Alkyne combustion reaction: 2 C 2 H O 2 4 CO H 2 O The combustion reactions are all exothermic. 180

Substitution Reactions 181

Substitution Reactions Reaction with chlorine: 182

Substitution Reactions Reaction with chlorine: CH 4 + Cl 2 CH 3 Cl + HCl chloromethane 183

Substitution Reactions Reaction with chlorine: CH 4 + Cl 2 CH 3 Cl + HCl chloromethane CH 3 Cl + Cl 2 CH 2 Cl 2 + HCl dichloromethane 184

CH 2 Cl 2 + Cl 2 CHCl 3 + HCl trichloromethane 185

CH 2 Cl 2 + Cl 2 CHCl 3 + HCl trichloromethane CHCl 3 + Cl 2 CCl 4 + HCl tetrachloromethane 186

For organic reactions it is common practice to indicate the reaction conditions. That is, for the reaction with chlorine: 187

For organic reactions it is common practice to indicate the reaction conditions. That is, for the reaction with chlorine: CH 4 + Cl 2 CH 3 Cl + HCl 188

For organic reactions it is common practice to indicate the reaction conditions. That is, for the reaction with chlorine: heat (300 o C) CH 4 + Cl 2 CH 3 Cl + HCl 189

For organic reactions it is common practice to indicate the reaction conditions. That is, for the reaction with chlorine: heat (300 o C) CH 4 + Cl 2 CH 3 Cl + HCl or uv irrad. room temp. 190

Addition Reactions 191

dark Cl o C 1,2- dichloroethane 192

CH 3 CCH + 2 Cl 2 CH 3 CCl 2 CHCl 2 propyne 1,1,2,2-tetrachloropropane CH 3 CHCH 2 + HBr CH 3 CHBrCH 3 propene 2-bromopropane It turns out that when a hydrogen halide add to an alkene, the more electronegative halogen atom always tends to end up on the carbon atom of the double bond that has fewer hydrogen atoms (Markovnikov’s rule). 193

H 2 SO 4 CH 2 CH 2 + H 2 O CH 3 CH 2 OH 194

Hydrogenation The following reaction is an example of hydrogenation of an alkene, addition of H 2 across a double bond. 195

+ H 2 ethene ethane 196

Functional Group Concept 197

Functional Group Concept A great many organic molecules have complex structures. 198

Functional Group Concept A great many organic molecules have complex structures. Trying to predict the properties and possible reactions of a complex structure can be very difficult. 199

Functional Group Concept A great many organic molecules have complex structures. Trying to predict the properties and possible reactions of a complex structure can be very difficult. Chemists have found it very useful to characterize certain well defined fragments of an organic molecule. 200

Functional Group Concept A great many organic molecules have complex structures. Trying to predict the properties and possible reactions of a complex structure can be very difficult. Chemists have found it very useful to characterize certain well defined fragments of an organic molecule. These fragments (in isolation) have well defined reactive capabilities. 201

When these units are found in complex structures, predictions can be made as to the likely properties and reactions of the complex structure. 202

When these units are found in complex structures, predictions can be made as to the likely properties and reactions of the complex structure. These fragment units are called functional groups. 203

Some common functional groups Functional Name Example IUPAC Name Common Name group formula 204

Some common functional groups Functional Name Example IUPAC Name Common Name group formula R O H alcohol CH 3 OH methanol methyl alcohol 205

Some common functional groups Functional Name Example IUPAC Name Common Name group formula R O H alcohol CH 3 OH methanol methyl alcohol R C carboxylic CH 3 CO 2 H ethanoic acid acetic acid acid 206

Some common functional groups Functional Name Example IUPAC Name Common Name group formula R O H alcohol CH 3 OH methanol methyl alcohol R C carboxylic CH 3 CO 2 H ethanoic acid acetic acid acid R C ketone CH 3 COCH 3 propanone acetone 207

