2. INTRODUCTION TO ORGANIC CHEMISTRY; SATURATED HYDROCARBONS

3. Organic Chemistry – science that deal generally with compounds of carbon –fats, proteins, carbohydrates –fabrics –wood and paper products –plastics –medicinals

4. Carbon atom is central to all organic compounds What makes carbon special?  unique ability to bond to itself in long chains and rings;  ability to form strong covalent bonds with a variety of elements (H, O, N, S, P, halogens)

5. Carbon atom: C  atomic number 6  electron structure 1s 2 2s 2 2p 2  stable isotopes 12 C and 13 C  carbon has several radioactive isotope

6. Carbon has four valence electrons 1s 2, 2s 2, 2p 2 C

7. C Carbon forms four single covalent bonds by sharing electrons with other atoms. H H HH

8. C H H HH

9. A pair of electrons can be shared between two carbon atoms. One covalent bond can be formed between two carbon atoms. single bond CC

10. Single covalent bond can be formed between two carbon atoms CC single bond A dash represents a covalent bond.

11. Two covalent bonds can be formed between two carbon atoms. double bond C C

12. Two covalent bonds can be formed between two carbon atoms. CC double bond

13. Three covalent bonds can be formed between two carbon atoms. triple bond CC

14. Three covalent bonds can be formed between two carbon atoms. CC triple bond

15. Organic compounds Saturated (only single bonds) Unsaturated (double or triple bonds)

16. The types of molecular formulas and molecular models H H H H C...... C H HH H structural formula C2H6C2H6 CH 4 Lewis formula molecular formula CH 3 condensed structural formula

17. CLASSES OF ORGANIC COMPOUNDS

18. CLASSES OF ORGANIC COMPOUNDS (cont.)

19. HYDROCARBONS compounds that are composed only of carbon and hydrogen atoms bonded to each other by covalent bonds Sources: fossil fuels - natural gas, petroleum, coal Hydrocarbons Aromatic (contain the benzene ring) Aliphatic (open-chain and cyclic) AlkanesAlkenesAlkynes Cycloalkanes Cycloalkenes UNSATURATED SATURATED

20. ALKANES (paraffins, saturated hydrocarbons) straight or branched-chain hydrocarbons with only single covalent bonds between the carbon atoms Homologous series – each member of a series differs from the next member by a CH 2 group. General formula (for open chain alkanes): C n H 2n+2 ; n – number of carbon atoms in the molecule

21. ISOMERISM Isomerism – phenomenon of two or more compounds to have the same molecular formula but different structural arrangement Isomers – compounds that have the same molecular formula but different structural formulas

22. line structure form of methane CH 4 space filling form of methane There is 1 possible structure for CH 4. 19.4

23. CH 3 line structure form of ethane space filling form of ethane There is 1 possible structure for C 2 H 6. 19.4

24. line structure form of propane space filling form of propane CH 3 CH 2 CH 3 There is 1 possible structure for C 3 H 8. 19.4

25. line structure form of butane CH 3 CH 2 CH 2 CH 3 space filling form of butane There are 2 possible structures for C 4 H 10 unbranched chain 19.4

26. line structure form of 2-methyl propane CH 2 CHCH 3 CH 3 branched chain space filling form of 2-methyl propane branched chain There are 2 possible structures for C 4 H 10. 19.4

27. normal butane (n-butane) C 4 H 10 2 –methyl propane C 4 H 10 m.p. –138.3 o C b.p. 0.5 o C m.p. –159.5 o C b.p. – -11.7 o C Normal butane and 2-methyl propane are isomers. Isomers are compounds with the same molecular formula but different structural formulas.

28. Pentane (C 5 H 12 ) has 3 isomers. This is the carbon skeleton with the longest continuous carbon chain. It is the first isomer of pentane. n-pentane Hydrogen is added to each carbon to form four bonds.

29. Pentane (C 5 H 12 ) has 3 isomers. 2-methylpentane To form the next isomer write a four carbon chain. Add the fifth carbon atom to either of the middle carbon atoms. Hydrogen is added to each carbon to form four bonds.

