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ORGANIC CHEMISTRY Chapter 25 Vacation packet #2 Mrs. Brunet Our extent of Organic Chemistry for the AP test is pretty limited…yeah! As part of the Descriptive Chemistry, you need to know: “3. Introduction to organic chemistry: hydrocarbons and functional groups (structure, nomenclature, chemical properties)” Organic Chemistry is the study of carbon containing compounds. Before 1828 the vital force theory, which stated that organic compounds could be extracted only from living, or once living organisms, was widely accepted. Only to be dashed by Friedrich Wohler’s synthesis of urea (not urine but a component of it), an organic compound from the heating of an organic compound from the heating of an inorganic compound. Check out the organic chemist’s version of our favorite periodic table Carbon exists as an element in three different forms, called allotropes: graphite, pencil “leads”; diamond, a girl’s best friend; and buckministerfullerene, or the bucky ball (looks like a hollow soccer ball). [25.1] The basics of our expected o-chem knowledge for the AP exam (chemmy bear link = study cards): http://www.chemmybear.com/apch23sc.pdf Nomenclature Functional groups Properties of compounds How to draw various types of isomers Nomenclature of organic compounds is based upon the structure of the molecule Straight chain of carbons (normal or n-) Branched chains Cyclic molecules, rings like benzene ORGANIC CHEMISTRY Chapter 25 Vacation packet #2 Mrs. Brunet Let’s start with the basics and we will build on those. I know this stuff looks big and bad but it’s really quite simple…honest engine. Don’t be fooled by the IUPAC logo, it just stands for International Union of Pure and Applied Chemistry. I suggest you make your own clever acronym for this stuff. Check out section 25.2-25.3, your book has a good plan for naming hydrocarbons. First of all the basis of the names is on the number of carbon atoms that make up the structure. The last name consists of one of the following roots: # of carbons in the longest chain 1 2 3 4 5 6 7 8 9 10 Root MethEthPropButPentHexHeptOctNonDec- Second is the suffix of the last name and that depends upon the type of bonds between the carbons. One of more of these types All single bonds At least one double bond At least one triple bond Suffix of name -ane -ene -yne ORGANIC CHEMISTRY Chapter 25 Vacation packet #2 Mrs. Brunet Let’s start with alkanes which are single (sigma, this is a little ahead for us but every single covalent bond is called a sigma bond) bonded molecules. These have the general formula CnH2n+2. Alkanes containing fewer than 5 carbons are gases (propane, the outdoor barbeque fuel) 5-15 are liquids (like kerosene and gasoline), and >16 are solids (paraffin or wax). Alkanes are said to be saturated because they have all single bonds. This molecule can be drawn structurally (above) or made with 3D models or written condensed: CH3CH3 This is ethane because there are two carbons in the longest chain and only single bonding. Many times hydrogens are omitted to make the structural formula simpler, or condensed. This can be useful when the longer chains are being used: C—C—C—C also written as CH3CH2CH2CH3 or where each end represents a carbon Four carbons in a straight chain, this is n-butane. The n stands for normal or straight chain. The name here changes even though there are still four carbons. Branched hydrocarbons (hydrogen and carbon compounds) are named based upon the longest chain. Anyway, you look at this molecule it has three continuous carbons thus propane. But we must name the branched part. Since the branched part is one carbon atom, the name still comes from the prefixes, meth-, but we substitute the suffix –yl and add it to the beginning of the name for the longest chain METHYL PROPANE or more commonly, isobutane. ORGANIC CHEMISTRY Chapter 25 Vacation packet #2 Mrs. Brunet For the longer chains the placement of the side group is denoted by numbering. The longest carbon chain is numbered with the lowest numbering associated with the side groups. The name for this molecule is 2-methylpentane. The other option 4-methylpentane would be incorrect because 2 is a lower value. The longest chain is five and all single bonds with a side group off of the second carbon. The rules for naming alkanes are condensed in a table on pg. 1068 and good examples on pg. 1069. Look at exercises 25.1 on pg. 1071, and 25.2 on pg. 1072. Check out a few more examples at http://www.sciencegeek.net/APchemistry/APtaters/alkanes.htm You should now be ready to do homework #1 CYCLOALKANES Arranged in a cyclic pattern, these occur with the general formula of CnH2n The names use the same parent name, adding the prefix “cyclo” to describe the shapes. For naming rules and practice see science geek.com: http://www.sciencegeek.net/APchemistry/APtat ers/cycloalkanes.htm UNSATURATED HYDROCARBONS http://www.organicchemistry.com/tag/unsaturated-carbon/ ALKENES [25.4] ORGANIC CHEMISTRY Chapter 25 Vacation packet #2 Mrs. Brunet -unsaturated hydrocarbons occurring in CnH2n but are not cyclic. These are said to be unsaturated because the double bond can open up and become saturated