CHE 8B Quiz 5

Hemiacetal

OH group on anomeric carbon

Acetal

OR group on anomeric carbon

Cyclic sugars

In constant flux/equilibrium between LINEAR and CYCLIC form

Mutarotation

constant movement back and forth between three forms when in solution

Glucose

On a chair, all OH groups are equitorial (Beta-pyranose)

Alpha-pyranose

All OH groups equitorial except OH group on anomeric carbon is axial

Cyclic carbohydrates and base (NaOH)

Base pulls off H on "each" OH. Negative oxygen will add carbon groups--> turns into ethyl groups

Hemiacetal in acid and ROH

Turns into acetal. Acid protonates OH to make H2O leaving group, then ROH will attack bottom or top, making an acetal. With get both anomers (squiggly line)

Acetal with mild acid and water

Will break the acetal (OR) right next to the oxygen and turn it into an OH (with squiggly line). All other ethers will not react/change.

Two glucose molecules linked together with acetal link (glycoside bond)

Can be beta/alpha anomer. A 1,4-linked diglucose

Beta-1,4-linked diglucose

cellobiose (soluble fiber) - humans cannot digest

Alpha-1,4-linked diglucose

maltose (beer sugar) - humans can digest

Lactose (milk sugar)

A galactose and glucose linked together. Beta anomer of galactose. Galactose is axial on 4' carbon

Induction

Pull of electrons because of electronegative atom

1. Higher value of EN

2. Larger number of EN atoms present

3. Closer the EN is

pKa of Primary ROH

15

pKa of tertiary ROH

18

Industrial scale reactions

Tons of material made at once, rxns are very specific to certain molecules, avoids purification by avoiding mixtures and solvents.

Uses high temp and pressure

Laboratory scale reactions

Smaller amounts of material made, lots of purification, general patterns for functional groups, make super complex molecules

Primary alcohols in laboratory rxns

Use SN2 with primary haloalkanes

Tertiary alcohols in laboratory rxns

Use SN1/E1 with tertiary haloalkanes

Priority of COOH in IUPAC

Always #1. "-oic acid"

IUPAC name for carboxylic acid on a ring

"carboxylic acid" added at the end

Acyl halide (COX)

"-oyl halide" added at end.

Eg: 6-ethyloctanoyl chloride

IUPAC name for acyl halide on a ring

"carbonyl halideI" added at the end

Eg: 2-oxocyclohexanecarbonyl chloride

Alkyl alkanoate

Name for an ester. Has two alyl groups

Alyl (OR side) - separate group (the alkyl name goes in the beginning, followed by a space)

Alkanoate (carbonyl side) - main chain (carbonyl of the alkanoate gets #1 priority in IUPAC)

Eg: ethyl 2-ethylhexanoate

IUPAC name for an alkyl alkanoate on a ring

"carboxylate" added on the end and the alkyl group name put at the very front

IUPAC for amide

"amide" put at the end. "N-attachment" for the substituents attached to the nitrogen.

Eg: N-ethyl-N,3-dimethylbutanamide

Amide group on a ring

"carboxamide" added to the end with no spaces

Esters

Common in nature (fruit flavor, beesmax, fats)

Carboxylic acids

Common fatty acids in nature (pungeant, sharp flavors - vinegar, rancid butter, wet goat)

Nucleophilic Acyl Substitution of carboxylic acids & der(basic conditions - anion nucleophile)

Has addition and elimination of LG. Results in sp2 molecule

What happens if you have a good LG and strongly basic Nuc?

LG leaves and Nuc attaches.

What happens if you have a poor LG and weakly basic Nuc?

LG doesn't leave and there is no reaction

Nucleophilic Acyl Substitution with neutral Nuc and acid present with carboxylic acids & der

Activate E+ (oxygen picks up proton), Addition (lone pair on Nuc attaches to carbonyl), Proton transfer (LG picks up extra hydrogen on Nuc and LG leaves), Elimination (anion picks up extra hydrogen on oxygen.

Why are halogens great leaving groups and great E+

very little electron donation (overall withdraw)

Why is oxygen (in OR) an okay leaving group and an okay E+

an okay electron donor (overall donor)

Why is nitrogen a bad leaving group and a bad E+

lots of electron sharing (strong e- donor)

Acyl Halides and Nuc Acyl Sub

Is the hydrolysis of acyl halide. Happens in a few seconds. Happens with water. Has an intramolecular proton transfer.

Alcoholysis

When an alcohol breaks the acyl halide, forming an ester. Has an intramolecular proton transfer.

1 eq of an amine AND TEA (triethylamine) with an acyl halide

Halide is replaced with NH and rest of amine molecule - everything else is the same

2 eq of an amine with an acyl halide

1 eq of amine will replace the halide. The other eq of amine will react with the halide anion - turns into NH3+Cl-

Irreversible Nuc with acyl halide

LiAlH4 or RMgBr ADDS TWICE. LG leaves and carbonyl turns into OH.

Carboxylic acids do not work in base

The H on the OH gets taken away, but O- is not a LG. If there is a poor base, it attacks, but reaction reverses into starting material--> NR

Fischer Esterification with carboxylic acid and ROH + acid catalyst

form an ester- OH group turns into RO. Activate E+, addition, internal proton transfer, elimination

How to form acyl halide from COOH

Use thionyl chloride (SOCl2) and TEA to create a good LG. Double bond will attack sulfur, it will attach, halide will add to carbonyl, LG leaves

Acid hydrolysis of ester

Reverse of Fischer esterification. In presence of acid and H2O. Oxygen protonates and activagtes E+, H2O attacks carbonyl, oxygen in ring does intramolecular protonation, then bond will break at that oxygen. Ends with deprotonation.

Base hydrolysis of ester (saponification) - soap making

Base attacks carbonyl and side chain leaves.

Transesterification

Alcoholysis of ester. Initial molecule stays, Side chain will be replaced by OR group

Make amide from ester

Side chain OR is leaving group with an H now. Is replaced by RNH2 group. In presence of heat.

Ester with irreversible Nuc (LiAlH4) (RMgBr)

Irreversible Nuc adds twice. Carbonyl turns into primary ROH. Bond breaks at single bonded oxygen

Amides can make COOH

Need H2O, acid/base, heat, high temp, 24 hrs. Amide group leaves and OH replaces it.

Hydrolysis with amide

Double bonded oxygen is replaced by two hydrogens. Need heat and time. Acid/base. Can use LiAlH4

Claisen Condensation with ester

Forms Beta-keto ester, which can form Beta-ketoacids and decarboxylate (CO2 lost)

Zwitterion

charged molecule (has formal charages) but is still zero overall. Is neutral overall.