Prelim Exam 2: Sulfur Compounds; Aldehydes and Ketones; Carboxylic Acids, Carboxylates, and Nitriles; Multistep Synthesis; Polymers and Cyclic Compounds (Chem 322- Organic Chemistry) Flashcards
thiols
R-SH
mercapto group
-SH group
thiol nomenclature
name parent alkane and add “thiol” to the end of the name
sulfide nomenclature
named as “sulfide” compounds: alkyl sulfide or alkyl-thio alkane
sulfide
R-S-R
thiol preparation
from alkyl halides through Sn2 displacement with sulfur nucleophile such as SH- anion (works poorly unless excess SH is present due to competing Sn2 reaction with alkyl halide to give sulfide as by-product); using thiourea works better
thiol reaction
2 R-SH oxidized by Br2 or I2 to yield disulfides (R-S-S-R)
sulfide preparation
treatment of thiol with base gives thiolate ion (RS-) which undergoes reaction with primary or secondary alkyl halide [R-SH –1) NaH 2) R-X –> R-S-R]
sulfur compounds are more nucleophilic than ethers
because electrons are farther from the nucleus and less tightly held than those on oxygen
sulfide reactions
dialkyl sulfides react rapidly with primary halides by Sn2 to give sulfonium ions (R3S+) – which are useful alkylating agents because a nucleophile can attack one of groups bonded to positively charged sulfur to displace a neutral sulfide as leaving group……. oxidation of sulfide with H2O2 to yield sulfoxide (R2SO) with further oxidation of sulfoxide with peroxyacid yielding a sulfone (R2SO2) [ R-S-R –H2O2–> RSOR –CH3CO2H–> RSOOR]
DMSO (dimethyl sulfoxide)
common polar aprotic solvent
spectroscopy of ethers
infrared spectroscopy– absorption due to C-O single bond at 1050-1150 cm^-1… NMR spectroscopy– H NMR absorptions in 3.4-4.5 delta region for H on carbon next to O in ether and epoxide hydrogens absorb at 2.5-3.5 delta region
1) NaH 2) RCH2X
williamson ether synthesis from primary alcohols to form ethers
1) ROH, (CF3CO2)2Hg / 2) NaBH4
alkoxymercuration/demercuration from alkene to form ethers
HX, H2O
cleavage of ethers by HBr or HI to form an alkyl halide and alcohol
H3O or HBr
acid-catalyzed epoxide opening to yield a diol or an alkyl halide alcohol
RO-, ROH or 1) ether / 2) H3O+
base-catalyzed epoxide opening to yield a alkyl ether alcohol or a primary alcohol
1) (H2N)2C=S / 2) H2O, NaOH
reaction of alkyl halide to yield thiol
I2, H2O
oxidation of 2 RSH to yield disulfide (R-S-S-R)
RS- + alkyl halide
yields sulfide (R-S-alkyl)
H2O2
oxidation of sulfides to sulfoxides
RCO3H
oxidation of sulfides to sulfones
sulfoxide
R2S=O
sulfone
R-SO2-R
sulfonic acid
SO3H
sulfuric acid
H2SO4
dialkyl sulfate
R2SO4
nucleophile
nucleus loving; attracted to positive charge… has a negative charge, a partial negative charge, or a pi bond… provides pair of electrons to form bond
electrophile
electron loving; attracted to negative charge… has positive charge, a partial positive charge, or a leaving group… accepts pair of electrons to form bond
deprotonates phenols
NaOH or NaH
deprotonates alcohols
NaH
aldehyde nomenclature
replace “e” of parent name with “al”; no number necessary because aldehydes are always carbon 1 and must always be in parent chain; cyclic aldehydes are named with suffix “carbaldehyde” on end of parent name
nomenclature ending priority
carboxylic acid > nitrile > aldehyde > ketone > alcohol > alkyne > alkene > halogens, alkyl, alkoxy
ketone nomenclature
replace “e” ending with “one”; no number if ketone can only be in one position in a parent chain; numbering of parent chain begins at end closest to carbonyl carbon; locant must be used with ketone name
acyl group
RC=O
formyl group
HC=O
acetyl group
CH3-C=O
benzoyl group
benzene-C=O
benzyl group
-CH2-benzene
1) RCOCl / 2) AlCl3
friedel-crafts acylation to convert a benzene into a phenyl ketone
HgSO4, H2SO4, H2O
conversion of alkynes into ketones
DMP, PCC or KMnO4 or CrO3
oxidation of secondary alcohols to ketone
1) O3 / 2) Zn, H+
ozonolysis of alkenes to yield a ketone or aldehyde
R2CuLi, -:R
reaction of cuprates with acid chlorides to yield ketones
DMP or PCC
oxidation of primary alcohols to yield aldehydes
1) BH3 / 2) H2O2, -OH
hydration of terminal alkynes to yield an aldehyde
1) DIBAH / 2) H3O+
partial reduction of esters to yield an aldehyde and an alcohol
carbonyl group
C=O
carbonyl characteristics
carbonyl carbon sp^2 hybridized and forms 3 sigma bonds and 1 pi bond… planar about double bond and have 120 degree bond angles… carbon-oxygen bond is strongly polarized because of high electronegativity of oxygen relative to carbon (carbonyl carbon acts as electrophile and carbonyl oxygen acts as nucleophile)… electron withdrawing group
oxo
name of ketone functional group substituent when other priority groups are in the compound
aldehydes are generally more reactive than ketones in nucleophilic addition reactions
because there is less steric crowding from large substituents and because a primary carbocation is higher in energy and thus more reactive
aldehydes/ketones + carbon nucleophile
yields alcohol
aldehydes/ketones + nitrogen nucleophile
yields imine
aldehydes/ketones + oxygen nucleophile
yields acetal
Wolff-Kishner Reaction
treatment of aldehyde/ketone with hydrazine (H2NNH2) in presence of KOH to yield an alkane (through intermediate hydrazone intermediate (R2C=NNH2)
acetal
R2C(OR)2; formed upon reaction of aldehydes/ketones with 2 equivalents of alcohol; act as protecting groups for aldehydes/ketones and can be removed with H3O+
hemiacetal
R2C(OH)OR; formed upon reaction of aldehydes/ketones with 1 equivalent of alcohol
carboxylic acid
RCOOH