Preparation of TriH(ethynyl)benzene (DEPROTECTION METHOD)

Tri(TMS)ethynylbenzene ---------------> Tri(H)ethynylbenzene
NaOH
DCM/MeOH

1. starting material are dissolved in DCM
2. NaOH are dissolved in MeOH (*refer calculation given)
3. mix 1 and 2

*mass of NaOH = (mol of starting mat. x JMR NaOH)4

PURIFICATION STEPS

• take the reaction mixture to dryness
• dissolve the residue in DCM, wash with small amout of water
• the two layers obtained are separated in a separatory funnel
• dry the organic phase layer over MgSo4
• then, filter it using filter paper
• the volume was reduced to ~10 ml
• the product was then purified using column chromatography (follow the previous purification steps for Tri(TMS)ethynylbenzene)
• the collected orange and yellow band are subjected to rotavapor
• NMR characterization

NOTES!!

Percentage yield obtained was 114% which indicates that the product obtained contains impurities.

It might resulted from unefficiency skills of separation (trace amount of catalyst and foreign matter may still remain).

NMR proves that some peaks due to grease and at 3.797ppm (still not sure due to what compound) are present.

However, NMR clearly shows that the product obtained is the true compound.

Preparation of Trimethylsilane(TMS)ethynylbenzene

TriBrbenzene -----> TMS(ethynyl)benzene

TMSA
Pd(PPh3)2Cl2
CuI
Et3N

ref: Uhl,W.,et.al, Organometallics, 2007, 26, 2363-2369

• starting material + Et3N are placed in RBF


• apparatus are purged with vacuum, then followed by N2


• repeat purging for at least 3x to ensure no air remain in the system
  
• add Pd(PPh3)2Cl2 and CuI in the closed system


• add excess of TMSA, (refer the calculation given)

ml of TMSA = (mol of tribromobenzene x JMR TMSA x 1/density of TMSA)

• all the steps above are performed at RT


• next, mixture are heated to ~60 degrees for almost 7 hours.

MAKE SURE!!

• water tap is open during the heating for enabling the condensation to occur effectively


• put clips on joints so that none of the Et3N solvent (which are very very volatile) get evaporated, thus leaving the mixture in dry (which was exactly my mistake!)


• attach the upper part of condenser to N2 bubbler and the lower part to vacuum to make sure no moisture (from the condensation) get into the mixture


• never ever do your 1st trial at large scale, you should familiarise yourself with the methods and skills first since some of the chemicals used are quite expensive (such as Pd(PPh3)2Cl2)


• always and should never forget to close the system before adding Pd(PPh3)2Cl2 catalyst since air can actually 'kill' your catalyst (here goes your precious catalyst)

PURIFICATION STEPS

1. let the mixture to cool down


2. the mixture is the filtered off using vacuum suction to get rid of the salt


3. wash with diethyl ether


4. residue is put to rotavap and take it to dryness


5. n-pentane is added to dissolve the solid residue after rotavap


6. purication steps are then performed in column chromatography;

• almost a beaker of Al2O3 is added into column chromatography
• the Al2O3 powder need to be wetted evenly with 5%ethyl acetate/ petroleum spirit
• transfer the mixture from RBF by using pasteur pipette with extra care (do it alongside of the column to reduce the Al2O3 bed disturbance)
• carefully add 5%ethyl acetate/petroleum spirit to separate the band
• collect the desired band (dark yellowish)
• rotavap the collected solution to dryness and vacuum it to reduce all the moisture
• NMR charaterization

Percentage yield obtained = 97%

Preparation of RuCl(dppe)Cp

ref: A.G Alonso and L.B Reventos, J.Organomet.Chem.,1998, 338, 249

RuCl(PPh3)2Cp -------------------> RuCl(dppe)Cp
0.277g dppe
100 ml toluene

1. Set up the apparatus. See synthesis of RuCl(PPh3)2. (mass of RuCl(PPh3)2Cp used = 0.5085g)


2. The yellowish solution was let to reflux for about 6 hours
   
3. Next, follow the crystallization step (see previous page)


4. The filtrate volume was reduced to ~20 ml by rotavap


5. n-hexane was added into the solution (in excess)
   
6. Leave the solution which now contains precipitate in freezer for ~20 mins to allow the ppt. to settle down


7. Filter again using vacuum suction


8. The deposited ppt. at the RBF was scratched off using spatula


9. Combine all the products obtained and store in vial

RuCl(dppe)Cp

percentage yield = 46%

Synthesis of RuCl(PPh3)2Cp Part ii

So, yeah..after the vacuum line was succesfully set up..so the excitement beginnnsss...

