Page 167 - CW E-Magazine (12-3-2024)

Special Report

per mol) and the activation energy is 43 T. Yang et al have given a very com- Alkylation reactions are covered, e.g.,
KJ per mol. The global production of P is prehensive coverage of MRT, giving Naphthalene + long chain alkenes;
12-mtpa and by 2030 it will be 18.6-mtpa. a variety of examples of considerable dodecyl benzene sulfonic acid is also
The reaction is free from mass transfer industrial importance. Hazardous re- covered.
limitation. The temperature was varied actions like nitration, rearrangement,
from 300°K to 500°K and explosive cycloaddition, diazotisation, coupling, Combined with online analysis and
limits were avoided. The simple laboratory alkylation, sulfonation, etc. are very well intelligent algorithms, MRT can play
set up is referred. (Reaction Chem. Eng., performed through MRT, which can han- a very important role. (J. Chem. Eng.
2023; DOI: 10.1039/D3Re003554J). dle high exothermicity as well. Even high Japan, 2023, 56, No. 2197011; DOI;
pressure reactions can be catered. Many 10.1080/00219592.2023.2197011).
Reengineering of the car- of the above reactions are now carried Mixing intensifi cation and kine-
bon-to-acetylene process fea- out in batch reactors, which have poor tics of 2,4-difl uoronitrobenzene
turing negative carbon emission performance of mixing and heat transfer. (DFNB) homogeneous nitration

M. Li et al have covered this subject, Many examples are covered in this reaction in a heart shaped con-
which gave birth to Reppe Chemistry extensive article. Hofmann rearrangement tinuous-fl ow microreactor
based on using acetylene for a range of (HR), which converts primary amide to S. Guo et al have reported intensifi cation
very important products on a large scale primary amine with one less carbon. This of liquid mixing in the heart-shaped
based on calcium carbide hydrolysis, reaction is relevant even in making APIs: microreactor and have mixing improved
which is energy-intensive and gives a oseltamivir, epibatidine, gabapentin by three orders of magnitude compared
large amount of solid industrial waste. (G), etc. In the case of G, 1,1-cyclo- to the capillary T-micromixer. Thus,
These authors have come out with a new hexanediacetic monoamide is converted conversion rate of 98.5% was realised
with a reduction in residence times by
two orders of magnitude, compared to
batch reactors. Interphase mass transfer
resistance was eliminated. DFNB is an
intermediate for a very effective herbi-
cide, fl umioxazin. (Chem. Eng. Jl. 2023,
477, Dec., 147011; DOI: 10.1016/j.
cej.2023.147011).
Low-temperature solid com-
bustion technology of biomass
for pollution reduction: Poten-
tial and necessary fundamentals
strategy based on BaCO – Ba(OH) – to G. This reaction is also important in X. Li et al have worked on the title
3
2
BaCO looping where BaC replaced cyclopropylamine. (HR can also be used synthesis of great relevance in Northern
2
3
CaC . BaC manufacture has faster to make isocyanates in biphasic system India. These authors have commented that
2
2
kinetics, lower formation temperature with 2° and 3° amides). high temperature of solid combustion
and there will be no CO release. This in modern combustors leads to serious
2
is a promising platform. (Green Chem., Diazotisation and azo-coupling reactions pollution. These authors have worked
2023; DOI: 10.1039/D3GC01775C). are covered for making a variety of dyes on low-temperature combustion tech-
and pigments. High yields & pigment
Fundamentals and develop- quality are realised, e.g., Pigment Red 146. nology, which applies low temperature
for solids, but normal temperature for
ment of micro reaction techno- Cycloaddition and epoxidation reactions gas during combustion. The reduction
logy (MRT) for the application are covered. An interesting example in pollution has been analysed. Their
of fi ne chemicals synthesis is that of styrene to its epoxide using analysis shows that for straws more than
[This column has covered several acetonitrile + H O to give CH (C=NH) 60% of deposit and particle emissions
2
2
2
papers on MRT, particularly for nitration, OOH, which carries out epoxidation. can be reduced and 100% of ash can be
diazotisation, etc.] Cyclic carbonates are other examples. recycled when the solid temperature is
Chemical Weekly March 12, 2024 167

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