Some common functional groups Functional Name Example IUPAC Name Common Name group formula R O H alcohol CH 3 OH methanol methyl alcohol R C carboxylic CH 3 CO 2 H ethanoic acid acetic acid acid R C ketone CH 3 COCH 3 propanone acetone R and are alkyl (or more complicated groups). cannot be H. R cannot be H for the alcohol (that would be water!), nor for the ketone (that would give an aldehyde). 208

Functional Name Example IUPAC Name Common Name group formula R C aldehyde HCHO methanal formaldehyde 209

Functional Name Example IUPAC Name Common Name group formula R C aldehyde HCHO methanal formaldehyde R C ester CH 3 CO 2 CH 2 CH 3 ethyl ethanoate ethyl acetate 210

Functional Name Example IUPAC Name Common Name group formula R C aldehyde HCHO methanal formaldehyde R C ester CH 3 CO 2 CH 2 CH 3 ethyl ethanoate ethyl acetate R NH 2 amine CH 3 NH 2 aminomethane methylamine 211

Functional Name Example IUPAC Name Common Name group formula R C aldehyde HCHO methanal formaldehyde R C ester CH 3 CO 2 CH 2 CH 3 ethyl ethanoate ethyl acetate R NH 2 amine CH 3 NH 2 aminomethane methylamine R and are alkyl (or more complicated groups). cannot be H (that would give an acid). R cannot be H for the amine (that would be ammonia!). 212

Functional Name Example IUPAC Name Common Name group formula R O ether CH 3 OCH 3 methoxymethane dimethyl ether 213

Functional Name Example IUPAC Name Common Name group formula R O ether CH 3 OCH 3 methoxymethane dimethyl ether R C amide CH 3 CONH 2 ethanamide 214

Functional Name Example IUPAC Name Common Name group formula R O ether CH 3 OCH 3 methoxymethane dimethyl ether R C amide CH 3 CONH 2 ethanamide R and are alkyl (or more complicated groups). cannot be H (that would give an alcohol). R cannot be H for the ether (that would also give an alcohol). 215

Summary of name endings 216

Summary of name endings Functional group Parent alkane name ending 217

Summary of name endings Functional group Parent alkane name ending alcohol change e to ol 218

Summary of name endings Functional group Parent alkane name ending alcohol change e to ol carboxylic acid change e to oic acid 219

Summary of name endings Functional group Parent alkane name ending alcohol change e to ol carboxylic acid change e to oic acid ketone change e to one 220

Summary of name endings Functional group Parent alkane name ending alcohol change e to ol carboxylic acid change e to oic acid ketone change e to one aldehyde change e to al 221

Summary of name endings Functional group Parent alkane name ending alcohol change e to ol carboxylic acid change e to oic acid ketone change e to one aldehyde change e to al amide change e to amide 222

Summary of name endings Functional group Parent alkane name ending alcohol change e to ol carboxylic acid change e to oic acid ketone change e to one aldehyde change e to al amide change e to amide amine insert amino in front of alkane name 223

Summary of name endings Functional group Parent alkane name ending alcohol change e to ol carboxylic acid change e to oic acid ketone change e to one aldehyde change e to al amide change e to amide amine insert amino in front of alkane name ester insert alkyl name then change e to oate 224

Summary of name endings Functional group Parent alkane name ending alcohol change e to ol carboxylic acid change e to oic acid ketone change e to one aldehyde change e to al amide change e to amide amine insert amino in front of alkane name ester insert alkyl name then change e to oate ether change ane to oxy then add in second alkane name. 225

Key comment on a functional group The carboxylic acid is a combination of two functions groups: O O C C plus O H O H carboxylic acid ketone alcohol 226

Key comment on a functional group The carboxylic acid is a combination of two functions groups: O O C C plus O H O H carboxylic acid ketone alcohol HOWEVER, a compound such as 227

CH 3 CH 2 CCH 2 CH 2 OH O would NOT function like a carboxylic acid, but as an alcohol in some reactions and a ketone in some other reactions. 228

Comparison of some properties 229

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Some simple representative reactions of a few functional groups. 233

Formation of an ester: O O CH 3 C + CH 3 CH 2 OH CH 3 C + H 2 O O H OCH 2 CH 3 carboxylic acid alcohol ester 234

