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Interactions of Hazardous Materials Intro to Organic Chemistry Prepared by: Dolores Gough, P.E. George Gough, P.E., CSP This presentation was prepared to provide some background or refresher notes on selected and limited topics in basic organic chemistry that may be of help for the chemistry portion of the BOS 3640 course. Your textbook is needed for some parts of this presentation. Basic Features of Atoms Atom: smallest particle of an element; composed of smaller particles known as electrons, protons, neutrons Electrons: negative particles responsible for reactivity; charge of -1 Protons: positively charged particles; charge of +1 Neutrons: neutral particles; no charge Electron e -- P+ N Nucleus Protons and neutrons reside within the nucleus. Electrons reside in designated regions surrounding the nucleus called atomic orbitals. Organic Chemistry – chemistry of compounds containing one or more carbon atoms. However, the hydrogen atom is almost always present in these compounds (shown in next slide). Atomic Structure of Carbon - - 6P 6N - Carbon has four (4) electrons in the outer shell that need to bond for stability. Carbon can also share electrons with other carbon atoms to form the following types of carbon bonds: C – C (single bond) C = C (double bond) C Ξ C (triple bond) Hydrocarbons (HC) are compounds whose molecules consist of only carbon and hydrogen atoms. Atomic Structure of Hydrogen - 1P 0N Carbon electron sharing with Hydrogen: Hydrogen has one (1) electron in its outer shell that can share with the C to form covalent bonds. However, C needs to share all 4 electrons in its outer shell. Example: If all four electrons were shared with H, CH4 is formed. H H C H H or CH4 (methane) Carbon – Carbon Single Bond: • • Alkanes: have general formula of CnH2n+2 where n = number of carbon atoms Example: Butane has 4 carbons, all single bonds as shown: H I H I H I H I H - C- C–C-C-H I I I I H H H H • C4H10 (see Table 12.1) Cycloalkanes: same as alkane but the first and last C are linked (closed). In naming them, just add “cyclo” to the alkane name. (Examples – see Sec. 12.2-B) Cyclobutane ( http://commons.wikimedia.org) Cyclohexane http://commons.wikimedia.org Organic Chemsitry Graphics retrieved from http://commons.wikimedia.org Carbon = Carbon Double Bond: • • Alkenes or Olefins: have general formula of CnH2n Example: Butene has 4 carbons and at least 1 double bond H H I I H - C- C=C-C–H I I I I H H H H or C4H8 H H I I H–C=C–C–C-H I I I H H H Carbon Ξ Carbon Triple Bond: • • Alkynes: have general formula of CnH2n-2 Example: Butyne has 4 carbons and at least 1 triple bond H H I I H - C- CΞC-C–H I I H H or H H I I H – C ΞC – C – C - H I I H H C4H6 General Properties/Characteristics: Alkanes (paraffins or saturated HC): relatively stable to chemical reactions. Low molecular weight alkanes are gases or liquids, high MW are solids. Alkenes (olefins ): unsaturated HC because they don’t have the maximum number of atoms each carbon is able to accommodate; physical properties are closely related to those of the corresponding alkanes Alkynes (unsaturated HC): physical properties similar to those of alkanes and alkenes IUPAC System of Nomenclature IUPAC (International Union of Pure and Applied Chemistry – used for naming complex hydrocarbons) When a hydrogen atom is removed from an alkane, the resulting group is called alkyl group or alkyl substituent. See Table 12.2 (page 472) for common alkyl substituents. Rules for naming an alkane (pages 472-473) 1 2 3 4 5 Example: CH3 - CH2 – CH - CH2- CH3 I CH3 3-methyl pentane Methyl (one carbon) IUPAC SYSTEM (cont.) Rules for naming alkenes (1 double bond), dienes (2 double bonds), tienes (3 double bonds) & “cyclos” 1 Examples: 2 3 4 5 CH3CH = CHCH2CH3 1 2 3 2- pentene 4 CH2 = CH – CH = CH2 1, 3 - butadiene Rules for naming alkynes (pages 479-480) 1 Examples: 2 3 4 5 6 CH3CH2C Ξ CCH2CH3 1 2 3- hexyne 3 CH Ξ CCH3 1- propyne Aromatic Hydrocarbons Regarded as