Chapter 7: Alkyl Halides

alkyl halides

single bonds only-molecules containing a halogen atom bonded to a sp3 carbon atom

how are alkyl halides classified

primary-1 R group bonded a carbon

secondary- 2 R groups bonded to a carbon

tertiary- 3 R groups bonded to a carbon

what are the 4 halogens

F, Cl, Br, I

Match the types of halides: benzylic, aryl, allyic, vinyl

A= vinyl, B= aryl, C= allylic, D= benzylic

polarity increases what

boiling and melting point (alkyl halides are weakly polar/dipole-dipole interactions)

Chloromethane vs Dichloromethane vs Halomethane

chloromethane- produced by giant kelp and found in emissions from volcanoes

Dichloromethane- a solvent used to decaffeinate coffee

halomethane- general anesthetic

substitution vs elimination reactions

substitution- nucleophiles

elimination- bronsted-lowry bases

when a neutral nucleophile is used the substitution product bears what charge

positive (caused by a proton bonded to O or N)

what is a leaving group and what determines how strong

a leaving group is a halogen (F, Cl, Br, I)

the weaker the base the stronger the LG (I>Br>Cl>F)

what do nucleophiles and bases react with

nucleophile- reacts with C

bases- react with H and attack protons

basicity vs nucelophilicity

basicity- how readily an atom donates its electron pair to a proton(H)

nucleophilicity- how readily an atom donates its electron pair to other atoms

what makes a strong nucleophile

a strong base/a negative

(basicity increases right to left)

steric hindrance

decrease in reactivity from bulky groups

decreases nucleophilicity

how are Na+ cations and Br- anions solvated

Na+ cations- ion dipole interactions with H2O

Br- anions- strong Hydrogen bonds

Polar aprotic solvents

dipole-dipole interactions with no O-H or N-H bonding

first vs second order for nucleophilic substitution mechanisms

first order- depends on carboncation

second order-bond is broken as bond is formed

carbocation

three groups around C, trigonal planar, p orbital above and below

what happens to the rate of SN1 reaction as the number of R groups on the C with the leaving group. increases

SN1 reaction increases

how can you tell how stable a carbocation is

tertiary>secondary>primary>methyl