1) R-NH2 ->R-N=C=S

2) R-N=C=S + R'-SH -> R-NH-C(=S)-S-R'

Because free amine react with thiocyanate, protection is needed.

If you have polyethyleneimine -(-NH-CH2-CH2-)n-, trick is impossible. In the case of H2N-(-CH2-CH2-)n-NH2 (really polyethylene diamine) - it is possible

Thank you for your valuable comment. I am sorry for the wrong compound which I have mentioned earlier. It is Polyethyleneglycol diamine. Please tel me how this can be interacted either by covalent or ionic between these two compounds such as thiol and PEG-diamine.

Hope my question is clear.

Thanks is illegal on ResearchGate, legal currency is UpVote :-)

R= H2N-CH2-CH2-O-(-CH2-CH2-O-)n-CH2-CH2- in corrected answer

Can you explain it by more detailed manner. In this how thiol would get reacted..??

1) H2N-CH2CH2-PEG-CH2CH2-NH2 -> S=C=N-CH2CH2-PEG-CH2CH2-N=C=S

2) S=C=N-CH2CH2-PEG-CH2CH2-N=C=S+ R'-SH -> R'-S-(S=)C-NH-CH2CH2-PEG-CH2CH2-NH-C(=S)-S-R'

First reaction is synthesis of isothiocyanate from amine (from thiophosgene, for example)

Second reaction is nucleophilic addition of thiol to isothiocyanate (need catalytic amount of base, so cysteine in salt form. Product is dithiocarbamate, deprotection by acid.

I have not exact procedures in hand but it is student-level chemistry available anywhere.

P.S. Info for newcomers - all synthesis protocols (including mild deprotection) see in below messages

Yeah .. Finally it would lead to form a disulphide right ??

No, it will parent R'-SH , salt of amine and COS (carbon oxosulphide)

I think the book that may help is Synthetic Organic Chemistry in addition to the valuable directions and information given by Dr Andrei.

Dissulfide disulfide can be done on ultrasound with a tertiary amine in 30 minutes at 29 degrees in the search siencfinder !

Dr. Hatem.... Can you tel me more details about the book..?

Thankyou for the comment Mr. Paiva.. I will try forming the reaction.

Dear Dr Narasimhan

The details of the book is

Practical Synthetic Organic Chemistry: Reactions, Principles, and Techniques

Stephane Caron (Editor)

ISBN: 978-1-118-09356-6

898 pages

July 2011

New synthesis of isothiocyanates:

http://www.organic-chemistry.org/synthesis/C2N/isothiocyanates.shtm

Moderate yield but very simple synthesis.

In attachment see synthesis from thiophosgene and best known simplest high-yield synthesis

S=C=N-PEG-N=C=S is absent in SIGMA-ALDRICH Catalog, so you can sell this very valuable linker.

And

Message window accept somewhat one attachment per run so send you separately

Addition of R-SH to RNCS

Dear Dr. Andrei and Dr. Hatem.. Thank you for giving me such as valuable information. I got some solution for my next synthesis part.

Dear Narasimhan

You are very welcome

Yours Sincerely

Hatem Maraqah

See the attached article:

You can attach an amine to a thiol with AMAS, a Crosslinking reagent that has both a maleimide and n hydroxy succinamide group.

@Marcia Moss

AMAS is too shot linker - discussion of problems linked with linkers :-) see at https://www.researchgate.net/post/Why_dont_biotinylated_nanoparticles_bind_to_streptavidin_functionalized_nanoparticlesev=prf_cont_person_add_comment_question_target

ALDRICH Catalog contain many bifunctional PEG-linkers, but with permanent (non-removable in mild conditions) linking :

http://www.sigmaaldrich.com/chemistry/chemistry-products.html?TablePage=16281423

http://www.sigmaaldrich.com/materials-science/material-science-products.html?TablePage=20330418

Thank you Andrei for the info. I have never used AMAS. It may work better win small molecules and proteins rather than nanoparticles?

I think "yes". Rare examples, wich may be exist, are more exclusion than rule . http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2974592/ - AMAS was applied, but after PEG 5000 modification of nanoworm.

I am not sure that so long PEG 5000 is needed, because shorter PEG work good too, for example, TentaGel supported reagents http://www.rapp-polymere.com/index.php?id=73 .