30. Pentane (C 5 H 12 ) has 3 isomers. 2,2-dimethylpropane To form the third isomer write a 3 carbon chain. Add the remaining two carbon atoms to the central carbon atom. Hydrogen is added to each carbon to form four bonds.

31. SATURATED HYDROCARBONS

32. NAMING ORGANIC COMPOUNDS Used to: trivial names Examples: wood alcohol – methanol; marsh gas – methane; alcohol or grain alcohol – ethanol; etc. Now: internationally accepted and systematic method - IUPAC system (International Union of Pure and Applied Chemistry) - established in 1892

33. ALKANES (C n H 2n+2 )ALKYL GROUPS (C n H 2n+1 ) Alkyl Groups Alkyl group - derivative of corresponding alkane The general formula: R = C n H 2n+1. R – any alkyl group. Alkyl group has 1 hydrogen atom less than the corresponding alkane.

34. IUPAC RULES FOR NAMING ALKANES 1.The name of the compound consist of the name of the longest chain prefixed by the names of attached alkyl groups. 2.Select the longest chain. 3.Consider all alkyl groups attached to it. 4.Number the carbon atoms in the carbon chain starting from the end closest to the first carbon atom that has attached alkyl group. 5.Name each branch-chain alkyl group and designate its position by a number (3-methyl means a methyl group attached to carbon 3) 4. If the same alkyl groups occur more than once, indicate this by prefix (di-, tri-, tetra etc) (dimethyl indicates two methyl groups). The numbers indicating the positions of these alkyl groups are separated by comma, followed by a hyphen, and placed in front of the name (2,3-dimethyl). 5. When several alkyl groups are attached to the parent compound, list them in alphabetical order.

35. 1.Select the longest chain. 2.Consider all alkyl groups attached to it. 3.Number the carbon atoms in the carbon chain starting from the end closest to the first carbon atom that has attached alkyl group. 4.Name each branch-chain alkyl group and designate its position by a number (2-methyl means a methyl group attached to carbon 2) Name the following compound 2-methylbutane

36. Name the following compound 2-methylpentane Each of the following formulas represent the same compound – 2- methypentane

37. Name the following compound 2,3-dimethylbuthane 1.Select the longest chain. 2.Consider all alkyl groups attached to it. 3.Number the carbon atoms in the carbon chain starting from the end closest to the first carbon atom that has attached alkyl group. 4.Name each branch-chain alkyl group and designate its position by a number 5.If the same alkyl groups occur more than once, indicate this by prefix (di-, tri-, tetra etc) (dimethyl indicates two methyl groups). The numbers indicating the positions of these alkyl groups are separated by comma, followed by a hyphen, and placed in front of the name (2,3- dimethyl).

38. Name the following compounds 2,2-dimethylbutane 2,4-dimethylhexane H3H3 3-methylhexane

39. Name the following compound 3-chloro- 4-ethyl-2,4- dimethyloctane 1.Select the longest chain. 2.Consider all alkyl groups attached to it. 3.Number the carbon atoms in the carbon chain starting from the end closest to the first carbon atom that has attached alkyl group. 4.Name each branch-chain alkyl group and designate its position by a number (3-methyl means a methyl group attached to carbon 3) 4. If the same alkyl groups occur more than once, indicate this by prefix (di-, tri-, tetra etc) (dimethyl indicates two methyl groups). The numbers indicating the positions of these alkyl groups are separated by comma, followed by a hyphen, and placed in front of the name (2,3- dimethyl). 5. When several alkyl groups are attached to the parent compound, list them in alphabetical order.

