Chapter 15: Reactions of Organic Compounds

Complete Combustion Reaction

A hydrocarbon reacts with oxygen to produce carbon dioxide, water vapour, and energy. No matter how complicated the structure, if excess O2 is present all hydrocarbons will burn completely to produce carbon dioxide and water vapour.

Addition Reactions

Undergone by alkanes and alkynes in which atoms are added to a double or triple bond. A small molecules (H2O, H2, HX, X2) is added to a double or triple bond in an alkene or alkyne where X is a halogen. Carbon atoms are bonded to more atoms in the products than in the reactants.

Markovnikov's Rule

In an addition reaction if H2O or HX is added, then there are two possible products that are isomers of each other. The most common is predicted using this rule where the H from the small molecule attaches to the carbon connected to the most # of atoms.

Bromine Water Test

Orange bromine water stays orange with alkanes (C-C single bonds) but becomes clear with alkenes (C=C double bonds). Using bromine water to detect the presence of double or triple bonds in a hydrocarbon. As alkanes are saturated, they cannot participate in addition reactions.

Elimination Reactions

The opposite of addition reactions; atoms are removed form adjacent carbons, and a double bond is formed between the carbons and a small molecule (H2O, HX, X2) is formed; at least one of the two carbons contains a functional group (-OH or -X). Most commonly alkyl halides and alcohols.

- Alcohols: heat and an acid catalyst.

- Alkyl halides: heat and a strong base reactant and an ethanol solvent.

Substitution Reactions

A hydrogen atom or functional group is replaced by a different functional group. Has the following features:

- Two carbons react to form two different compounds.

- Carbon atoms bonded to the same number of atoms in the products as in the reactions.

- Alkyl halides and alcohols are most common to participate in substitution reactions.

- Alkanes are fairly unreactive, so energy is required to substitution H atoms (such as UV radiation).

- Aromatic compounds are also unreactive and require a catalyst.

Esterification Reactions

When al alcohol combines with a carboxylic acid to produce and ester and water. The symbols R and R' in the equation represent different hydrocarbon chains. Typically the Kc is low so a strong acid catalyst is used such as sulfuric acid. This is a type of condensation reaction.

Condensation Reaction

A reaction in which two molecules combine to form a larger molecule, producing a small, stable molecule (usually water) as a second product.

Polymer

A very long molecules that is made by linking together many smaller molecules called monomers. Some polymers contain only one type of monomer or a combination of 2+.

monomers

A small unit that can join together with other small units to form polymers.

Plastics

Synthetic or artificial polymers.

Addition Polymerization

A reaction in which alkene monomers are joined through multiple addition reactions to form a polymer. Addition reaction reaction are characterized by a reduction the number of double bond found on the polymer, as addition reduces a double bond to a single bond.

Condensation Polymerization

Monomers are combined through multiple condensation reactions to form a polymer, A second smaller product, usually water, is also produced, To occur, each monomer must have two functional groups (usually at the end of the molecule).

Polymerization in Petrochemicals

A chemical reaction where small molecules called monomers join to form long chains known as polymers. In the petrochemical industry, this typically involves alkenes like ethene or propene, derived from cracking crude oil fractions. These reactions form addition polymers such as polyethene (plastic bags), polypropene (containers), and PVC (pipes). This process is key in producing synthetic materials from fossil fuels.

PVC

a type of plastic used in almost every industry such as vinyl windows/doors, wall coverings, siding, piep, flooring, and fencing.

1) Ethene is reacted with chlorine in an addition reaction to produce 1,2-dichloroethane.

2) 1,2-dichloroethane product cracked at a high temperature to produce chloroethene (vinyl chloride) and hydrogen chloride via elimination.

3) The byproduct, HCl is cracked further with oxygen an d more ethene to produce 1,2-dichloroethane to be cracked.

4) Vinyl chloride is reacted in addition polymerization to produce polymer PVC.

Vinyl Chloride

A powerful carcinogen found in gas emissions or waste water contaminants from manufacturing plants producing PVC plastics.

Dioxins

A class of chlorinated aromatic hydrocarbons produced as an unwanted by product during the manufacture of PVC. Highly toxic.

Degradable Plastics

Polymers that break down over time when exposed to environmental conditions such as light and bacteria.

Natural Polymers

Found in almost every living system such as cellulose.

Cellulose

A natural polymer that forms wood, paper, cotton and flax. Made of beta linkages (bonds between C and O is drawn up) which is not recognized by enzymes in humans so it will not be broken down.

Starch

Energy storage unit for plants made of repeating glucose monomers. Humans can digest it and it has alpha linkages (bond from C and O is drawn down). It is different from cellulose because it can have branched chains.

Amylose

A straight chained starch.

Amylopectin

A branched chain starch.

Glycogen

A third glucose polymer, an energy storage unit in animals with alpha linkages and more branches than starches creating many free ends allowing enzymes to act on the glucogen polymer at many points simultaneously, increasing the rate at which glucose can be released from storage.

Polysaccharides

Polymers made of sugar monomers called saccharides.

Proteins

A natural polymer made of monomers called amino acids responsible for body processes.

DNA

A biological molecules composed of polymers called nucleotides made of a sugar, phosphate, and cyclic organic molecule containing nitrogen known as the nitrogenous base, Through condensation polymerization, sugar of one nucleotide is linked to the phosphate group of the next.