with more hydrogen or other substituents. -naming: Use longest chain containing a double o Over 10 million tons/year bond, can by cyclic also produced o Used in refining of petroleum 2-Butene Also for production of plastics, antifreeze, synthetic fibers, and solvents Ethylene IUPAC name Use the lowest number for the first IUPAC name[hide] double-bonded carbon Suffix of hydrocarbon changes to – Ethene ene to represent the double bond Ethene (ethylene) ORGANIC CHEMISTRY Chapter 25 Vacation packet #2 Mrs. Brunet Propene (propylene) PPE o Plastics and synthetic fibers IUPAC name[hide] Propene Propene ALKYNES more from science geek: ardbanks/organic/nomenclature/aromaticno http://www.sciencegeek.net/APchemistry/or menclature1.htm ganic/alkene_alkyne.shtml General formula of CnH2n-2 , very reactive, unsaturated Contains at least one triple bond Suffix changes to –yne *Note: If there are two or more triple bonds, they are called alkadiynes (two triple bonds), alkatriynes (three triple bonds), and so on, NOT alkynes. This also applies to the alkenes. HW 2 p. 1110 #6,8,12,22,24 AROMATIC HYDROCARBONS http://chemistry.boisestate.edu/people/rich Benzene ORGANIC CHEMISTRY Chapter 25 Vacation packet #2 Mrs. Brunet IUPAC name[hide] Benzene Cyclic and unsaturated C6H6 is the most simple, benzene Aromatic compounds are generally derived from benzene Most have distinctive odors, but not all Used in plastics, fibers, explosives, paint, and petroleum FUNCTIONAL GROUPS p1083 HALOGEN DERIVATIVES Compound has a halogen atom(s) substituted for a hydrogen atom(s) Halogen names are treated like prefixes to the parent name F=fluoro-; Cl=cloro-; Br=bromo-; I=iodo- Chloroform IUPAC name[hide] Chloroform Systematic name[hide] Trichloromethane Other names[hide] Formyl trichloride, Methane trichloride, Methyl trichloride, Methenyl trichloride, TCM, Freon 20, R-20, UN 1888 ORGANIC CHEMISTRY Chapter 25 Vacation packet #2 Mrs. Brunet HALOHYDROCARBONS (sounds like a video game, huh?) Replacement of hydrogen in a hydrocarbon with one or more halogens Nomenclature follows rules of previous sections ALCOHOLS 1,2-ethanediol or antifreeze An hydroxyl (-OH) is attached to the end of the hydrocarbon or R For naming, drop –e parent hydrocarbon with –d Number placement of hydroxyl group with smallest possible Alcohols can be primary, secondary, or tertiary The lower molecular mass alcohols are soluble in water through hydrogen bonding with the water. Alcohols with four or more carbon atoms however, have such a large nonpolar part of the molecule that they are not soluble in water, a polar solvent. ETHERS Organic oxides with –O- within the body of the molecule Nomenclature follows basic hydrocarbon rules for both sides of R-O-R, followed by the second name, ether. ORGANIC CHEMISTRY Chapter 25 Vacation packet #2 Mrs. Brunet dimethyl ether ALDEHYDES Contain a carbonyl group bonded to at least one hydrogen atom Nomenclature drops final –e and adds –al and a number indicating the position of the carbonyl group, where necessary. (aldehyde carbon is always #1) Aldehydes have strong odors; two of the best are vanillin (left) and cinnamadlehyde KETONES Carbonyl group BUT bonded to two carbon atoms, in the middle Nomenclature drops the final –e then adds –one Number the placement of the carbonyl group Ketones are used as solvents, you use this one on the white boards all the time! ORGANIC CHEMISTRY Chapter 25 Vacation packet #2 Mrs. Brunet CARBOXYLIC ACIDS Carboxyl is from “carbonyl” and “hydroxyl” Naming: drop –e then add –ioc acid Weak acids, such as acetic acid, the active ingredient in vinegar Formic acid (or methanoic acid) is the agent that causes pain from an ant bite ESTERS Often have sweet, fruity odors Esters are formed from an alcohol and an organic acid Naming: the names of the alcohol is first, dropping the –ol and adding –yl, next the name of the acid drops –oic and adds –ate Some esters are used as substitutes for natural products and enhancers in food. Remember the first lab? You were to identify the ester; some of you smelled octyl acetate, orange aroma; or ethyl butyrate, pineapple aroma. Other fun ones: methyl butyrate, apple; isopentyl acetate, banana; pentyl propionate, apricot; isobutyl formate, raspberry, benzyl acetate, jasmine Are you a fan of grapples? You can make your own with regular apples and grape ester found in grape koolaid. http://www.ehow.com/how_5907945_make-grapple-apple.html ORGANIC CHEMISTRY Chapter 25 Vacation packet #2 Mrs. Brunet Wintergreen lifesavers have wintergreen oil and can produce a visible spark when cracked. Live a little…try it! http://www.ehow.com/how_2097426_make-light-sparklifesaver.html AMINES Amines are related to ammonia, NH3…you remember ammonia? A friend of the gravimetric plant food lab Starting with NH3 replacing one H with a carbon chain (primary); two H’s (secondary); or three H’s (tertiary). This makes an amine. Amines are organic versions of bases Amines are responsible for unpleasant odors like decaying tissue, old fish Aromatic amines (carcinogens) are used to make dyes. Be careful! Complex molecules use amino- for the -NH2 functional group HW 3 p. 111-2 #40,46,52 TYPES OF ORGANIC REACTIONS: 1] Substitution: replacing of one functional group by another ORGANIC CHEMISTRY Chapter 25 Vacation packet #2 Mrs. Brunet 2] Addition: it is common for alkenes to break one bond and gain two substituents. 