40. 2,2,4-trimethylpentane 2-methylhexane 5-ethyl-3-methyloctane Name the following compounds

41. 3,4-dimethylhexane 3-chloro-2,5,5-trimethylheptane 3,3,6-trimethyloctane

42. Write the formula for: 3-ethylpentane 3-bromo-5,6- diethyl-2,7- dimethyl-5- propylnonane

43. Reactions of Carbon 1. Oxidation-reduction reactions Oxidation of carbon compound Reduction of carbon compound

44. 2. Substitution reaction If in a reaction one atom in a molecule is exchanged by another atom or group of atoms 3. Elimination reaction If a single reactant is split into two product, and one of the products is eliminated. Multiple bonds are formed

45. 4. Addition reaction Two reactants adding together to form a single product. Reverse of an elimination reaction

46. Categorize each reaction addition substitution elimination

47. Reactions of alkanes 1. Combustion (with the production of large amount of heat energy) Mechanical energy Electrical energy Combustion reactions are the most important for economics. Combustion reactions are the most active reactions of alkanes. In all other reactions alkanes are sluggish and demand activation (high temperature, catalists) CH 4 (gas) + O 2 (gas)CO 2 (gas) + 2H 2 O + 191,8 kcal thermal energy

48. 2. Halogenation (a substitution reaction) A halogen (Cl or Br) is substituted for a hydrogen atom in halogenation reactions. CH 3 CH 3 + Br 2 CH 3 CH 2 Br + HBr bromoethane CH 3 CH 3 + Cl 2 CH 3 CH 2 Cl + HCl chloroethane Alkylhalides are useful as intermediates for manufacturing of other substances

49. 3. Dehydrogenation (an elimination reactions) Alkanes lose hydrogen during dehydrogenation 4. Cracking Breaking up large molecules to form smaller ones C 16 H 34 C 8 H 18 + C 8 H 16  alkane alkene propane propene CH 3 CH 2 CH 3 CH 3 CH CH 2  + H 2 Alkenes are formed (useful chemical intermediates)

50. 4. Isomerization (rearrangment of molecular structure) CH 3 CH 2 CH 2 CH 2 CH 3 CH 3 CH 2 CHCH 3 CH 3 catalist , pressure Halogenation reaction is used for production of petrochemicals (chemicals derived from petroleum and used for other purposes than fuel) Dehydrogenation, cracking and isomerization reactions are used for production of motor fuels.

51. Alkyl halides formation CH 4 + Cl 2 CH 3 Cl + HCl chloromethane Reaction of methane with chlorine gives the mixture of mono-, di-, tri-, and tetrasubstituted chloromethanes CH 4 CH 3 Cl CH 2 Cl 2 CHCl 3 CCl 4 + HCl Cl 2 The more chlorine the more CCl 4. chloro- methane dichloro- methane trichloro- methane tetrachloro- methane Monosubstitution product - one hydrogen atom is substitued by another atom Di-, tri, tetra- and so on substituted compounds – two, three, four hydrogen atom are substitued by another atoms

52. CYCLOALKANES Hydrocarbons Aromatic (contain the benzene ring) Aliphatic (open-chain and cyclic) AlkanesAlkenesAlkynes Cycloalkanes Cycloalkenes Cycloalkanes (cycloparaffins, naphthenes) – cyclic, or close-chain, alkanes. Cycloalkanes are saturated hydrocarbons. General formula – C n H 2n (two fewer hydrogen atoms than the corresponding open chain alkane)

53. Add prefix cyclo to the name of alkane with the same number of carbon atom Naming of Cycloalkanes

54. UNSATURATED HYDROCARBONS

55. Widely used: polymers (plastic things); in medicine, cosmetics, perfumes, flavorings; detergents, insecticides, dyes. Hydrocarbons Aromatic (contain the benzene ring) Aliphatic (open-chain and cyclic) AlkanesAlkenesAlkynes Cycloalkanes Cycloalkenes Alkenes – double bond Alkynes – triple bond Aromatic – benzene ring

56. Nomenclature of alkenes 1.Select the longest carbon-carbon chain containing the double bond 2.Name this compound as you would an alkane but change the –ane ending to –ene. Example: propane is changing to propene. 3.Number the carbon chain of compound starting with the end nearer to the double bound. 4.Place the number indicating the location of double bond in front of the alkene name (example: 3- propene) 5.Branch chains and other groups are treated as for alkanes.

