organic chemistry – the study of carbon compounds biochemistry – the study of the chemistry of living species 25.2: Introduction to Hydrocarbons made of only hydrogen and carbon 4 types: alkanes, alkenes, alkynes, and aromatic hydrocarbons alkanes – only single bonds also called saturated hydrocarbons have the largest amount of hydrogen atoms bonded to a single carbon atom alkenes (olefins) – have double carbon bonds alkynes – triple carbon bonds aromatic hydrocarbons – carbon atoms connected in a planar ring structure, joined by s and p bonds between carbon atoms alkenes, alkynes and aromatic hydrocarbons – unsaturated hydrocarbons less volatile with increasing molar mass very low molecular weight = gas at room temperature moderate molecular weight = liquid high molecular weight = solid 25.3: Alkanes methane major part of natural gas used in home heating, gas stoves, hot-water heaters propane major part of bottled gas used for home heating, cooking butane – used in disposable lighters, fuel canisters alkanes with 5-12 carbon atoms are found in gasoline formla for alkanes is called condensed structural formulas Molecular Formula Condensed Structural Formula Name Boiling point (°C) CH4 CH4 Methane -161.0 C2H6 CH3 CH3 Ethane -89.0 C3H8 CH3 CH2 CH3 Propane -44.0 C4H10 CH3 CH2 CH2 CH3 Butane -0.5 C5H12 CH3 CH2 CH2 CH2 CH3 Pentane 36.0 C6H14 CH3 CH2 CH2 CH2 CH2 CH3 Hexane 68.0 C7H16 CH3 CH2 CH2 CH2 CH2 CH2 CH3 Heptane 98.0 C8H18 CH3 CH2 CH2 CH2 CH2 CH2 CH2 CH3 Octane 125.0 C9H20 CH3 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH3 Nonane 151.0 C10H22 CH3 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH3 Decane 174.0 Lewis Structure Structures of Alkanes tetrahedral geometry carbon-carbon single bond rotates easily at room temperature long chains tend to change shape Structural Isomers straight-chained hydrocarbons – carbons atoms that are joined in a continuous chain branched-chain hydrocarbons – hydrocarbons with branched chains, 4 or more carbon atoms structural isomers – compounds with the same molecular formula but different bonding arrangements Nomenclature of Alkanes 1) Find the longest continuous chain of carbon atoms, and use the name of this chain as the base name of the compound. 2) Number the carbon atoms in the longest chain, beginning with the end of the chain that is nearest to a substituent 3) Name and give the location of each substituent group 4) When two or more substituents are present list them in alphabetical order Cycloalkanes alkanes that form rings or cycles carbon rings with fewer than five carbon atoms are strained more reactive Reactions of Alkanes at room temperature alkanes do not react with acids, bases, or strong oxidizing agents important for it’s combustion in air; bases for fuels 25.4: Unsaturated Hydrocarbons Alkenes double carbon bonds ethene or ethylene simplest alkene\ nomenclature of alkenes come from the name of the corresponding alkane the –ane ending is changed to –ene geometrical isomers – compounds that have the same molecular formula and the same groups bonded to one another but differ in the spatial arrangement of these groups geometrical isomers have distinct physical properties and differ in chemical behavior the double carbon bond is resistant to twisting rotation about a double bond is a key process in the chemistry of vision Alkynes one or more triple bonds simplest alkyne is acetylene highly reactive named by changing the alkane ending (-ane) to –yne Addition Reactions of Alkenes and Alkynes addition reactions – a reactant is added to the two atoms that form the multiple bond hyrogenation – reaction between al alkene and H 2 Aromatic Hydrocarbons simplest is benzene stability comes from the stabilization of the p electrons through delocalization in the p orbitals represented by a hexagon with an inscribed circle substitution reactions – one atom of a molecule is removed and replaced by another atom or group of atoms 25.5: Functional Groups functional group – site of reactivity in an organic molecule; controls how the molecule behaves or functions chemistry of an organic molecule is determined by the functional groups it contains Alcohols (R-OH) alcohols – hydrocarbon derivatives in which one ore more