Formation of an ester: O O CH 3 C + CH 3 CH 2 OH CH 3 C + H 2 O O H OCH 2 CH 3 carboxylic acid alcohol ester ethanoic acid ethanol ethyl ethanoate 235

Oxidation of an alcohol: H 2 SO 4,K 2 Cr 2 O 7 CH 3 CH 2 OH alcohol warm 236

Oxidation of an alcohol: H 2 SO 4,K 2 Cr 2 O 7 O CH 3 CH 2 OH CH 3 C alcohol warm H aldehyde 237

Oxidation of an alcohol: H 2 SO 4,K 2 Cr 2 O 7 O CH 3 CH 2 OH CH 3 C alcohol warm H aldehyde further warming O carboxylic acid CH 3 C O H 238

Note: In organic reactions, the side products (e.g. Cr 3+ in the preceding reaction) are often not given. Here is the complete chemical equation: 239

Note: In organic reactions, the side products (e.g. Cr 3+ in the preceding reaction) are often not given. Here is the complete chemical equation: 16 H Cr 2 O CH 3 CH 2 OH 4 Cr 3+ +3CH 3 CO 2 H + 11 H 2 O 240

Note: In organic reactions, the side products (e.g. Cr 3+ in the preceding reaction) are often not given. Here is the complete chemical equation: 16 H Cr 2 O CH 3 CH 2 OH 4 Cr 3+ +3CH 3 CO 2 H + 11 H 2 O (orange) (green) 241

The intermediate reaction would be: 8 H + + Cr 2 O CH 3 CH 2 OH 2 Cr CH 3 CHO + 7 H 2 O (orange) (green) 242

Oxidation of an alcohol: OH H 2 SO 4,K 2 Cr 2 O 7 O CH 3 CHCH 3 CH 3 CCH 3 alcohol or KMnO 4 ketone 243

Aromatic Compounds 244

Aromatic Compounds Aromatic – from aroma – a number of these compounds have strong and sometimes pleasant odors. 245

Aromatic Compounds Aromatic – from aroma – a number of these compounds have strong and sometimes pleasant odors. The most important compound in this family is benzene. 246

Benzene C 6 H 6 This is a very important example in organic chemistry – an example of resonance: C C C C C C C C C C C C 247

The two resonance structures are averaged leading to the following structure: C C C C C C 248

If resonance were not important for benzene, i.e. only one of the two preceding resonance structures were required to describe the structure of benzene, then we might expect benzene to have a reactivity similar to 249

If resonance were not important for benzene, i.e. only one of the two preceding resonance structures were required to describe the structure of benzene, then we might expect benzene to have a reactivity similar to CH 2 CH CH CH CH CH 2 250

If resonance were not important for benzene, i.e. only one of the two preceding resonance structures were required to describe the structure of benzene, then we might expect benzene to have a reactivity similar to CH 2 CH CH CH CH CH 2 1,3,5-hexatriene 251

If resonance were not important for benzene, i.e. only one of the two preceding resonance structures were required to describe the structure of benzene, then we might expect benzene to have a reactivity similar to CH 2 CH CH CH CH CH 2 1,3,5-hexatriene This is not the case! 252

If resonance were not important for benzene, i.e. only one of the two preceding resonance structures were required to describe the structure of benzene, then we might expect benzene to have a reactivity similar to CH 2 CH CH CH CH CH 2 1,3,5-hexatriene This is not the case! 1,3,5-hexatriene is fairly reactive with a variety of reagents (e.g. HBr, Cl 2, etc. in the dark). These reagents react only slowly with benzene. 253

Benzene is more stable than might be expected by examination of the individual resonance structures. 254

Naming benzene compounds 255

Naming benzene compounds chlorobenzene 256

1,2-dibromobenzene 257

1,2-dibromobenzene 1,3-dibromobenzene 258

1,2-dibromobenzene 1,3-dibromobenzene 1,4-dibromobenzene 259

o-dibromobenzene m-dibromobenzene p-dibromobenzene 260

o-dibromobenzene m-dibromobenzene o = ortho m = meta p = para p-dibromobenzene 261