57. 1-butene 2-butene 3-methyl-1-butene 3-propyl-1-hexene Name the following compounds

58. Write a structural formula for: 4-methyl-2-pentene 7-methyl-2-octene

59. IMPORTANT: in naming of alkenes the double bond must be included in the chain even if there is longer chain in this compound the longest carbon chain contains six carbons We must include the double bond in the chain the carbon chain containing the double bond has five carbons 2-ethyl-1-pentene

60. Name the following compounds 3-methyl-2-pentene2,4-dimethyl-2-pentene 2-methyl-1-butene 2-methyl-2-butene

61. Name the following compounds 3-methyl-3-heptene 3-methyl-1-heptene 3-ethyl-3-methyl- 1-heptene

62. Write a structural formula for: 4-chloro-5,6- diethyl-2,7- dimethyl-5- propyl-2-nonene 4,5-dichloro- 2,3-dimethyl- 1-pentene

63. Nomenclature of alkenes containing more than one double bond Compounds with two (di) double bounds are called dienes, with three (tri) – trienes. 1,4-pentadiene 2-methyl-1,3-butadiene Name the following compounds

64. 4,5-dichloro-3-methyl- 1,2,4-pentatriene 5-methyl-4-pentyl- 2,5-octadiene

65. Geometric Isomerism in Alkenes 1,2-dichloroethane carbon atoms can rotate freely about the single bond these two compounds are identical carbon atom can not rotate about the double bond Restricted rotation of carbon atom around the bond with other carbon atom results in the phenomenon known as geometric isomerism

66. these compounds are different cis-1,2- dichlorethene trans-1,2- dichlorethene Geometric isomers (cis- trans isomers) - compounds that differ from each other only in the geometry of their molecules and not in the order of their atoms Cis- isomer has substituent groups on the same side of the double bond Trans- isomer has substituent groups on the opposite sides of the double bond

67. An alkene shows cis-trans isomerism when each carbon atom of the double bond has two different kinds of groups attached to it cis-isomer trans-isomer An alkene doesn’t show cis-trans isomerism if one carbon atom of the double bond has two identical groups attached to it

68. cis-2-butenetrans-2-butene Write geometric isomers for: 2-butene

69. Chemical properties of alkenes Addition So far as alkenes have double bonds they are more reactive than alkanes and undergo addition reactions. Some of the reagents that can be added to alkenes: hydrogen, halogens, hydrogen halides, water, sulfuric acid, etc. C C Brown color of Br 2 disappears in this reaction.

70. As result of addition alkenes are converted to saturated molecules. Addition reactions are reverse to the elimination reactions.

71. Markovnikov’s rule When an asymmetrical molecule HX (HCl) adds to a carbon-carbon double bond, the hydrogen from HX goes to the carbon atom that has the greater number of hydrogen atoms.

72. Write the formulas for the organic compounds formed when 2-methyl-1-butene reacts with (a) H 2, (b) Cl 2, (c) HCl, (d) H 2 O 2-methyl- 1-butene (a) (b) 1,2-dichloro-2- methylbutane (c) (d)

73. Hydrocarbons Aromatic (contain the benzene ring) Aliphatic (open-chain and cyclic) AlkanesAlkenesAlkynes Cycloalkanes Cycloalkenes Widely used: plastic things; in medicine, cosmetics, perfumes Alkynes – unsaturated hydrocarbons containing triple bond Alkynes

74. Naming of alkynes 1.Select the longest carbon-carbon chain containing the triple bond. 2.Name this compound as for alkene but change the –ene ending to –yne. 3.Number the carbon chain of compound starting with the end nearer to the triple bound. 4.Place the number indicating the location of triple bond in front of the alkyne name (example: 3-propyne) 5.Branch chains and other groups are treated as for alkanes.

75. Chemical properties Addition Reactions Positive Bayer’s test with potassium permanganate (disappearance of purple-pink color) Reactions with halogens. Either one or two molecules of halogens can be added.

76. Reactions with hydrogen halides. Vinyl chloride is widely used in chemical industry, for example for production of plastic polyvinyl chloride This reaction follows Markovnikov’s rule.

