 carbons are linked together end-to-end in a ring (called cyclic alkanes or cycloalkanes) Heptane C7H16 CH3(CH2)5CH3 or whether they contain side chains and branches, the name Octane C8H18 CH3(CH2)6CH3 of every carbon-hydrogen chain that lacks any double bonds or functional groups will end with the suffix -ane. Nonane C9H20 CH3(CH2)7CH3 Decane C10H22 CH3(CH2)8CH3 Chemical properties of alkanes Alkanes contain strong carbon-carbon single bonds and strong carbon-hydrogen bonds. The carbon-hydrogen bonds are only very slightly polar; therefore, there are no portions of the molecules that carry any significant amount of positive or negative charge that can attract other molecules or ions. Alkanes can be burned, destroying the entire molecule. Alkanes can react with some of the halogens, breaking carbon-hydrogen bonds. https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Supplemental_M odules_(Organic_Chemistry)/Alkanes/Reactivity_of_Alkanes/Halogenation_Al kanes Unsaturated carbohydrates: alkenes Alkenes are a class of hydrocarbons (e.g, containing only carbon and hydrogen) unsaturated compounds with at least one carbon-to-carbon double bond. Another term used to describe alkenes is olefins. Alkenes are more reactive than alkanes due to the presence of the double Alkenes have the general formula CnH2n. Nomenclature of alkenes: The ene suffix (ending) indicates an alkene or cycloalkene. The longest chain chosen for the root name must include both carbon atoms of the double bond. The root chain must be numbered from the end nearest a double bond carbon atom. If the double bond is in the center of the chain, the nearest substituent rule is used to determine the end where numbering starts. The smaller of the two numbers designating the carbon atoms of the double bond is used as the double bond locator. If more than one double bond is present the compound is https://esomake.co.ke/secondary/chemistry/organic-chemistry-I-alkynes- named as a diene, triene or equivalent prefix indicating form-three the number of double bonds, and each double bond is assigned a locator number. Chemical properties of alkenes Addition reactions Alkenes react in many addition reactions, Halogenation which occur by opening up the double-bond. It is the addition of elemental bromine or chlorine: Most of these addition reactions follow the CH =CH + Br → BrCH –CH Br mechanism of electrophilic addition. 2 2 2 2 2 Examples:halogenation, Hydrohalogenation hydrohalogenation, hydroxylation. It is the addition of hydrohalic acids., such as HCl or HI. CH3–CH=CH2+HI→CH3–CHI−CH2–H Hydration Hydration, the addition of water across the double bond of alkenes, yields alcohols. CH2=CH2 + H2O → CH3–CH2OH https://slideplayer.com/slide/9736825/ Markovnikov's rule When a protic acid HX (X = Cl, Br, I) or other polar reagent are added to an asymmetrically substituted alkene, addition of acidic hydrogen takes place at the less substituted carbon atom of the double bond, while halide X is added to the more alkyl substituted carbon atom. In other words, hydrogen is added to the carbon atom with more number of hydrogen atoms attached to it and halide is added to the carbon atom with least number of hydrogen atoms. https://slideplayer.com/slide/9736825/ Chemical properties of alkenes Oxidation Alkenes react with percarboxylic acids and even hydrogen peroxide to yield epoxides: RCH=CH2 + RO2H → RCHOCH2 + RO2H For ethylene, the epoxidation is conducted on a very large scale industrially. This commercial route uses oxygen in the presence of catalysts: C2H4 + 1/2 O2 → C2H4O Polymerization Polymerization of alkenes is a reaction that yields polymers of high industrial value at great economy, such as the plastics polyethylene and polypropylene Unsaturated carbohydrates: alkynes Alkynes are organic molecules made of one ore more carbon-carbon triple bonds. They are unsaturated hydrocarbons and are written in the empirical formula of CnH2n−2. They are unsaturated hydrocarbons. Alkynes use the ending –yne. Reactions of alkynes: Addition Reactions The principal reaction of the alkynes is addition across the triple bond to form alkanes. These addition reactions are analogous to those of the alkenes. Oxidation. Alkynes are oxidized by the same reagents that oxidize alkenes. Polymerization. Alkynes can be polymerized by both cationic and free‐radical methods. https://esomake.co.ke/secondary/chemistry/organic-chemistry-I-alkynes- form-three/ Aromatic hydrocarbons (arenes). Arenes are aromatic hydrocarbons. The term "aromatic" originally referred to their pleasant smells (e.g., from cinnamon bark, wintergreen leaves, vanilla beans and anise seeds), but now implies a particular sort of delocalized bonding. Aromatic hydrocarbons (or sometimes called arenes or aryl hydrocarbon) are hydrocarbons with sigma bonds and delocalized ππ electrons between carbon atoms forming rings. Examples of arenes. Common benzene derived compounds with various substituents. https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Supplemental_Modules_(Organic_Chemistry)/Arenes/Nom https://classnotes.org.in/class11/chemistry/hydrocarbons/ar enclature_of_Arenes enes/ Aromatic hydrocarbons (arenes). Nomenclature of benzene-derived compounds has multiple possible Reactions of the arenes: names The six electrons in benzene's delocalised system do not belong (such as common and systematic names) be associated with its to any one carbon and are free to move around the ring. structure. They provide benzene with a high electron density. Some common substituents, like NO2, Br, and Cl, can be named this way when it is Regions of high density tend to attract positive ions, or atoms with a partial positive charge; benzene, like the alkenes reacts attached to a phenyl group. Long chain carbons attached can also be with electrophiles. The reactions are much slower with benzene, named this way. due to the high energy required to disrupt the delocalised electron system. For example, chlorine (Cl) attached to a phenyl group would be named Benzene undergoes electrophilic substitution reactions: chlorobenzene (chloro + benzene). Instead of using numbers to indicate substituents on a benzene ring, ortho- (o-), meta- (m-), or para (p-) can be used in place of positional markers when there are two substituents on the benzene ring (disubstituted benzenes). They are defined as the following: ortho- (o-): 1,2- (next to each other in a benzene ring) meta- (m): 1,3- (separated by one carbon in a benzene ring) para- (p): 1,4- (across from each other in a benzene ring) http://www.4college.co.uk/a/Cd/react.php Examples of well-known organic compounds containing aromatic fragment. Hydroxyl compounds: alcohols. Alcohols are molecules containing the hydroxy functional group (-OH) that is bonded to the carbon atom. Alcohols are usually named by the first procedure and are designated by an -ol suffix. Some of the properties of alcohols depend on the number of carbon atoms attached to the specific carbon atom that is attached to the OH group. Alcohols can be grouped into three classes on this basis. A primary (1°) alcohol is one in which the carbon atom (in red) with the OH group is attached to one other carbon atom. Its general formula is RCH2OH. A secondary (2°) alcohol is one in which the carbon atom (in red) with the OH group is attached to two other carbon atoms (in blue). Its general formula is R2CHOH. A tertiary (3°) alcohol is one in which the carbon atom (in red) with the OH group is attached to three other carbon atoms (in blue). Its general formula is R3COH. Hydroxyl compounds: alcohols. Condensed Molecule can contain several HO groups. Alcohols Class Common IUPAC Structural bearing
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