Chapter 1 Alkanes

the 4 hydrocarbons are

-alkane (saturated, single bond) -alkene (unsat, double bond) -alkynes (unsat, tripple bond) -aromatics (unsat, benzene: single/double bonds) .

physical properties of alkanes

-nonpolar molecules: nonpolar c-c bonds -have lower melting points and boiling points than other organic componds. (this is because their nopolar molecules exert very weak attraction for each other) -are oderless compounds

cycloalkane structural formula/condensed formula cyclopropane cyclobutane cyclopentane cyclohexane

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step 1

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step 2

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step 3

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at normal temperture and pressure alkanes (what state of matter compared to how many carbon atoms in the molecule)

1 to 4 carbon atoms are gasses 5 to 20 carbon atoms are liguids 20+ carbon atoms are solids

Useful steps when IUPAC names

1. name the longest chain: the longest continous chain is chose as the basis for the name 2. number the longest chain: the carbon atoms in the longest chain numbered consecutively from the end that will give the lowest possible number to any carbon to which a group is attched ex: .(34)

tetrahedral shape

109.5' this is the most stable bond forms. because results in the least crowding of an atom CH4 is an example

Ethane

C2H6 CH3-CH3 tetrahedral shape 109.5' minor component to natural gas

propane

C3H8 CH3-CH2-CH3 used as industrial fuel (heating, cooking) can produce this molcule by removing hydrocarbon atom from the precedings compound (ethane) and substituting -CH3)

butane

C4H10 there is more than one position avaliable: you can add on the extra CH3 at the end (CH3-CH2-CH2-CH3) or you can add it in the middle (CH3-CH-CH3) CH3 can put an extra

methane

CH4 tetrahedral shape 109.5' primary compound found in natural gas (effiecent, clean burning fuel)

Pentane has ___ isomers hexane has ___ isomers

Pentane has _3__ isomers hexane has __5_ isomers more complicated the compound, the greater the number of isomers

The 2 possible butanes have a strucural formula of C2H10 they are structural isomers of eachother

The 2 possible butanes have a strucural formula of C2H10 they are structural isomers of eachother but they have different atom to atom bonging sequence

it is important to remember that each carbon atom is still posses four bonds.

The carbons will have two hydrogen bonds unless they are bonded to something else.

functional group

a group of atoms responsible for the characteristic reactions of a particular compound

expanded structural formula

a structural molecular formuala showing all covalent bonds

condensed structural formula

a structural molecular formula showing the general arrangment of atoms but without showing all covalent bonds

alkane reactions

alkanes are the least reactive out of all organic compounds. they do not react with strong acids, strong bases, most oxidizing agents, or most reducing agents.

cycloalkane

alkanes containing rings of carbon atoms not found in the human cell chemist often abbreviate the structural formulas of cycloalkanes and draw them as geometric figures (triangle, square, penta) each corner represenets a carbon

what makes an organic compound

all contain carbon carbon: earth would become the moon with out carbon

if two or more alkyl groups are present their names are

alphabetized and added to the name of the basic alkane, again as one workd.

branched alkane

an alkane in which at least one carbon atom is not part of a continous chain * the number of possible structural isomers increase dramatically with the umber of carbon atoms in an alkane

normal alkane

any alkane in which all the carbon atoms are aligned in a continous chain

hydrocarbons

are the simpliest of all organic compounds. they contain only two elements= carbon and hydrogen

boiling points of normal alkanes increase

boiling points of normal alkanes increase smoothly as the length of carbon chain increases. this patterm results from the increasing dispersion forces as molecular weight increases

naming n-butane

but (4 carbon) ane (alkane family) n=all carbons form an unbranched chaine CH3CH2CH2CH3

removing the hydrogen from the center carbon results in an isopropyl group

can be represented by (CH3)CH- .(page 33)

alkyl

can be thought of as a collection of atoms of an alane minus one hydrogen atom

alkane

carbon- carbon bonding a hydrocarbon that contains one single bond general formula: CnH 2n+2 (n=carbon#)

why is cis and trans important

cis and trans have chemical properties that are quit different

homologous series

compounds of the same functional class that differ by a CH2 group the normal or straight chain alkanes make up this. this term describes any series of compound in which member diff from pervious member only by having an additional CH2 unit.