77. These reactions follow Markovnikov’s rule. Acetylene is the most important industrially. Many different polymers are manufactured from acetylene (production of clothes, superabsorbents (disposable diapers, soil additives))

78. Aromatic hydrocarbons Structure Benzene and its derivatives are classified as aromatic hydrocarbons. Kekule’s formula: carbon atoms in a benzene molecule are arranged in a six-membered ring with one hydrogen atom bonded to each carbon atom and with three double carbon-carbon bonds. Molecular formula of benzene: C 6 H 6 Benzene doesn’t react as a typical alkene (doesn’t decolorize bromine solution, negative Bayer’s test). Benzene behaves chemically like a typical alkane (substitution reactions).

79. Structure of benzene can be represent by different formulas Kekule structures Kekule formulas are classical however such structures actually doesn’t exist Formulas C or D more accurately represent the real benzene structure

80. Naming of aromatic compounds Monosubstituted benzenes 1.Add the name of a substitutent group as a prefix to the word benzene 2.Write the name as one word 3.Position of substituent is not important

81. Name the following compounds: fluorobenzene propylbenzene ethylbenzene hydroxybenzene

82. Some monosubstituted benzenes have special (trivial) names. These names should be memorize.

83. The group (C 6 H 5 ) is called phenyl group The name phenyl can be used to name compounds that can not easily be named as benzene derivatives 3-chloro-2-phenylpentanediphenylmethane

84. Disubstituted Benzenes In disubstituted benzenes the prefixes ortho-, meta- and para- (o-, m-, p-) are used for naming. In ortho- disubstituted compounds, the two substituents are located on adjacent carbon atoms In meta- disubstituted compounds, the two substituents are one carbon apart In para- disubstituted compounds, the two substituents are located on opposite points of ring

85. ortho-dichlorobenzene Name the following compounds: meta-dichlorobenzenepara-dichlorobenzene ortho-diethylbenzene meta-diethylbenzene para-diethylbenzene

86. When the two substituents are different the names of two substituents are given in alphabetical order o-bromochlorobenzenem-ethylnitrobenzene p-ethylmethylbenzene o-butylethylbenzene

87. Sources and using of aromatic hydrocarbons Sources:  Coal tar (by-product of the manufacture of coke)  Alkanes found in petroleum Using: in the production of - drugs, - dyes, - detergents, - explosives, - insecticides, - plastics, - synthetic rubber.

88. ALCOHOLS

89. Alcohols – a class of compounds containing the hydroxyl (-OH) functional group General formula – ROH Alcohols are derived from aliphatic hydrocarbons by the replacement of at least one hydrogen atom with a hydroxyl group

90. Classification of Alcohols  Primary – carbon atom to which the –OH group is attached is directly bonded to one other carbon atom  Secondary – carbon atom to which the –OH group is attached is directly bonded to two other carbon atom  Tertiary – carbon atom to which the –OH group is attached is directly bonded to three other carbon atom

91. If two or more –OH groups are attached to the same carbon atom such compound is not stable If two or more –OH groups are attached to the different carbon atoms such compounds is stable polyhydroxy alcohols  monohydroxy-,  dihydroxy-,  trihydroxy-,  tetrahydroxy-, and so on. Alcohols can be also classified as

92. The formulas of alcohol can be written as follow: or 2-butanol

93. Naming of alcohols 1.Select the longest chain of carbon atoms containing the hydroxyl groups 2.Number the carbon atoms in this chain so that the one bearing the –OH group has the lowest possible number 3.Form the parent alcohol name by replacing the final –e of alkane by –ol. 4.Locate the position of the –OH by placing the number of corresponding carbon atom before the alcohol name. 5.Name each side chain and designate its position by number

94. Name the alcohol CH 3 CH 2 CH 2 CH 2 OH 1. The longest carbon chain has 4 carbons 2. Number the carbon atoms (carbon bonded to –OH must have number 1) 3. Four carbon alkane is called butane. Change –e to –ol butanol 4. OH group is on carbon 1, so place 1 before butanol Result: 1-butanol