Steroids 262

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IUPAC name (10R, 13R)-10,13-dimethyl-17-(6-methylheptan-2- yl)-2,3,4,7,8,9,11,12,14,15,16,17-dodecahydro-1H- cyclopenta[a]phenanthren-3-ol 265

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269 oral contraceptive

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Theobromine (replace the CH 3 at the arrow by H) is the stimulant found in 272

Theobromine (replace the CH 3 at the arrow by H) is the stimulant found in chocolate. 273

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Stereochemistry 277

Stereochemistry Stereochemistry: Deals with the 3- dimensional arrangement of atoms in space for a particular chemical structure. 278

Stereochemistry Stereochemistry: Deals with the 3- dimensional arrangement of atoms in space for a particular chemical structure. It also deals with how molecules react in 3- dimensions. 279

Isomers 280

Isomers Two or more compounds with the same molecular formulas but different arrangements of the atoms in space. 281

Isomers Two or more compounds with the same molecular formulas but different arrangements of the atoms in space. Three different types of isomerism will be considered. 282

Isomers Two or more compounds with the same molecular formulas but different arrangements of the atoms in space. Three different types of isomerism will be considered. 1. Structural isomers (constitutional isomers) 283

Isomers Two or more compounds with the same molecular formulas but different arrangements of the atoms in space. Three different types of isomerism will be considered. 1. Structural isomers (constitutional isomers) 2. Geometric isomers 284

Isomers Two or more compounds with the same molecular formulas but different arrangements of the atoms in space. Three different types of isomerism will be considered. 1. Structural isomers (constitutional isomers) 2. Geometric isomers 3. Optical isomers 285

Structural isomers 286

Structural isomers Structural isomers (constitutional isomers): Compounds with the same molecular formulas but different arrangements of the atoms. 287

Structural isomers Structural isomers (constitutional isomers): Compounds with the same molecular formulas but different arrangements of the atoms. Example: Draw the structural isomers for C 4 H

CH 3 CH 2 CH 2 CH 3 butane 289

CH 3 CH 2 CH 2 CH 3 butane CH 3 CHCH 3 2-methylpropane CH 3 (the 2 is redundant in this name) 290

Example: Draw the structural isomers for C 5 H

Example: Draw the structural isomers for C 5 H 12 CH 3 CH 2 CH 2 CH 2 CH 3 pentane 292

Example: Draw the structural isomers for C 5 H 12 CH 3 CH 2 CH 2 CH 2 CH 3 pentane CH 3 CH 2 CHCH 3 2-methylbutane CH 3 (2 is redundant) 293

Example: Draw the structural isomers for C 5 H 12 CH 3 CH 2 CH 2 CH 2 CH 3 pentane CH 3 CH 2 CHCH 3 2-methylbutane CH 3 (2 is redundant) CH 3 CH 3 CCH 3 2,2-dimethylpropane CH 3 (each 2 is redundant) 294

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Example: Draw the structural isomers for C 2 H 6 O 297

Example: Draw the structural isomers for C 2 H 6 O CH 3 CH 2 OH ethanol 298

Example: Draw the structural isomers for C 2 H 6 O CH 3 CH 2 OH ethanol CH 3 OCH 3 methoxymethane (dimethyl ether) 299

Exercise: Draw and name all the structural isomers for C 6 H 14 (Answer there are 5). 300

Exercise: Draw and name all the structural isomers for C 6 H 14 (Answer there are 5). The number of structural isomers increases significantly as the number of carbon atoms increases. For example, C 20 H 42 has 366,319 isomers. 301

Number of carbons Number of isomers for alkanes , ,111,846, ,491,178,805,

Stereoisomerism 303

Stereoisomerism Stereoisomerism: Isomers having the same molecular formula and the same atom-to- atom bonding, but the atoms differ in their arrangement in space. 304

