Ch. 11: Carbon A Multifarious Element

Transcription

1 Ch. 11: Carbon A Multifarious Element

2 Why Carbon? Versatility Single, double, triple bonds Structural diversity

3 Short-hand hand for expressing carbon- based compounds C 4 H 10 : butane Structural formula Condensed structural formula Carbon skeleton formula C 4 H 8 C 4 H 6

4 Isomers Isomers same composition, diff. structures Structural isomers: same # atoms, diff. structures Ethanol (C 2 H 6 O) vs. dimethylether (C 2 H 6 O)

5 Problems Draw all isomers of C 3 H 8 O. There are 3. Draw all isomers of C 4 H 8 Br 2. There are 9.

6 Stereoisomers Same formula, diff. orientation Two types: 1) geometric 2) optical isomers

7 Geometric isomers Require double bond! Cis vs. trans

8 Optical isomers Nonsuperimposable mirror images Called chiral molecules (chirality( chirality) Pairs of chiral molecules = enantiomers

9 Classes of Carbon-Containing Containing Hydrocarbons Only C & H Cmpds Alkane: : C n H 2n+2 (Saturated every C-C C C bond single) Alkene: : C n H 2n (at least one double bond btwn C s) (Unsaturated double, triple bonds)

10 Classes of Carbon-Containing Containing Cmpds Alkyne: : C n H 2n-2 (at least one triple bond btwn C s) Cyclohydrocarbons: : rings of carbon Aromatic: rings w/pi-bonding benzene

11 Naming Alkanes Suffix: -ane Count out longest carbon chain Prefixes: 1C meth- 2C eth- 3C prop- 4C but- 5C pent- 6C hex- 7C hept- 8C oct- 9C non- 10C dec-

12 Naming Alkanes Hydrocarbon substitution = alkyl groups Meth methyl, etc. Use number, followed by -,, to designate placement of substituent 2-methylpentane If 2 or more of same subs. di,, tri, tetra, etc. 2,3-dimethylpentane If more than one different alkyl group, use alphabetic ordering Butyl precede ethyl precedes methyl 4-ethyl-3-methylheptane In naming hydrocarbons always go with longest carbon-chain chain

13 Draw out the following alkanes and rename them, if needed Hexane 2-methylhexane 2,2-diethylpropane 4-ethyl-2-methylnonane Now, I ll I draw some and you name them

14 Naming Alkenes, alkynes Start counting carbon chain from lowest carbon containing double/triple bond 1-propene, not 2-propene2 Use number, followed by -,, to designate placement of double or triple bond 1-butene 2-octyne

15 Draw the following and if there is isomerism draw both structures and name them 1-hexene 2-hexene 3-heptyne 2-methyl-3-heptyneheptyne Now, I ll I draw some and you name them

16 Naming Halohydrocarbons Same rules apply In alphabetical order Bromine bromo chlorine chloro fluorine fluoro iodine iodo Ex: 2-chlorobutane2 Practice (fix if necessary): 3-bromo-2-chloropentane 3,3-diiodobutane Now, I ll I draw some and you name them

17 Naming Aromatic Cmpds Monosubstitution: Methylbenzene toluene Phenol Aniline Disubstitution: o- = ortho m- = meta p- = para

18 Practice Chlorobenzene (does it make a difference where you put the Cl?) Draw all isomers (and name them) of a benzene that has 1 bromine and one fluorine Which combinations are disallowed and why?

19 Other functional groups Functional group = characteristic grouping or arrangement of atoms Alcohols = R-OHR Methanol,, ethanol, propanol,, etc. Structural isomers of alcohols 1,2-ethanediol = ethylene glycol

20 Practice: rename if necessary 1-propanol 2-propanol 3-propanol Now, I ll I draw some and you name them

21 Other functional groups Ether: ROR 1) Select the longest carbon chain and name it as the correct alkane. 2) Change the -yl ending of the other (shorter) hydrocarbon group to -oxy to obtain the alkoxy group name. 3) Combine the two names giving the alkoxy group name first.

22 Practice Dimethylether Butoxyhexane methoxyethane Now, I ll I draw some and you name them

23 Other functional groups Amines RNH 2 Putrescine = 1,4-butanediamine Cadaverine = 1,5-pentanediamine

24 Practice Triethylamine Triisopropylamine Now, I ll I draw some and you name them

25 Other functional groups Aldehydes RCOH Start counting the carbon-chain chain from the C=O Methanal, butanal, hexanalal Ketones RCOR Start counting the carbon-chain chain from the C=O 2-propanone,, 3-heptan3 heptanone

26 Practice Methanal Hexanal 2-pentanone 4-decanone Now, I ll I draw some and you name them

27 Other functional groups Carboxylic acids RCOOH Start counting the carbon-chain chain from the C=O Methanoic acid, ethanoic acid, etc. Esters RCOOR Start counting the carbon-chain chain from the C=O -OR takes on alkyl name RCO takes on oate suffix Thus, HCOOCH 3 methyl methanoate By the way, acetate = ethanoate

28 Practice Hexanoic acid 2-methylpropanoic acid (give its other name) Hexyl ethanoate Butyl butanoate 3-methylbutyl ethanoate (has a more common name) Now, I ll I draw some and you name them

29 Other functional groups Amides RCONR 2 Ex: methanamide, ethanamide

30 Polymers Huge molecules with repeating monomers (subunits) Thermoplastics (polyethylene, styrofoam): respond to heating Soften and flow when heated, harden when cooled; reversible Over 60 million tons of polyethylene produced annually! Thermosetting plastics (Formica-brand): initially soft, but solid when heated; irreversible

31 Styrofoam, Teflon, silicone, Kevlar

32 Condensation Polymers Combining monomers and splitting out small molecules (like water) Demo Demo Making nylon Green snot

33 Green snot

34 Copolymers Polymerization of 2 (or more) diff. monomers Such as: Styrene-butadiene rubber (SBR) Predominately used for car and light-truck truck tires