95. Name the following compounds 1-propanol 2-propanol cyclohexanol 3-methyl-1-butanol 4-methyl-2-hexanol 2-ethyl-1-pentanol 5-bromo-5-methyl-3-hexanol 3-methylcyclopentanol

96. Write the structural formulas for: 3,3-dimethyl-2-hexanol 2-chloro-4-methylcyclopentanol 4-phenyl-2-butanol2,3,4-trichlorocyclobutanol

97. Nomenclature of alkohols containing more than one -OH groups Compounds with two (di) –OH groups are called diols, with three (tri) – triols. Name the following compounds 1,3-cyclohexanediol 1,2-ethanediol 1,2,3-propanetriol 2,5-dimethyl-1,3,4-heptanetriol

98.  relatively high boiling point (depends on the hydrogen bonding between alcohol molecules)  alcohols containing up to three carbon atom are soluble in water (solubility depends on hydrogen bonding between alcohol molecules and water)  alcohols with 5-11 carbons are oily liquids, 12 or more carbon atoms – waxlike solids  two or more –OH groups increase boiling point and solubility Alcohols:

99. Chemical properties of alcohols Acidic and basis properties (similar to water properties) a) In acidic solution alcohols accept a proton oxonium ion (protonated alcohol) b) Alcohols react with alkali metals to release hydrogen alkoxide ion (strong base)

100. 1. Oxidation The hydroxyl group gives an alcohol the capability of forming an aldehide, ketone or carboxylic acid Tertiary alcohols don’t have a hydrogen on the – OH carbon and can not react with oxidizing agents Oxidation occurs at the carbon atom bonded to the –OH group and this atom becomes an aldehyde or carboxylic acid. The rest of the molecule remains the same.

101. Oxidation of ethanol in organism (in liver) Toxic compound, can cause the liver damage (liver cirrhosis) Can be used as sourse of energy for the organism

102. 2. Dehydration (elimination of water) a. Intramolecular dehydration (the alkenes are formed) Saytzeff’s rule. If there is the choice of positions for double bond the preferred location is the one that gives the more highly substituted alkene – that is, the alkene with the most alkyl groups attached to double-bond carbons. Remove the hydrogen from the carbon with fewer hydrogen.

103. b. Intermolecular dehydration (the ethers are formed) This type of reaction occurs only between primary alcohols. Such type of reactions is called condensation reaction (two molecules are combined with removing of small molecule).

104. 3. Esterification (convertion of alcohols to esters) Alcohol reacts with carboxylic acid to form an ester and water.

105. Utility of the Hydroxyl Group

106. Common Alcohols Methanol (wood alcohol) Preparation: - heating of wood to high temperature without oxygen (distructive distillation) - hydrogenation of carbon monoxide under the high pressure methanol Physical properties:  highly flammable liquid  poisonous, can cause blindness and death Using: -convertion to formaldehyde –manufacture of esters and other chemicals –production of denaturing ethyl alcohol -industrial solvent

107. Ethanol (ethyl alcohol, spirit) Preparation: -fermentation. Starch is converted to sugar, then sugar is converted to ethanol. The enzymes of yeast are used. -acid-catalyzed addition of water to ethylene (ethylene can be obtain from petroleum) Using: -intermediate in the production of other chemicals -solvent for many organic substances -ingredient for pharmaceutical, perfumes, flavorings -ingredient of alcoholic beverages

108. Glycerol (1,2,3-propanetriol, glycerine) Contains three –OH groups. Physical properties: -liquid with a sweet, warm taste -hygroscopic (is able to hold water molecules by hydrogen bonding) Preparation: -by-product of processing fats to make soap and other products -it is synthesized from propene Using: -manufacturing of polymers -manufacturing of explosives -emollient in cosmetics

109. ETHERS General formula R-O-R’. R and R’ can be saturated, unsaturated or aromatic hydrocarbons. R and R’ can be alike or different. Naming ethers A. Common names (only for naming simple ethers) Common names are formed from the names of groups attached to oxygen atom

