Ministry of Public Health of Ukraine Ukrainian Medical Stomatological Academy Department of biological and bioorganic

Types of chemical reactions. Analysis of reaction ability of , arenes, alcohols, phenoles, amines.

Assoc. Prof. Bilets M.V. Lecture plan

 Classification of chemical reactions.  Properties of nucleophiles and electrophiles.  Saturated aliphatic (alkanes).  Unsaturated carbohydrates: , .  Aromatic hydrocarbons (arenes).  Hydroxyl compounds: alcohols and .  Amines. Classification of chemical reactions.

https://pt.slideshare.net/antonio.delgado/tema-19-session1 Free radicals, nucleophiles, electrophiles

 Free radicals are that have an unpaired (alone) . This makes them very unstable, and they rapidly combine with other species that are trying to gain a electron. Examples of free radicals

 Nucleophiles can donates a pair of 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 of single-bonded and and lack any Formula other functional groups. 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 C4H10 CH3(CH2)2CH3 reactive species containing only and . C5H12 CH3(CH2)3CH3

The names of all alkanes end with -ane. Whether or not the 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 .  Alkanes can be burned, destroying the entire .  Alkanes can react with some of the , 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 . 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 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 . 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 in the presence of catalysts:

C2H4 + 1/2 O2 → C2H4O  Polymerization Polymerization of alkenes is a reaction that yields 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 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‐ 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 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 . 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 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 (-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 hydroxy groups at different carbon atoms of Alcohol Name Name Formula are called diols (2 HO groups), triols (3 HO groups) and so on (polyhydroxylic alcohols). CH3OH — methyl alcohol methanol

CH3CH2OH primary ethyl alcohol CH CH CH 3 2 primary propyl alcohol 1-propanol 2OH (CH ) CHO isopropyl alcoh 3 2 secondary 2-propanol H ol CH CH CH 3 2 primary butyl alcohol 1-butanol 2CH2OH glycerol CH CH CH sec- (component of triacylglycerols, xylitol 3 2 secondary 2-butanol butyl alcohol OHCH3 glycrophospholipids) (CH ) CHC 2-methyl-1- 3 2 primary isobutyl alcohol H2OH propanol Reactions of alcohols  Oxidation  Alcohols may be oxidized to give ketones, aldehydes, and carboxylic acids.

 The alcohols are toxic if taken in large enough quantities. Although ethanol is less toxic than methanol, it is nonetheless a poisonous substance. When someone is suffering from mild ethanol poisoning, the person is said to be intoxicated. The body has mechanisms of ethanol detoxification. One way the body detoxifies ethanol is to oxidize it, using an enzyme produced by the liver, alcohol dehydrogenase, or ADH. Alcohol dehydrogenase catalyzes the oxidation of ethanol to acetaldehyde, which is further oxidized to acetic acid (as the acetate ), a normal metabolite. The actual oxidizing agent is the oxidized form of nicotinamide adenine dinucleotide, NAD+. The body’s response to simple alcohols is to oxidize them. This strategy works well with ethanol, because the product is acetate, a normal metabolite. When other alcohols are ingested, however, oxidation may lead to other toxic products. For example, oxidation of methanol produces formaldehyde and subsequently formic acid (as the formate ion); both of these products are more toxic than methanol itself.

https://www.britannica.com/science/alcohol/Reactions-of-alcohols Reactions of alcohols

Esterification  Alcohols can combine with many kinds of acids to form esters. When no type of acid is specified, the word ester is assumed to mean a carboxylic ester, the ester of an alcohol and a carboxylic acid. The reaction, called Fischer esterification, is characterized by the combining of an alcohol and an acid (with acid ) to yield an ester plus water.

https://www.chemistrysteps.com/fischer-esterification/ Reactions of alcohols

 Dehydration Alcohol undergoes dehydration in the presence of a catalyst to form an alkene and water. The reaction removes the OH group from the alcohol carbon atom and a hydrogen atom from an adjacent carbon atom in the same molecule: Reactions of alcohols

https://chem.libretexts.org/Bookshelves/Introductory_Chemistry/Book%3A_The_Basics_of_GOB_Chemistry_(Ball_et_al.)/1 4%3A_Organic_Compounds_of_Oxygen/14.05%3A_Reactions_of_Alcohols Hydroxyl compounds: phenols.