steroisomerism

compounds with the same strucutral formula but different spatial arrangements of atoms. ex: Cis 1,2 dimethylcyclopentane (cis= methyl on same side applies to geometric isomers) trans 1,2 dimethylcyclopentane (trans=methyl on opposite sides applies to geometric isomers) .

angles of cyclopropane angels in cyclobutane

cyclopropane (triangle shape) angle about 60' cyclobutane (square) angle about 90' (they bend to prevent overcrowding of the atoms) these rings are much less stable then compounds with bond angles of 109.5'

perhaps the most significant reaction of alkanes

is rapid oxidation called combustion. in the presence of ample oxygen, alkanes burn to form carbon dioxide and water

naming isobutane

iso=all carbons except 1 are in a continous chain and in wich that one carbon is branched from a next to the end carbon ex:

desity of alkanes

less dense than water so can float on water

simplest alkane

methane

alkyl group

methyl (CH3-) ethyl (CH3CH2-) propyl isopropyl butyl sec buyl isobutyl t-butyl (tertiary-butyl) .

Number of carbon atoms 1 2 3 4 5 6 7 8 9 10

molecular formula/structure of normal isomers 1 methane CH4 2 ethane C2H6 3 propane 4 butane 5 pentane 6 hexane 7 heptane 8octane 9 nonane 10 decane

geometric isomers

molecules with restricted roations around the c-c bond that differ in the 3 dimenstional arrangments of their atoms in space and not in order of linkage of atoms to exist as geometric isomers, a disibsitited cycloalkane must bond to groups at two different carbons of the ring.

are alkanes soluable in water

no because they are nonpolar (because water is highly polar solvant)

inorganic compounds

no carbon in the atoms CO, CO2, carboate and cynaide (are exceptions)

hybrid orbitals

orbitals produced by combination of 2 or more non equivalent orbitals. ex: CH4 electron configuration: Hybridized: .

Diff between organic and inorganic compounds

organic: -contains carbon (1 element) -9 million compounds -covalent bonds -normal physical state gases, liquids, low melting point -often flamable -slow chemical reactions -low soluability in water inorganic -contains 100 + elements -500,000 compounds -ionic bonds -normally high melting point solids -nonflammable -high solubility in water -fast chemical reaction

how to name a cycloalkane

prefix: cyclo in front of the corresponding alkane.

IUPAC naming system prefix root ending

prefix= denotes number and identity of attached groups (are used to identiry, nmber, and location of atoms or groups of atoms that are attached to the longest carbon chain) root= denotes longest chain carbon (based on the meth, eth, prop, but, etc) ending= denotates functional class (-ane= alkane)

how do structural formulas help idenity isomers

strucutral formular: a formula that shows the arrangement of atoms in the molecule of a compound. isomers: each of two or more compounds with the same formula but a different arrangement of atoms in the molecule and different properties. (same molecular formula, diff atom arrangments) if you can see the strucutre of the atom you can see if they are isomers

conformations

the different arrangements of atoms in space acheived by rotation about single bonds a molecule can exist in many different oreintations in a sample of butane containing billions of identical molecules, there are countless conformations present at any instant, and each conformation is rapidly changing into another. these different conformations do not represent different structural isomers.

rotations of cycloalkanes

the free rotations of cycloalkanes is not possible. the ring structure allows for beding or puckering but prevents free rotation. the lack of rotation around the c-c bond leads to an extremely important kind of isomerism called steroisomerism

hydrophobic

water fearing is often used to refer to molecules or parts of molecules that are insoluable in water

attached groups on the cycloalkane

when subsituted cycloalkanes (those attached groups) are named, the position of a single attached group does not need to be specified in the name, bc all position in the rings are equivalent. however, when there are two or more groups attached their posion is indicated. the ring numbering begins with the carbon attached to the first group alphabetically and proceeds around the ring in the direction that will give the lowest numbers for the location of the other attached group