110. Name the following compounds using common names diethyl ether; ethyl ether or ether CH 3 CH 2 -O-CH 2 CH 3 diphenyl ether methyl phenyl ether butyl propyl ether ethyl isopropyl ether divinyl ether

111. B. Naming according to IUPAC system Alkoxy group is named by dropping the ending –yl of the alkyl name and adding the suffix –oxy. Examples: CH 3 O-, alkyl is called methyl, replace ending –yl to –oxy. Group is called methoxy. CH 3 CH 2 O- - is called ethoxy (eth + oxy). - is called phenoxy (phen + oxy). Group R-O- is called alkoxy group (consist of alkyl group R- and oxygen atom).

112. Rules for naming ethers 1.Select the longest carbon chain and label it with the name of corresponding alkane. 2.Change the –yl ending of other hydrocarbon group to –oxy. 3.Combine the two names giving the alkoxy name and its position on the longest carbon chain first. metoxyethane

113. CH 3 CH 2 -O-CH 2 CH 3 Name the following compounds ethoxyethane methoxybenzene phenoxybenzene 1-propoxybutane 2-propoxybutane 2-ethoxypropane 3-butoxypentane

114. Name the following compounds 1-methoxy-2-methylpropane m-chloromethoxybenzene 1,2-dichloro-4- propoxybenzene 2-isopropoxy-4- methylpentane

115. Physical Properties of Ethers The shape of molecule is similar to water and alcohol molecules Ethers are more polar than alkanes (alkanes don’t conatain oxygen atom) Ethers are less polar than alcohols or water (ethers don’t contain hydrogen) Ethers form hydrogen bonds with water molecules or acids

116.  Ethers – very good solvents for organic compounds  Some polar compounds (water, alcohols) can be dissolve to some extent in ethers  Ethers are highly flammable  Vapors can form with air explosive mixture  Ethers with long carbon chain are insoluble in water  Ethers with small carbon chain are very little soluble in water and acids  Solubility and boiling point of ethers depend on the carbon chain structure

117.  Ethers have little chemical reactivity  Ethers can slowly react with oxygen from air to form peroxides (explosive substances). Chemical Properties

118. Preparation of ethers 1. Intermolecular dehydration of alcohols 2. Williamson synthesis. Alkyl halides react with sodium alkoxides or sodium phenoxides to form ethers. This is the substitution reaction.

119. Thiols Thiols (mercaptants) – organic compounds containing –SH group. Naming of thiols The principle of naming is as for alcohols but except the ending –ol the ending –thiol is used. methanethiol 2-butanethiol 4-methyl-3- hexanethiol cyclohexanethiol

120. Properties 1.Foul odours (natural gas is odorized by methanethiol to be detectable) 2.Oxidation to disulfides Functions  Disulfide structures in proteins.  Constituent of coenzyme A (metabolism).

121. ALDEHYDES AND KETONES

122. Structure of aldehydes and ketones CO Both aldehydes and ketones contain carbonyl group Differerence: -aldehydes contain hydrogen atom bounded to carbonyl group -ketones have only alkyl or aromatic groups attached to carbonyl group

123. Methanal is the smallest aldehyde (the first member from the homologous series) Ethanal is the second member of the homologous series methyl group on 4 carbon the longest chain is hexane 4-methylhexanal

124. Name the following compound pentanal 5-chloro-4-methylpentanal 3,5-dihydroxyhexanal 3-phenyl-2-propenal 2-methyl-3-phenylpentanal

125. Naming of Ketones 1.Select the longest chain containing the ketone group. 2.Drop the ending –e from the corresponding alkane name and add the suffix –one. 3.If the chain is longer than four carbons, it is numbered so that the carbonyl group has the lowest number possible. This number is prefixed to the parent name of the ketone. 4.Name other groups attached to parent chain as usual.

