Chain Transfer Agent

Chain Transfer Agents


Technical brochure

2 Chain Transfer Agents

Thiochemicals and Chain Transfer Agents

� Main CTA:� n-octyl mercaptan (NOM)� n-dodecyl mercaptan (NDM)� Tertiary-dodecyl mercaptan (TDM)

� Other Light & Heavy Mercaptans� Methyl mercaptan (MM)� Ethyl mercaptan (EM)� Tertio-butyl mercaptan (TBM)� Benzyl mercaptan (BZM)� Tertio-nonyl mercaptan (TNM)

SHCH2R

SHR1

R3

R2

R1 CH R2

SH

Primary mercaptan

Secondary mercaptan

Tertiary mercaptan


� Water soluble CTA:� Thioglycolic acid TGA

� Functional CTA:� Iso-octyl thioglycolate IOTG� 2-ethylhexyl thioglycolate EHTG

� Dithio coumpounds:� 1,8 Dimercapto 3,5 dioxaoctane DMDO

HS-CH2-CH2-O-CH2-CH2-O-CH2-CH2-SH

H S C H 2 CO

O R

TGA :R = H

IOTG :R = iso-C8H17

EHTG :R = CH2-CH(C2H5)-nC4H9

Other mercaptans

Thioglycolic acid and derivatives are odorless in comparison with the other mercaptans


Europe2 R&D centers:� GRL (Lacq, F)� CRRA (Lyon, F)3 Plants:� Lacq (F),� Mourenx (F)� Rotterdam (Nl)

North America1 R&D center:� KoP (Pa)4 Plants:)� Houston (Tx)� Beaumont (Tx)� Mobile (Al)

Thiochemicals A Global Business

Asia1 R&D center:� KTC (Kyoto, J)4 Logistic Hubs:� Japan,� Singapore� Taiwan� China


Mercaptan (=Thiols) Processes

� NOM, NDM: photochemical process

� TDM: catalytic process

RCH2

H2S

hγR

SH

H2S

catalyst

S H


Specifications

≤15≤20≤15Color APHA

ClearNo turbudity or suspended matter

No turbudity or suspended matterAppearance

PotentiometryPotentiometryPotentiometry

≥98.5≥98.5≥98.5Purity (wt-%)

+ Method

≥15.6≥ 15.5≥ 21.6Mercaptan Sulfur (wt-%)+ Method

Spectrophotometer

Calculated from Mercaptan Sulfur

TDM

SpectrophotometerSpectrophotometer

ChromatographyChromatography

NDMNOMProduct


Insoluble in water (20°C)

Hydrocarbons

TDM TGANOMNDM

Solubility

Completely soluble (20°C)

Alcohols

Ethers

Practically Insoluble in water (20°C)4mg/mL

Hydrocarbons

Alcohols

Ethyl ether

Insoluble in water (20°C)<1mg/mL

Hydrocarbons

Alcohols (slightly)

Solubility parameters


OdorDetection limits of some thio compounds

Detection limit (ppb vol)

0

0.25

0.5

0.75

1

1.25

Methyl

merca

ptan

Ethyl m

erca

ptan

n-pr

opyl

merca

ptan

i-pro

pyl m

erca

ptan

n-bu

tyl m

erca

ptan

i-buty

l mer

capta

n

t-buty

l mer

capta

n

0

5

10

15

20

25

Hydro

gen s

ulfide

Dimeth

yl su

lfide

Diethy

l sulf

ide

Di n-p

ropy

l sulf

ide

Di i-pr

opyl

sulfid

e

Dimeth

yl dis

ulfide

Diethy

l disu

lfide

Ethyl m

ethyl

disulf

ide

Dimeth

yl tris

ulfide

Diethy

l trisu

lfide

Tetrah

ydro

thiop

hene

Detection limit (ppb vol)

These products smell at ppb concentrations because human nose is very sensitive to thiols.F.V. Willby, 35 persons panel

Ex: MeSHHuman Olfactory Threshold = 1 ppb = 0.001 ppmThreshold Limit Value - Short Term Exposure Limit = 0.5ppm


TDM(butadiene based copolymers)

Rubber (SBR/NBR)Latex (SB latex/XSBR)Plastics (ABS/PS)Resins (Toner/MBR)…

Main application domains of Thiols

Homogeneous BulkSolutionGas phase

HeterogeneousSuspensionEmulsion

NDMRubber (neoprene)Plastics (ABS/PMMA)

NOMPlastics (ABS/PMMA)

Reaction Medium

Continuous

Semi-continuous

Batch

Process Unit

Each process/recipe is optimized with a specific chain transfer agent.



