Principles 9 - 11

What is the ninth principle of green chemistry?

Catalytic reagents are superior to stoichiometric reagents

What is a catalyst?

A substance that increases the rate of reaction without being consumed

How do catalysts lower activation energy?

Forming bonds with reactants and bringing reactants together

What is the turnover factor?

The number of molecules converted by each catalyst site in a unit of time

What does a selectivity of 99.99% mean?

The catalyst makes one mistakes in 10,000 conversions

What does homogeneous mean?

The catalyst and reactants are in the same phase

What does heterogeneous mean?

The catalyst and reactants are in different phases

What are some advantages of homogeneous catalysts?

Intimate contact with reactants, quicker and simpler to work with

What are some disadvantages of homogeneous catalysts?

Catalyst needs to be separated after rxn, recovery is difficult

What is an advantage of heterogeneous catalysts?

Easy to separate and recycle

What are some disadvantages of heterogeneous catalysts?

Lower effective concentration, difficult to control and identify, competing side rxns

What is a phase-transfer catalyst good for?

Performing rxns between anions and organic substrates

What is a biocatalyst?

An enzyme or micro-organism that can be used as a catalyst for fine chemicals

Give two advantages of biocatalysts.

Mild rxn conditions, highly chemoselective

Give two disadvantages of biocatalysts.

Poor operational stability, higher cost

Give three common biotransformation reactions.

Oxidation/reduction, condensations, o-demethylations

Give three examples on why biotransformations are considered green.

Run under mild conditions, benign reagents, reduce number of steps

Give two reasons why a catalyst may not be green.

Turnover number is too low, precious metals used

What is the tenth principle of green chemistry?

Design for degradation

Give two examples of degradation.

Biological, physical/chemical

Name three things that help degradation.

Esters, oxygen, unsubstituted linear alkyl chains

Name three things that hinder degradation.

Halogens, nitrogen, polycyclic residues

What is the eleventh principle of green chemistry?

Real-time analysis for pollution prevention

Give four examples that require real-time analysis.

Discovery, screening, development, process control

What are two general benefits of process analytical technologies?

Increased production flexibility, reduced process variance