126. Name the following compounds propanonebutanone2-pentanone 4-methyl-3-hexenone 4-hydroxy- 3-methyl-2- pentanone cyclohexanone2,4,6- trimethylcyclohexanone 1-hydroxy-5-phenyl- 2-pentanone

127. Alternative Names of Ketones It is used to name simple ketones. List the names of the alkyl or aromatic groups attached to carbonyl carbon together with the word ketone. methyl ethyl ketone (butanone) methyl methyl ketone (propanone) Propanone and butanone are the most widely used ketones. They have the special (common) names: acetone (propanone) and MEK (butanone).

128. Name the following compounds ethyl ethyl ketone (diethyl ketone) ethyl isopropyl ketone dicyclohexyl ketone diisopropyl ketone

129. Naming of Aromatic Ketones Aromatic ketones are named similarly to the aliphatic ketones and can have the special names as well. 1-phenylethanone (methyl phenyl ketone) 1-phenyl-1-propanone (ethyl phenyl ketone) 2-methyl-1-phenyl- 1-butanone

130. Cinnamaldehyde (oil of cinamon) Benzaldehyde (oil of bitter almonds) Naturally occurring aldehydes and ketones Many aldehydes have a specific odour and can be used in flavoring and perfumes

131. Carvone (chief component of spearmint oil) Muscone (gland of male musk deer, used in perfumes)

132. Civetone (secretion of the civet cat, used in perfumes) Camphor (from the camphor tree)

133. Cortisone (hormone; produced by epinephrine glands; regulate metabolism in organism; widely used in medicine) Glucose RiboseFructose Sugars; energetic and plastic material for organism

134. Citral (oil of lemon) Vitamin K (antihemorrhagic vitamin)

135. Chemical Properties of Aldehydes and Ketones CO Chemical properties of aldehydes and ketones are determined by the functional carbonyl group 1. Oxidations Aldehydes are oxidized to carboxylic acids by different agents (K 2 Cr 2 O 7 +H 2 SO 4 ; Ag + ; Cu 2+ ; oxygen of air) Ketones are not oxidized by such agents. Ketones can be oxidized under drastic conditions (hot potassium permanganate). Carbon-carbon bonds are broken under these conditions and variety of products are formed. orange green

136. The Tollens test (silver-mirror test) Silver ions oxidizes ammonia (Tollens’ reagent is formed) Ag + ions are reduced to metallic silver by aldehydes Add into tube aldehyde, silver nitrate and ammonia The silver mirror appears on the inner wall of the tube 2 2 H2OH2O Tollens’ Reagent 3

137. Fehling test Fehling solutions contain Cu 2+ ions in alkaline medium. Cu 2+ has blue color. During reaction it is reduced and brick- red copper oxide is formed. Before reaction (blue color of Cu 2+ ) After reaction (brick-red color of Cu 2 O)

138. Ketones don’t give a positive Tollens or Fehling tests Tollens or Fehling test can be used to distinguish between aldehydes and ketones

139. 2. Reduction Aldehydes and ketones are reduced to alcohols Reducing agents: -hydrogen (catalyst Ni); -litium aluminium hydride (LiAlH 4 ); -sodium borohydride (NaBH 4 ). Aldehydes yield primary alcohols; ketones yield secondary alcohols

140. Common Aldehydes and Ketones Formaldehyde (methanal) Can be obtained in the oxidation of methanol by oxygen (silver or copper are catalysts) Properties: -gas -poisonous -very irritating (ingestion can cause death) -soluble in water -37 % solution of formaldehyde is called formalin Using:  manufacture of polymers;  preservation of biological specimens

141. Acetaldehyde (ethanal) Can be obtained in the oxidation of ethanol Volatile liquid with pungent odor Using: intermediate in the production of other chemicals (for example, acetic acid) Three or four molecules of ethanal can polymeraze to form cyclic compounds paraldehyde and metaldehyde, which can be used for production of sedative drugs and pesticides

142. Acetone (methyl methyl ketone) and MEK (methyl ethyl ketone) Using: solvents, manufacturing of drugs, chemicals, explosives, in plastic industry; for removal of paints Acetone and MEK can be obtained by oxidation of secondary alcohols: Acetone is formed in human body In some diseases (diabetes mellitus, starvation) the concentration of acetone is increased in blood and urine.