Mechanism & Performances


Free Radical Polymerization Mechanism

MW


FRP with Chain Transfer Agent

Transfer to thiol (=mercaptan)

MW


Main CTA characteristics

� The efficiency of a chain transfer agent (CTA) is characterized by a chain constant: Ctr

� Ctr is directly impacted by the monomer (or mixture of monomers)

� Propagation rate and MW distribution are also impacted by re-initiation step

Transfer rate coefficient (ktr)

Propagation rate coefficient (kp)Ctr=

��Degradative

Transferkp<<ktr and ki<kp4

��Retardationkp>>ktr and ki<kp3

��NoneTelomerizationkp<<ktr and ki≈kp2

�NoneNormal Transferkp>>ktr and ki≈kp1

MWRpEffectKineticsCase


SBL (75/25) polymerization

0

0.25

0.5

0.75

1

0 0.25 0.5 0.75 1Monomer Conv.

RS

H C

onsu

mpt

ion

t-C8t-C12t-C14t-C16


0

0.25

0.5

0.75

1

0 0.25 0.5 0.75 1Monomer Conv.

RS

H C

onsu

mpt

ion

n-C8n-C12n-C14n-C16


0

0.25

0.5

0.75

1

0 0.25 0.5 0.75 1Monomer Conv.

RS

H C

onsu

mpt

ion

NDM

TDM

RSH characteristics

� Primary thiols are much reactive than secondary and tertiary

� The shorter the chain, the faster the transfer


New Chain Transfer Agentsfor

RAFT polymerization

Mechanism & Performances


Controlled Radical Polymerization (CRP) versus FRP

MWMW

* RAFT: Reversible Addition Fragmentation Transfer


Random Copolymerization

MWMW


MW

+

Block copolymerization

MW


Product� Formula

� RN CAS : 26504-29-0

� Purity > 95 %� Physical state: solid (mp ≈ 27-30°C)� Degradation temperature > 250°C

� Almost odorless product� Irritant

� Available for sampling or purchase� Already synthesized at pilot scale

DiBenzylTriThioCarbonate (DBTTC) for RAFT Polymerization

S

S

S

Registration

� ELINCS registration(done for V<1T)

� And outside E.U. zone(on request)

� TSCA registration (on going)

Legal part

� Arkema holds IP patent rights (license + sub-license) for the use of RAFT agents in some specific polymerization processes and their applications

� Product available under secrecy agreement

Under development at Arkema


Thiochemical Innovators

Our technological expertise

� Sulfur chemistry synthesis starting from S, H2S,NaSH or CS2

� Application knowledge in refining, steam-cracking, polymerization, gas odorization, metal plating, mining and lubrication

Our lab tools

� Analytical means especially developed for Thiochemicals and heavy general analytical capabilities

� Olfactometric laboratory to help your address issues linked to odors in your application

� Application testing equipment: flotation cell, polymerization equipment, plating cells,tribological testing tools, polymer characterization, steam cracking andhydrotreatment lab pilots…

Our industrial development equipment

� Arkema operates several pilot and multi-purpose plants managed under ISO9001 and ISO14001 standards, with a total reactor capacity exceeding 75m3, either glass-lined or stainless steel

� These facilities, staffed with senior scientist, engineers and project managers, can apply a large range of reactions and process capabilities

� They allow Arkema a fast scale-up of new molecules from the lab to industrial production

Address us your request for new CTA

Documents

Chain Transfer Agent