compounds whose molecules are composed of one or more special rings of carbon atoms Benzene – simplest aromatic hydrocarbon C 6H 6 http://commons.wikimedia.org Other common aromatic compounds: • Toluene (or methylbenzene) • Xylene 1,4 dimethyl benzene (para-xylene) http://commons.wikimedia.org http://commons.wikimedia.org 1,3 dimethylbenzene (meta-xylene) 1, 2 dimethylbenzene (ortho-xylene) http://commons.wikimedia.org http://commons.wikimedia.org Organic Chemistry Graphics retrieved from http://commons.wikimedia.org Polynuclear Aromatic Hydrocarbons (PAHs) Two or more mutually-fused benzene rings per molecule (when a pair of carbon atoms is shared and the bond between them) Examples: •Naphthalene (C10H8): colorless solid having odor of mothballs; poses chronic respiratory hazard to humans; exposure is llinked with onset of cancerous growths. http://commons.wikimedia.org • Anthracene (C14H10): component of coal-tar. http://commons.wikimedia.org Organic Chemistry Graphics retrieved from http://commons.wikimedia.org Functional Groups In a hydrocarbon, one or more hydrogen atoms may be substituted with another atom or group of atoms. This atom or group of atoms is called the functional group, and this group determines many of an organic compound’s characteristic chemical properties. It identifies an organic compound as alcohol, ether, aldehyde, etc. There are over 100 functional groups; some of the important ones are covered in the book and listed in Table 13.1. Let us take some examples: Functional group: hydroxyl (-OH) Class of organic compound: alcohol General formula: R-CH2-OH Functional group: oxy (-O-) Class of organic compound: ether General formula: R-O-R’ where: R and R’ are arbitrary alkyl or aryl substituent Alcohols •Organic compounds derived by substituting one or more hydrogen atoms in hydrocarbon molecule with hydroxy group (-OH) •General chemical formula of simple alcohol is R-OH Examples: H I Methyl alcohol (methanol) H–C–O–H or CH3OH I H OH 1 3,5 dimethyl 3-hexanol 2 3I CH3 4 5 / 6 CH3 CH2 C CH2 CH I CH3 methyl \ CH3 methyl Ethers • Organic compounds that are highly volatile, flammable liquids • Produce organic peroxides by reacting with atmospheric oxygen catalyzed by light • Highly reactive, potentially explosive • General formula is R-O-R’ Example: Diethyl ether CH3CH2 - O - CH2CH3 (ethyl) (ethyl) Aldehydes and Ketones \ C=O / • Both contain the carbonyl group • Aldehydes - have carbonyl group located at end of chain of carbon atoms • O II R–C–H Ketone - has carbonyl group located at nonterminal position within chain O II R – C – R’ Examples of aldehyde: formaldehyde or methanal (CH2O); acetaldehyde or ethanal (CH3CHO; 2-propenal or acrolein (CH2=CHCHO) Examples of ketone: acetone or 2-propanone (CH3COCH3) methyl ethyl ketone or 2-butanone (CH3COCH2CH3) Organic Acids • Organic compounds containing the carboxyl group (-COOH), so they are also called carboxylic acids. They are weak acids, inherently corrosive, and water-soluble with characteristic odors. • General formula is R – COOH • In the IUPAC nomenclature, the suffix – oic acid is used to designate carboxylic acids; but when the functional group (-COOH) is connected to a cyclic structure, - carboxylic acid becomes the appropriate suffix. • Examples: Methanoic acid (or formic acid): H COOH Ethanoic acid (or acetic acid): CH3 COOH Propanoic acid (or propionic acid): CH3CH2 COOH connected to cyclic structure: 2- hydroxybenzene carboxylic acid (or salicylic): o-HOC6H4 COOH Peroxo-Organic Compounds • Organic hydroperoxides, organic peroxides • Many compounds unstable • Used to induce polymerization, process essential to production of plastics Meyer (2014) Meyer (2014) Chemistry of Hazardous Materials. (6th ed). NJ: Pearson More details and other common hazardous organic chemicals are in the textbook. Reference Meyer, E. (2014). Chemistry of Hazardous Materials. (6th ed.). Upper Saddle River, NJ: Pearson. Organic chemistry graphics retrieved from http://commons.wikimedia.org