Here is how the apparatus for the synthesis shall looks like.

Addition of the dissolved RuCl3/EtOH + Cp into the dissolved PPh3/EtOH is by dropwise within about 10 mins period of time.

After about 0ne hour of refluxing, the dark brown color of the solution will lighten to dark red-orange color as shown.

This solution is stored in a freezer at ~-10deg.celc. for an overnight.

iii. Crystallization

Next, filtration of the solution was done using vacuum suction method.



Finally, this is our precius product!!

• Percentage yield = 77%
  
• JMR = 726.3 g/mol


• Analysis = NMR, MS
  
  
  

My 1st synthesis (12 April 2010) - chloro(cyclopentadienyl)bis(triphenyl-phosphine)ruthenium(ii)

Title : Preparation of RuCl(PPh3)2Cp

Procedure

ref: Chloro(η5-Cyclopentadienyl)Bis(Triphenyl-Phosphine) Ruthenium(II): Rucl(PPh3)2(η5-C5H5)Inorganic Syntheses: Reagents for Transition Metal Complex and Organometallic Syntheses, Volume 28 , Pages270 - 272.
M. I. Bruce, C. Hameister, A. G. Swincer, R. C. Wallis, S. D. Ittel
Copyright © 1990 Inorganic Syntheses, Inc

i. Distillation of diCp -> Cp




Make sure!!

• to purge the apparatus with N2 before start distilling
• no leaking
• to attach the water inlet while distilling
• do not use water bath for the distillation, use Silicon oil instead as water can easily evaporated
• the receiver flask must be attached to an ice-containing beaker (to prevent the product to get polymerized back to diCp)
  

ii. synthesis of RuCl(PPh3)2Cp

First of all, set up the vacuum line since the compounds we are dealing with are air-sensitive.

the complete set-up of vacuum line for my bench is shown. Well, bit of messy but as long as you understand the flow, you will get it (i'm still learning).

Make sure!!

• only open the intended use of N2 inlet
• to always check for any leak of the system
• always REMEMBER to remove the N2 cylinder from the system when not in use

Next, we can start to assemble the apparatus for the synthesis. (see next)

just saying..hehe..i just loove chemistry..

this one is so hillarious!!!it reminds me of my undergrad times..don't wish to go back..:p

http://www.youtube.com/watch?v=Ekc1Xt6gMLs

comPutatioNaL cHemistry

Virtual Labs-as another way to say it..so?what was it?

Well,briefly its a new (not so new actually) way of learning and doing experimental works in lab. suitable for person who loves to do dry-lab (oohh..heaven) as compared to those tedious wet-lab jobs. For example, we have reaction of

A + B --> C + D

in usual lab, we will do the experiment of combining (or reacting) A and B that will gives a certain percentage yield of C and D. However, by using a special software (such as Gaussian03) we can now just simply predict the reaction of A and B by just key-in the compound of A and B and the result will be computationally calculated!Hwaa..i just love this madness..

However, the result generated computationally is yet not 100% precise and accurate. Thus, chem computationalist (i know..that's not in dictionary yet :p ) are still exploring this area of studies by using whole lots of compound such as organometallic, phospholipids and other more. This includes studying basis set, theory level, compounds and bla bla...(well, i don't need to memorize all,do i?)..

Well, this might only be the beginning of my blog. But, hopefully this would be as a starter for me to provide more info to myself and anyone in the same area. Why i love this topic? Well, besides the whole idea itself was so cool to me, i really hope that i can someday teach this new subject at my univ of work. It would be so much fun and helpful to my students one day..hopefully..