Acetals, Hemiacetals, Imines and Carbonyl/"Waterfall" Reactions

what are acetals and hemiacetals?

the linkages that hold polysaccharides together

what is the structure of a hemiacetal?

has an alcohol and an ether

what is the structure of an acetal?

doesn't have an OH - instead of the H connected to oxygen, another R group is connected to it; the rest of the structure is the same as a hemiacetal

what is the reagent used in a hemiacetal reaction?

catalyzed H+ and HO-R3

what direction are hemiacetals generally favored?

the reverse direction (towards the reactants)

what direction are hemiacetals favored if they are cyclic?

the forward direction - towards the products

what will the reactant be for a hemiacetal or acetal reaction?

aldehyde or ketone

what is the reagent for an acetal reaction?

catalyzed dry H+ and 2 equivalent of HO-R3

what is the difference between acetals and hemiacetals?

in acetals, 2 new O-R groups are added

what direction is favored in the acetal reaction?

the forward direction in the presence of water - towards product

how many steps are in the mechanism for a hemiacetal reaction?

3 steps

are alcohols good nucleophiles?

no

what is the first step in a hemiacetal or acetal reaction?

make a better electrophile by having the oxygen take the catalyzed H+ proton

how many steps are in the acetal mechanism reaction?

7 steps

what is the last step for the acetal reaction?

lose the proton

what is the removal of acetal reaction?

the backward reaction - end with a double bonded oxygen to an R group

what are the reagents used in the formation of imines?

catalyzed dry H+ and H2N-R group

what is the reactant you start with in an imines reaction?

ketone or aldehyde

is amine a weak or good nucleophile?

weak nucleophile

what is the first step of an imine reaction?

make the aldehyde/ketone a better electrophile by taking the catalyzed H+ proton

what ultimately happens in an imine reaction?

N replaces O and has a double bond to the original structure

what is reductive amination?

reducing imines - N doesn't have a double bond

what reagents are used in reductive amination?

1. catalyzed dry H+, H2N-R
2. H2, Ni or 2. NaBH4 3. H3O+

what reagent is used in carbonyl/waterfall reactions?

a nucleophile - carbonyl groups

what are the carbonyl groups?

acid chloride, anhydride, ester, amine, carboxylic acid

what does a carbonyl reaction form at some point?

tetrahedral intermediate

what is the most reactive carbonyl functional group and so is at the top?

acid chloride

what is the least reactive carbonyl functional group and so is at the bottom?

carboxylic acid

what is the order of carbonyl groups from top to bottom?

acid chloride, anhydride, ester, amine, carboxylic acid

how do you get from a carboxylic acid to an ester?

fisher esterification

what is the reagent you use to get from a carboxylic acid to an acid chloride?

SOCl2

what is the reagent you use to get from a carboxylic acid to an ester?

catalytic H+, R-OH

what is the reagent used to get from an acid chloride to an anhydride?

carboxylic acid

what is the reagent used to get from an acid chloride to an ester?

alcohol

what is the reagent used to get from an acid chloride to an amine?

amine

what is the reagent used to get from an acid chloride to a carboxylic acid?

water

for an acid chloride reaction, what is different than the other carbonyl reactions?

you have to use 2 equivalents of the reagent or a pyrimidine for the second step

what is SOCl2?

thiomylchloride