3] Elimination: one product is removed, leaving an unsaturated hydrocarbon, also is called dehydration 4] Esterification: an alcohol reacts with an organic acid to make an ester 5] Saponification: esters are split into alcohols and salts of carboxylic acids; triglycerides can be treated with aqueous sodium hydroxide to form glycerol and soaps. HW 4 p. 1111 #32 ORGANIC CHEMISTRY Chapter 25 Vacation packet #2 Mrs. Brunet ISOMERS Two organic compounds may have formulas with exactly the same atoms but different properties. These compounds are called isomers, there are three types: structural isomers, cis- and trans- isomers, stereoisomers. Structural Isomers: Butane and allother alkanes exhibit structural isomerism. For example, butane can exist as a straight chain or n-butane (normal butane). The branched isomer of butane is called isobutene: Isomers can be difficult to figure and draw, just remember to count the longest continuous chain. This can often show that some may appear as isomers but really are the same arrangement. With alkenes and alkynes, try moving the multiple bond around to different locations because multiple bonds are rigid. Isomers are discussed all throughout the organic chemistry tutorial by science geek.com http://www.sciencegeek.net/APchemistry/organic/ochem.shtml Cis- and Trans- Isomers: These isomers refer to molecules that contain atoms or groups of atoms in different positions around a rigid ring (rigid = contains multiple bonds) or bond. Cis- means “on the same side”; Trans- means “on opposite sides” and refers to groups attached to double-bonded carbon atoms. The double bond is the key to the distinctly different molecules which have different chemical and physical properties as a result of their structures. Stereoisomers or Optical Isomerism: These isomers are the hardest to recognize and take considerable brain power and spatial thinking to work with; they have the same formulas, and every atom is bonded to the same atom. These are not structural isomers, but they are not exactly ORGANIC CHEMISTRY Chapter 25 Vacation packet #2 Mrs. Brunet the same. I have to actually make models to get this and fortunately we are born with two perfect stereoisomers. Left hand meet right hand. (or feet) They are the same in every way, yet they are not identical. They are mirror images of each other and that, girls and boys, is a stereoisomer! Stereoisomers, unlike cis- and trans- isomers, have identical physical properties such as melting and boiling points. The chemical reactivity of two stereoisomers is, for the most part, identical also. However, stereoisomers often have different chemical reactivites in biological systems (like us) where the overall shape of the molecule is important. Most amino acids have two stereoisomers. In all known living matter the stereoisomers are those that rotate light to the left. Yet synthetic production of pharmaceuticals produces 50:50 right and left isomers, even when only one is effective as a drug. Production of only one of the isomers is possible but very expensive….sound familiar when considering prescription medication? HW 5: AP Problems 2002 B Consider the hydrocarbon pentane, C5H12 (molar mass 72.15 g). (a) Write the balanced equation for the combustion of pentane to yield carbon dioxide and water. (b) What volume of dry carbon dioxide, measured at 25˚C and 785 mm Hg, will result from the complete combustion of 2.50 g of pentane? (c) The complete combustion of 5.00 g of pentane releases 243 kJ of heat. On the basis of this information, calculate the value of ∆H for the complete combustion of one mole of pentane. (d) Under identical conditions, a sample of an unknown gas effuses into a vacuum at twice the rate that a sample of pentane gas effuses. Calculate the molar mass of the unknown gas. (e) The structural formula of one isomer of pentane is shown below. Draw the structural formulas for the other two isomers of pentane. Be sure to include all atoms of hydrogen and carbon in your structures. ORGANIC CHEMISTRY Chapter 25 Vacation packet #2 Mrs. Brunet 2003 D Compound Name Compound Formula ∆H˚vap (kJ mol-1) Propane CH3CH2CH3 19.0 Propanone CH3COCH3 32.0 1-propanol CH3CH2CH2OH 47.3 Using the information in the table above, answer the following questions about organic compounds. (a) For propanone, draw the complete structural formula (showing all atoms and bonds); (b) For each pair of compounds below, explain why they do not have the same value for their standard heat of vaporization, ∆H˚vap. (You must include specific information about both compounds in each pair.) (i) Propane and propanone (ii) Propanone and 1-propanol (c) Draw the complete structural formula for an isomer of the molecule you drew in, part (a) (i). Testing Review Naming alkanes: http://www.sciencegeek.net/APchemistry/APtaters/chap22alkanes.htm Naming Chemical Compounds PowerPoint is good review up until slide 27 where the organic chemistry starts! I found this on the internet and lost the citing information…oops.