Chpter 7 LS

In fact, the dipole moment of trans-CH3CH═CHCltrans-CH3CH═CHCl is larger than that of H2C═CHClH2C═CHCl, indicating that a methyl group acts as an electron-donating substituent on the double bond.

(pg 252) -A methyl group releases electrons to an attached double bond in much the same way that it releases electrons to an sp2-hybridizedsp2-hybridized carbon of a carbocation—by an inductive effect and by hyperconjugation.

Reaction conditions, such as the acid used and the temperature, are chosen to maximize the formation of alkene by elimination.

*Sulfuric acid (H2SO4)(H2SO4) and phosphoric acid (H3PO4)(H3PO4) are the acids most frequently used in alcohol dehydrations.* Potassium hydrogen sulfate (KHSO4)(KHSO4) is also often used

compounds that contain both a double bond and a hydroxyl group combine the suffixes __ + __ to signify that _____ functional group(s) is/are present

-en, -ol, both

Describe elimination reactions

-groups are lost from starting materials -a pi bond is formed in the product

Stereoisomers

2 alkenes in which the only structural differenc is the relative positions of the grouos attached to the double-bonded carbons -they are labeled as cis- and trans- in simple alkenes

What statement would most consistently match the reaction pathway with the mechanism symbol SN1?

2-Bromo-2-methylbutane undergoes hydrolysis by this mechanism -Because the substrate is crowded around the leaving group, substitution must occur through an SN1 mechanism

Which of the following about stereoisomers are true? (select all that apply) 1. all alkenes exhibit cis/trans isomerism 2. all sterioisimers are isomers, but not all isomers are stereoisomers 3. any two alkene structures with the same molecular formula MUST be stereoisomers of each other 4. any cis-alkene must have a trans stereoisomer

2. all sterioisimers are isomers, but not all isomers are stereoisomers 4. any cis-alkene must have a trans stereoisomer

What statement would most consistently match the reaction pathway with the mechanism symbol E1?

A mechanism that can give a product with a different carbon skeleton from the substrate

locant naming

According to various versions of the IUPAC rules, the locant may precede the parent chain or the -ene suffix

_____ is the term used to describe the loss of hydrogen and a halogen from an alkyl halide. The product of the reaction is a(n) _____.

Dehydrohalogenation, alkene

True or False? Cyclobutane can be either cis- or trans-

False: **add explanation from pics

Parent alkene

The alkene corresponding to the longest continuous chain that includes the double bond is considered the *parent* -chain is numbered in the direction that gives the doubly bonded carbons their lower numbers.

What statement would most consistently match the reaction pathway with the mechanism symbol E2?

The major product in the reaction of cyclohexyl bromide with sodium ethoxide in ethanol is formed by this reaction -alkyl halides primarily undergo E2 eliminations in the presence of Lewis bases

What statement would most consistently match the reaction pathway with the mechanism symbol SN2?

Unhindered primary halides react with amines by this mechanism -lack of hindrance and relatively weak base promote SN2 substitutions

2-isopropyl-4-methyl-1-pentane -the longest continuous chain that includes both c atoms and is a double bond of carbon

What is the IUPAC name of the alkene shown?

2-isopropyl-4-methyl-1-pentene

What is the IUPAC name of the alkene shown?

3-ethyl-2-pentene

What is the IUPAC name of the alkene shown?

1-ethyl-5-isopropylcyclohexane

What is the IUPAC name of the compound shown?

**** dont know the answer*** eek

What is the major treatment of tosylate shown with potassium tert-butoxide and a mixture of (CH3)3

Structure C and structure B

Which of the follosing compounds would be the products for the following reactions? (select all that apply)

cycloheptene

_____ is the IUPAC name of the compound shown.

What takes precedence over alkyl groups and halogens in determing the main carbon chain and the directino in which itis numbered?

carbon-carbon double bonds

_____ is a β elimination rxn where H20 is eliminated from an alcohol to give a(n) _____.

dehydration, alkene

Dehydrohalogenation

describes the loss of hydrogen and a halogen from an alkyl halide. The product of the reaction is an alkene

Alkene IUPAC names

givenby replacing the -ane ending of the corresponding alkane with -ene

HOMO

highest occupied molecular orbital (π1), doubly occupied -occurs at the same time as LUMO

alkenes

hydrocarbons that contain a carbon-carbon double bond

trans-

in simple alkenes, these are labeled as having 2 identical groups on opposite sides

cis-

in simple alkenes, these are labeled as having 2 identical groups on the same side

LUMO

lowest unoccupied molecular orbital (π2), vacant -occurs at the same time as HOMO

Naming Cycloalkenes (and their derivatives)

named by adapting cycloalkane terminology to the principles of alkene nomenclature.

Molecular orbital theory (MO)

offers an alternative to the valence bond theory for understanding the structure of alkenes. Recall from Section 2.4 that the number of molecular orbitals is equal to the number of atomic orbitals (AOs) that combine to form them. When we combine the two 2p AOs, one from each of the sp2-hybridizedsp2-hybridized carbons of ethene, the two π MOs are formed

ethyelene

planar, each carbon is sp2-hybridizedsp2-hybridized, and the double bond has a σ component and a π component. The σ component arises from overlap of sp2 hybrid orbitals along a line connecting the two carbons, the π component via a "side-by-side" overlap of two p orbitals.

The shape of an organic molecule is influenced by its _____, and the double bond is the site of most of the chemical reactions that _______ undergo.

presence, alkenes

True or False? Both inductive effects and hyperconjugation cause methyl groups to release electron destiy to attached C=C double bonds

true