 Phenols are compounds in which an OH group is attached directly to an aromatic ring.  Phenol is an aromatic with the molecular formula C H OH.  Phenol is a common name for the compound. Its IUPAC 6 5 name would be benzenol, derived in the same manner as the IUPAC names for aliphatic alcohols.  When a phenol molecule is substituted with additional groups, either the ortho, meta, para system or the numbering system can be employed.  Phenols are widely used as antiseptics and as disinfectants. The first widely used antiseptic was phenol. Joseph Lister used it for antiseptic surgery in 1867. Phenol is toxic to humans, however, and  Phenol exhibits keto-enol tautomerism with its unstable can cause severe burns when applied to the skin. In the bloodstream, keto tautomer cyclohexadienone, but only a tiny fraction it is a systemic poison—that is, one that is carried to and affects of phenol exists as the keto form. all parts of the body.

enol form keto form

https://en.wikipedia.org/wiki/Phenol Reactions of phenol

 Phenol is highly reactive toward electrophilic  Phenol bromination: aromatic substitution as the oxygen atom's pi electrons donate electron density into the ring. By Phenol reacts with bromine water to give white ppt of this general approach, many groups can be appended 2,4,6-tribromophenol. to the ring, via halogenation, acylation, sulfonation, and other processes.  However, phenol's ring is so strongly activated— second only to aniline—that bromination or chlorination of phenol leads to substitution on all carbon atoms ortho and para to the , not only on one carbon.  Phenol :

 Water solutions of phenol are weakly acidic and turn Phenol reacts with conc. HNO3 to form 2,4,6- blue litmus slightly to red. Phenol is neutralized by trinitrophenol. sodium hydroxide forming sodium phenate or phenolate, but being weaker than carbonic acid, it cannot be neutralized by sodium bicarbonate or sodium carbonate to liberate carbon dioxide.

https://byjus.com/chemistry/phenol-electrophilic-substitution/ Amines.

 Amines are derivatives of in which one or - Amines are involved in the structure of amino acids. more of the hydrogens has been replaced by an alkyl - Serotonin, dopamine, norepinephrine are important amines that or aryl group. In amines, one or more of the H atoms functions as one of the neurotransmitters for the brain. - Medicines based on amines such as Morphine and Demerol are in NH3 is substituted with an organic group. commonly used as analgesics – medicines that relieve pain.  A primary amine has one H atom substituted with an R - Amines such as Novocaine are commonly used as anesthetics. The group: amine Ephedra is a common decongestant. Tetramethyl ammonium iodide is used in the disinfection of drinking water.

 A secondary amine has two H atoms substituted with an R group:

 A tertiary amine has all three H atoms substituted with R groups:

https://byjus.com/chemistry/amines/ https://pressbooks.bccampus.ca/chem1114langaracollege/chapter/20-4- amines-and-amides/ Reactions of amines

 The of amines is similar to ammonia: amines are basic, nucleophilic, and react with alkyl halides, acid chlorides, and carbonyl compounds. Additionally, aromatic amines are highly reactive in electrophilic aromatic substitution.  he important organic reactions of amines (nucleophiles) are with thecommon electrophiles :  alkyl halides via nucleophilic substitution  aldehydes or ketones via nucleophilic addition  carboxylic acid derivatives, especially acid chlorides or anhydrides, vianucleophilic acyl http://www.chem.ucalgary.ca/courses/351/Carey5th/Ch22/ch22-3- substitution. 0.html Sources of information

 https://pt.slideshare.net/antonio.delgado/tema-19-session1

 https://esomake.co.ke/secondary/chemistry/organic-chemistry-I-alkynes-form-three

 https://slideplayer.com/slide/9736825/

 https://esomake.co.ke/secondary/chemistry/organic-chemistry-I-alkynes-form-three/

 https://classnotes.org.in/class11/chemistry/hydrocarbons/arenes/

 https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Supplemental_Modules_(Organic_Chemistry)/Arenes/Nomenclature_of_Arenes

 http://www.4college.co.uk/a/Cd/react.php

 https://www.britannica.com/science/alcohol/Reactions-of-alcohols

 https://www.chemistrysteps.com/fischer-esterification/

 https://chem.libretexts.org/Bookshelves/Introductory_Chemistry/Book%3A_The_Basics_of_GOB_Chemistry_(Ball_et_al.)/14%3A_Organic_Compounds_of_ Oxygen/14.05%3A_Reactions_of_Alcohols

 https://en.wikipedia.org/wiki/Phenol

 https://byjus.com/chemistry/phenol-electrophilic-substitution/

 https://pressbooks.bccampus.ca/chem1114langaracollege/chapter/20-4-amines-and-amides/

 http://www.chem.ucalgary.ca/courses/351/Carey5th/Ch22/ch22-3-0.html

 https://byjus.com/chemistry/amines/  Biological and . In 2 books. Book 1. Bioorganic Chemistry. Textbook/B.S.Zimenkovsky, I.V. Nizhenkovska et.al.; edited by B.S.Zimenkovsky, I.V.Nizhenkovska. – Kyiv:AUS Medicine Publishing, 2020.- 288 p.  Semyonova T.V. Bioorganic chemistry: Manual /Semyonova T.V. – Simferopol, 2004. –128p.  Jelena Dodonova. Bioorganic chemistry (Set of lectures)/ Jelena Dodonova. - Vilnius, 2016.-301 p.