Stereoisomerism Stereoisomerism: Isomers having the same molecular formula and the same atom-to- atom bonding, but the atoms differ in their arrangement in space. Geometric isomers: Isomers having the same atom-to-atom bonding, but the atoms differ in their arrangement in space. 305

Examples: The trans and cis isomers of 1,2-dichloroethene. 306

Examples: The trans and cis isomers of 1,2-dichloroethene. trans- 1,2-dichloroethene. 307

Examples: The trans and cis isomers of 1,2-dichloroethene. trans- 1,2-dichloroethene. cis- 1,2-dichloroethene. 308

Examples: The trans and cis isomers of 1,2-dichloroethene. trans- 1,2-dichloroethene. (b.p. 48 o C, m.p. -50 o C) cis- 1,2-dichloroethene. (b.p. 60 o C, m.p. -80 o C) 309

An example from inorganic chemistry. NH 3 Cl NH 3 Cl Pt Pt NH 3 Cl Cl NH 3 cis isomer trans isomer 310

An example from inorganic chemistry. NH 3 Cl NH 3 Cl Pt Pt NH 3 Cl Cl NH 3 cis isomer trans isomer common name: cisplatin 311

An example from inorganic chemistry. NH 3 Cl NH 3 Cl Pt Pt NH 3 Cl Cl NH 3 cis isomer trans isomer common name: cisplatin Only the cis isomer is an effective chemotherapy agent. 312

Optical Isomers - Chirality 313

Optical Isomers - Chirality Polarized Light: Plane polarized light consists of electromagnetic waves with the electric component vibrating in one direction. 314

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Optical Isomer: An isomer that causes rotation of the plane of polarization of light when passed through the substance. 316

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Chiral (sounds like ki ral): An object that cannot be superimposed on its mirror image is called chiral. 318

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mirror plane 321

mirror plane Can superimpose these two molecules; trichloromethane is achiral. 322

mirror plane 323

mirror plane Cannot superimpose these two molecules; bromochlorofluoromethane is chiral. 324

Enantiomers: A chiral molecule and its non- superimposable mirror image are called enantiomers. 325

Enantiomers: A chiral molecule and its non- superimposable mirror image are called enantiomers. The simplest case is a tetrahedral carbon bonded to four different groups. 326

Enantiomers: A chiral molecule and its non- superimposable mirror image are called enantiomers. The simplest case is a tetrahedral carbon bonded to four different groups. Chiral molecules lack molecular symmetry. 327

328

Lactic acid has optical isomers. 329

One optical isomer is sometimes represented by a D (for dextrorotatory: Latin dexter, right) if the rotation of the plane of polarization is to the right; or L (for levorotatory: Latin laevus, left), if the rotation of the plane of polarization is to the left. 330

One optical isomer is sometimes represented by a D (for dextrorotatory: Latin dexter, right) if the rotation of the plane of polarization is to the right; or L (for levorotatory: Latin laevus, left), if the rotation of the plane of polarization is to the left. The symbols + for rotation to the right and - rotation to the left, are also fairly commonly used. 331

One optical isomer is sometimes represented by a D (for dextrorotatory: Latin dexter, right) if the rotation of the plane of polarization is to the right; or L (for levorotatory: Latin laevus, left), if the rotation of the plane of polarization is to the left. The symbols + for rotation to the right and - rotation to the left, are also fairly commonly used. The lactic acid from muscle tissue is D -lactic acid or (+)-lactic acid. 332

A 50:50 mixture of the + and – isomers of the same compound is called a racemic mixture. There is no rotation of the plane of polarization for a racemic mixture. 333

Polymers 334

Polymer: (Greek: poly meros many parts) 335

Polymer: (Greek: poly meros many parts) Very large molecules with molar masses ranging from thousands to millions. 336

Polymer: (Greek: poly meros many parts) Very large molecules with molar masses ranging from thousands to millions. Applications: clothes, food packaging, appliances with plastic components, etc., etc., …. Plastics are polymers. 337

Two basic types of polymer: 338

Two basic types of polymer: 1. Thermoplastics: When heated these soften and flow, when cooled, they harden again. This process can be repeated. 339

