Chem 256 exam #2 (ketones and aldehydes)

suffix for naming aldehyde on alkane

change -e of alkane group to -al

suffix for naming ketone on alkane

change -e of alkane group to -one

how to name aldehyde attached to a ring formation

add carbaldehyde after end of name.

ex. cyclopentane carbaldehyde

** aldehyde is the #1 carbon

precedence of suffixes

1- carboxylic acid(oic acid)

2- aldehyde(al)

3- ketone(one)

4- alcohol(ol)

5- amine(amine)

What are the prefixes if something is a lower in precedence

aldehyde = oxo-

ketone = oxo-

alcohol = hydroxy-

amine = amino-

What is the polarity in a carbonyl group?

-the carbon has a partial positive charge

-the oxygen has a partial negative charge

What structures leads to a higher boiling point

- oxygen

- alcohols

- carboxylic acid

What makes a good nucleophile?

-excess electrons to share

negative charge or extra pairs of electrons

What makes a good electrophile?

-good at accepting electrons

carbocations, carbonyl group, and positively charged species

What are some steps in nucleophillic addition to carbonyls in basic conditions

1. nucleophile attacks carbonyl, and negative charge forms on O

2. A/B reaction occurs to convert -O to OH

What are some steps in NAC under acidic conditions

1. O of carbonyl group grabs a H+ ion

2. Nuc attacks carbon of carbonyl group and +OH becomes OH

3. A/B reaction occurs to Nuc to neutralize

What is a carbanion

a carbon that has a partial negative or negative charge

what are some ways we can form a carbanion

-attaching to MgBr

-attaching to Li

What is a Grignard reagent

R-MgBr

**R group is some side group containing C

What is an organolithium reagent?

R-Li

**R group is some side group containing C

When you add H2O a carbonyl this can be referred to as

a hydrate

nucleophillic addition to an aldehyde produces...

hemiacetal

nucleophillic addition to a ketone produces...

hemiketal

__________ are unstable unless the carbonyl and the alcohol group that formed the_________ are in the same molecule.

hemiacetal(both blanks)

** aka unless you form a ring from a string that has both component necessary

What is the formula for a carbohydrate?

CnH2nOn

mononsaccharide means

one carbohydrate

oligosaccharide means

several carbohydrates strung together

polysaccharide means

many carbohydrate strung together

triose

means 3 carbons in a carbohydrate

tetrose

means 4 carbons in a carbohydrate

pentose

means 5 carbons in a carbohydrate

hexose

means 6 carbons in a carbohydrate

ketose

a ketone within a carbohydrate

aldose

an aldehyde found within a carbohydrate

Chirality reminder

-count from largest substituent to smallest substituent

-4 substituent needs to be forward

-clockwise(R)

-counterclockwise(S)

a mirror image molecule provides

an entatiomer R and S

drawing fischer projections

-most oxidized on top

-least oxidized on bottom

-vertical lines go into page

-horizontal lines come out of the page

D stereochemical molecule

lowest OH group on chain is on the right\

(in spanish Derecha is to the right)

L stereochemical molecule

lowest OH group on chain is on the left

(L is for Left)

rule for counting possible isomers

2^n

n= chiral centers

When forming a cyclic hemiacetal where is the anomeric center?

new point of connection within the molecule

What decides alpha vs. beta product

where the OH group off of the anomeric center

-Alpha = DOWN

-Beta = UP

** the(Alpha Dog) (Beats Up) the weaker dogs

furanose

5 memebered ring with 2 double bonds and one Oxygen within ring

pyranose

6 memebered ring with 2 double bonds and one Oxygen within the ring

all natural monosacharides are __ isomers

D

hemiacetals can form form to be what size rings?

5/6

**There should only be 4/5 carbons between carbonyl group an second carbon from end of the fischer strand

how do you form ketal group for hemiketal?

add an H+ with R-OH

**O-R group attaches to old OH site

aldehyde -> _________ -> ________

hemiacetal

acetal

ketone -> _________ -> ____________

hemiketal

ketal

what are some amine nucleophiles?

-NH3

-NH2R

-NH2NH2

-NH2NHR

-NH2OH

What happens when you add a nucleophilic amine to a ketone or aldehyde group?

the carbonyl group is replaced by a double bond between the carbon and Nitrogen of Nuc.

**HAS to be acidic conditions

reduction of aldehydes and ketones

basically the carbonyl group is changed to OH and H. adding two H's to the molecule

What are good reagents for reducing aldehyde or ketone to an alcohol

-H2 with Pt or Ni

-metal hydrides(LAH, NaBH4)

**Hydrogens ATTACK!

oxidation of aldehyde

convert aldehyde to carboxylic acid

- COH becomes -COOH

what are good reagents to oxidize an aldehyde

-chromic acid (H2CrO4)

-Ag2O/NaOH

can ketones be oxidized easily?

NO