Furoin Condensation (Final)

What was the purpose of this lab?

Use biocatalysis for C-C bond formation with nucleophilic addition while using renewable resources

How was low toxicity and renewable feedstocks green chemistry used?

By using corn cobs

How was catalytic processes green chemistry used?

By using Thiamine/Vitamin B1 as a catalyst

C=O is a __ covalent bond.

Polarized

__ add to carbon of C=O bonds, __ occurs on oxygen.

Nucleophiles add, protonation occurs

In the polarized bond what are the partial charges?

Partial negative oxygen, partial positive carbon

Organolithium addition reagents

1) CH3Li — CH3 nucleophile
2) H2O — hydrolysis

Grignard addition reagents

1) CH3CHO — electrophile
2) H2O — hydrolysis

What is the nucleophile and electrophile in a grignard addition?

The grignard (MgBr) makes a nucleophilic C, the C=O is the electrophile

Benzoin condensation reagents

NaCN (nucleophile), aqueous ethanol (hydrolysis)

Mechanism for benzoin condensation

Nucleophilic attack of ^-CN at C=O, alkoxide proptonation, base deprotonation at former C=O forms anion, anion nucleophile attacks another molecule of electrophilic C=O in starting material, protonate new alkoxide, deprotonate first hydroxy forms C=O to lose CN **racemic mixture product

Thiamine/Vitamin B1

Biocatalyst for C-C formation, written as [Th]:

Furoin condensation starting material

Furfural

Furoin condensation product

Furoin (racemic)

What are polymers?

Large molecules, or macromolecules, composed of many repeating units

What are proteins?

Polymers of amino acids, linked by amide bonds

What are complex carbohydrates?

Polymers of sugars, linked by acetal bonds

Process of xylan conversion

In acidic conditions the acetal linkages of xylan in the corn cobs are hydrolyzed producing xylose, distillation of xylose converts it to furfural

Simple distillation

Heat source

Simple distillation

Ice bath

Simple distillation

Water inlet

Simple distillation

Water outlet

Simple distillation

Condenser

Simple distillation

Distilling flask

Simple distillation

Receiving flask

Simple distillation

Distillation head

We made __ from a locally abundant biomass resource —> __.

Furfural from corn cobs.

Thiamine/Vitamin B1 was used with furfural for __ __ of a carbanion to an aldehyde in order to produce furoin.

Nucleophilic addition

Compounds produced in bulk (renewable feedstocks) examples

Plants like starches or vegetable oils

Starches or vegetables usually contain 1 and 2.

1) multiple functional groups
2) stereogenic centers

Petroleum-based (non-renewable) feed stocks are mostly __ hydrocarbons lacking __ __ or __ __.

Saturated lacking functional groups or stereogenic centers.

Biomimetic catalyst

A compound that mimics a catalytic function found in nature (ie. thiamine)

What is needed to produce furfural?

Heating in the presence of an acid

What is the monomer of xylan?

D-xylose, that can be turned into furfural from distillation, acid, and heat

When carbanions from an aldehyde and nitrile react with another aldehyde it is called __ __.

Benzoin condensation

Umpolung

Reversal of polarity (ie. C=O usually has partial positive carbon, but reversal makes that carbon the anion)