Ultrasound as a green reactor

GREEN CHEMISTRY

Seminar

Presented by:

Supervisor: Assoc. Prof. Dr Nam Thanh

Son Phan

Contents Introduction

Sound wave and ultrasound Applications of ultrasound in industry

and chemistry, and ultrasound apparatus Power of ultrasound: Acoustic cavitation Effects of ultrasound on reactions

4/12 Green principles are adapted Researches on ultrasound-assisted

reactions Conclusion

SOUND WAVE AND ULTRASOUND1

Industrial applications of ultrasound2

Ultrasound apparatus

ultrasonic cleaning bath

2

ultrasonic horn

Ultrasound apparatus2

THE POWER OF ULTRASOUND3

THE POWER OF ULTRASOUND3

ACOUSTIC CAVITATION

“Cavitation is an extraordinary method of concentrating the diffuse energy of sound into a chemically usable form”.

Kenneth Suslick

3

ACOUSTIC CAVITATION

Cavitation• The formation, growth, and implosive

collapse of bubbles in a liquid• Cavity growth depends on many factors (f,

T, t,. etc).Types of cavitation

Stable Cavitation • The bubbles oscillate

around their equilibrium position over several refraction/compression cycles

Transient Cavitation • The bubbles grow

over one (sometimes two or three) acoustic cycles to double their initial size and finally collapse violently

• Rectified diffusion

Rectified diffusion

• During oscillations of cavities, the amount of gas or vapor that diffuses in or out of the cavity depends on the surface area, which is slightly larger during expansion than during compression.

3

Radical effectsMechanical effects Electrochemical

Temperature

Intensity

Frequency

Solvent

Gas type and contentExternal applied pressure

US

FACTORs AFFECT AFFECTs FACTORs ???

Effects of Ultrasound

Physical Effects • The hot-spot

theory• Shear forces, jets

and shock wavesChemical Effects • Radical effects• Mechanical effects • Effect on

electrochemical processes

4

HOMOGENEOUS LIQUID-PHASE REACTIONS4

CAVITATION NEAR A SURFACE4

HETEROGENEOUS POWDER-LIQUID REACTIONS4

HETEROGENEOUS LIQUID-LIQUID REACTIONS (EMULSION)4

1 • Prevent waste

2• Use safer

solvents and reaction conditions

3 • Increase energy efficiency

4 • Minimize the potential for accidents

4/12 green principles

may be adapted by using

ultrasound

5

RESEARCHES ON ULTRASOUND-ASSISTED REACTIONS

6

“Ultrasound-promoted synthesis of quinolines using basic ionic liquids in aqueous media as a green procedure” 

Elaheh Kowsari, M. Mallakmohammadi. 2011

Effect of the ultrasonic irradiation time and the ultrasonic frequency on the substituted quinoline yield

The ultrasonic irradiation time had significant effect on the condensation, when the amount of BIL1 (0.5 mmol) and the ultrasonic frequency (50 kHz) were kept constant. At 1, 1.5, and 2 h, quinoline (3a) was obtained with 40%, 65%, and 95% GC yields, respectively.

“Ultrasound-promoted a green protocol for the synthesis of 2,4-diarylthiazoles under ambient temperature in [bmim]BF4”  

Jalil Noei, Ahmad Reza Khosropour. 2009

A simplified green chemistry approaches to synthesis of 2-substituted 1,2,3-triazoles and 4-amino-5-cyanopyrazole derivatives conventional heating versus microwave and ultrasound as ecofriendly energy sources  

Khadijah M. Al-Zaydi. 2009

Conclusion

As increasing environmental consciousness in chemical research

and industry, the challenge for a sustainable environment calls for

clean procedures. Ultrasonic-assisted organic synthesis (UAOS) as

a green synthetic approach is a powerful technique that is being

used more and more to accelerate organic reactions

Notable features of the ultrasound approach are enhanced reaction

rates, formation of purer products in high yields, easier

manipulation and considered a processing aid in terms of energy

conservation and waste minimization which compared with

traditional methods

[1]. Timothy J. Mason, John P. Lorimer, Applied sonochemistry: Uses of power ultrasound in chemistry and processing, Wiley-VCH Verlag GmbH, Weinheim, 2002.

[2]. Mukesh Doble, Anil K. Kruthiventi, Green chemistry and processes, Elsevier, Oxford, 2007.

[3]. Elaheh Kowsari, M. Mallakmohammadi, Ultrasound promoted synthesis of quinolines using basic ionic liquids in aqueous media as a green procedure, Ultrasonics Sonochemistry, Volume 18, Issue 1, January 2011, Pages 447-454

[4]. Khadijah M. Al-Zaydi , A simplified green chemistry approaches to synthesis of 2-substituted 1,2,3-triazoles and 4-amino-5-cyanopyrazole derivatives conventional heating versus microwave and ultrasound as ecofriendly energy sources, Ultrasonics Sonochemistry, Volume 16, Issue 6, August 2009, Pages 805-809

[5]. Jalil Noei, Ahmad Reza Khosropour, Ultrasound-promoted a green protocol for the synthesis of 2,4-diarylthiazoles under ambient temperature in [bmim]BF4, Ultrasonics Sonochemistry, Volume 16, Issue 6, August 2009, Pages 711-717

References

Appendix 1: Effect of temperature

Appendix 2: Effect of Intensity (or PA)

Appendix 3: Effect of frequency and time

Appendix 4: Effect of solvent

1. VISCOSITY

2. VAPOUR PRESSURE

Appendix 5: Effect of gas type and content