Two basic types of polymer: 1. Thermoplastics: When heated these soften and flow, when cooled, they harden again. This process can be repeated. Examples: polyethylene and polystyrene 340

Two basic types of polymer: 1. Thermoplastics: When heated these soften and flow, when cooled, they harden again. This process can be repeated. Examples: polyethylene and polystyrene 2. Thermosetting plastics: When first heated they are plastic, but further heating forms a highly cross-linked structure. Cannot be softened by reheating. 341

Two basic types of polymer: 1. Thermoplastics: When heated these soften and flow, when cooled, they harden again. This process can be repeated. Examples: polyethylene and polystyrene 2. Thermosetting plastics: When first heated they are plastic, but further heating forms a highly cross-linked structure. Cannot be softened by reheating. Example: formica. 342

Monomers: The small (low molar mass) molecules used to synthesize polymers. 343

Synthetic Polymers 344

Synthetic Polymers Two principal reaction types: Addition and condensation. 345

Synthetic Polymers Two principal reaction types: Addition and condensation. Addition Polymers: Made by monomer units directly joining together. 346

Synthetic Polymers Two principal reaction types: Addition and condensation. Addition Polymers: Made by monomer units directly joining together. Condensation Polymers: Made by monomer units combining so that a small molecule, usually water, is split out. 347

Addition Polymers 348

Addition Polymers The monomer for addition polymers normally contains one or more double bonds. 349

Addition Polymers The monomer for addition polymers normally contains one or more double bonds. The polymerization reaction is initiated using an organic peroxide. 350

Addition Polymers The monomer for addition polymers normally contains one or more double bonds. The polymerization reaction is initiated using an organic peroxide. R O O R R O. +. O R 351

Addition Polymers The monomer for addition polymers normally contains one or more double bonds. The polymerization reaction is initiated using an organic peroxide. R O O R R O. +. O R organic peroxide free radicals 352

Initiation step: +. OR. 353

Initiation step: +. OR. 354

Then 355

Etcetera: where n would typically range from 1000 to 50,

Different experimental conditions give different polymers. 357

Different experimental conditions give different polymers. 358

Different experimental conditions give different polymers

Different experimental conditions give different polymers. + branched polymer chain 360

Cross linked polymers are formed in the following manner: 361

Cross linked polymers are formed in the following manner: 362

Cross linked polymers are formed in the following manner: 363

Cross linked polymers are formed in the following manner: 364

Cross linked polymers are formed in the following manner: 365

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cross linked polymer 368

Polyethylene is the most widely used polymer. 369

Polyethylene is the most widely used polymer. The long linear chain version is called high density polyethylene (HDPE) (d = 0.97 g/ml). 370

Polyethylene is the most widely used polymer. The long linear chain version is called high density polyethylene (HDPE) (d = 0.97 g/ml). It is hard, tough, and rigid. Used for milk and detergent containers. 371

The branched chain version is called low density polyethylene (LDPE) (d=0.92 g/ml). The branched chains of polyethylene prevent close packing – hence the density is lower. 372

The branched chain version is called low density polyethylene (LDPE) (d=0.92 g/ml). The branched chains of polyethylene prevent close packing – hence the density is lower. This polymer is soft and flexible. Used for grocery bags, bread bags, etc. 373

The cross linked polymer is called cross-linked polyethylene (CLPE). This is a very tough material. Used for plastic caps on soft drink bottles. 374

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Condensation Polymers 376

Condensation Polymers A condensation reaction occurs when two molecules react by splitting out or eliminating a small molecule such as water. 377

Ester formation reaction: CH 3 CO 2 H + CH 3 CH 2 OH CH 3 CO 2 CH 2 CH 3 + H 2 O acetic acid ethanol ethyl acetate

Polyesters 379 terephthalic acid ethylene glycol H 2 O

Polyesters 380 terephthalic acid ethylene glycol H 2 O Now consider another terephthalic acid molecule reacting with the indicated alcohol functional group.

381 This is an example of the repeat unit for a polyester. In this case it is poly(ethylene terephthalate) called PET.