hydrogens of a parent hydrocarbon have been replaced by a hydroxyle or alcohol functional group Ethers (R-O-R’) ethers – two hyrocarbon groups are bonded to one oxygen formed from two molecules of alcohol by splitting out a molecule of water condensation reaction – reaction where water is split out from two substances used in solvents 25.6: Compounds with a Carbonyl Group carbon oxygen double bonds Aldehydes and Ketones carbonyl group in aldehydes has at least one attached hydrogen atom formaldehyde carbonyl group in ketones occurs at the interior of a carbon chain Acetone prepared by oxidizing alcohols Carboxylic Acids carboxylic acids contain carboxyl functional group (COOH) important for manufacturing of polymers produced by oxidation in which the OH group is attached to the CH 2 Esters carboxylic acids that undergo condensation with alcohols have pleasant odors saponification – hydrolysis of an ester in a base Amines and Amides amines – organic bases; general formula R 3 N amides – anines containing a hydrogen bonded to nitrogen that undergoes condensation 25.8: Introduction to Biochemistry biosphere – part of the earth where living organisms are formed and living includes influences on life of the atmosphere, natural waters, solid earth living organisms require a large amount of energy biopolymers – three categories: proteins, polysaccharides (carbohydrates), and nucleic acids 25.9: Proteins macromolecular substances 50% body’s dry weight is proteins composed of amino acids Amino Acids differ in the R group building block of all proteins - a -amino acid general form: chiral - any molecule containing a carbon with four different attached groups enantiomers – mirror-image of chiral enantiomers and chiral have the same physical properties differ in chemical reactivity toward other chiral molecules Polypeptides and Proteins peptide bond – condesation reaction between the carboxyl group of one amino acid and the amino group of another amino acid polypeptides – large number of amino acids that are linked together by peptide bonds proteins are polypeptide molecules weighs from 6000 to over 50 million amu Protein Structure primary structure – arrangement of amino acids along a protein chain makes the protein unique secondary structure – the way segments of the protein chain are oriented in a regular pattern a -helix – most important and common secondary structure arrangement first propoesed by Linus Pauling and R. B. Corey tertiary structure – overal shape of a protein globular protein – a protein that folds into a compact spherical shape soluble in water, mobile within cells enzymes – large protein molecules that serve as catalysts 25.10: Carbohydrates written as C x (H 2 O) y glucose the most abundant carbohydrate C 6 H 12 O 6 not really hydrates of carbon but polyhydroxly aldehydes and ketones Disaccharides monosaccharides – simple sugars that can’t be broken into smaller molecules by hydrolysis with aqueous acids disaccharide – two linked monosaccharides two common disaccharides: sucrose, lactose Polysaccharides made of several monosaccharide units starch – group of polysaccharides food storage in plant seeds and tuers glycogen – starchlike substance synthesized in the body 5000 to more than 5 million amu energy bank in the body; muscles and liver cellulose – major strructural unit of plants straight chains of glucose units more than 500,000 amu 25.11: Nucleic Acids nucleic acids – biopolymers that are chemical carriers of an organisn’t genetic information deoxyribonucleic acids (DNA) – huge molecules with molar weights of 6-16million amu ribonucleic acids (RNA) – smaller molecules with molecular weights of 20,000 to 40,000 amu DNA found inside the nucleus of a cell, RNA found outside nucleus in the cytoplasm DNA stores the genetic information of the cell and controls the production of proteins RNA carries information from the DNA out of the nucleus Monomers of nucleic acids (nucleotides) have three parts: A phosphoric acid molecule, H 3 PO 4 A five-carbon sugar ribose A nitrogen-containing organic base deoxyribose deoxyribose has one less oxygen atom at carbon 2 than ribose nucleic acids are polynucleotides DNA molecules made of two DNA chains that form a double helix