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Author: Subject: PETN synth
Microtek
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[*] posted on 27-4-2008 at 23:44


OK, this is the last OT post from me then: I titrated with NaOH soln at about 1 M IIRC. The NaOH concentration had been established precisely by titration against high purity benzoic acid. I calculated the accumulated error based on estimates of the individual errors and got a concentration of 99.5 +- 0.1% IIRC.
I have an old Mettler-Toledo mechanical balance which is very accurate. It measures down to 0.0001 g with excellent repeatability and was mine for the taking, simply because the lab upgraded to digital versions. It enables me to do fairly accurate work at the small scale, where I prefer to be.

Anyway, the product of the PETN synthesis using only 2.5 ml HNO3 for 1 g PE produced 2.250 g product after thorough neutralisation (in solution) and washing.
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[*] posted on 28-4-2008 at 09:40


Did you get a melting point? This would give pointers to whether it contained lower nitrates. On the other hand, if it contained much trinitrate of lower molecular weight the yield would be over 100%....

97% seems high anyway, I don't have numbers for PETN here, but I remember for NG even industrial 1000kg batches using 99% nitric with oleum get below 97% for NG. IIRC mostly because the spent acid dissolves 3%, though 2/3 of that *could* be recovered by solvent extraction, which is *not* done in normal practice. They want to get rid of the shit ASAP.

You sure the solvent from neutralization was completely gone (i.e. vacuum desiccator)? I remember a batch of MHN containing considerable solvent even though it looked and felt dry. The much lower mp showed it.

Not that I don't want you to hold that yield record - I am content to have beaten you with the RDX yield (additive threat). ;)

[Edited on by Boomer]
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[*] posted on 29-4-2008 at 00:14


I didn't measure the melting point of the product as I don't have an actual melting point apparatus. So every time I need to do a measurement I have to come up with some improvised contraption. That said, I did place samples of different PETN batches on a thin glass plate which was then placed on a hotplate. The samples all melted practically simultaneously and very sharply. They also crystallized in a manner which suggested a high-purity sample.

Regarding the RDX, my best yield was 74% of theory based on hexamine, but more impotantly (in my opinion) 0.31 g RDX per ml of HNO3. I don't quite recall what your numbers were....
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[*] posted on 8-5-2008 at 07:51


Back on topic: this friday I will post a synth that I have used for PETN. I got it in a torrent and it is very good and contains good data on PETN. I got my pentaerythritol through good social engineering but the supplier no longer carries it.

PETN Is a very safe and good explosive in my opinion but I prefer ETN for the simplicity of obtaining the precursors and synthesising it in uncontrolled conditions. I hate said a lot on ETN on roguesci but it is down.




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[*] posted on 15-12-2008 at 11:09


Quote:
Originally posted by Microtek
OK, this is the last OT post from me then: I titrated with NaOH soln at about 1 M IIRC. The NaOH concentration had been established precisely by titration against high purity benzoic acid. I calculated the accumulated error based on estimates of the individual errors and got a concentration of 99.5 +- 0.1% IIRC.
I have an old Mettler-Toledo mechanical balance which is very accurate. It measures down to 0.0001 g with excellent repeatability and was mine for the taking, simply because the lab upgraded to digital versions. It enables me to do fairly accurate work at the small scale, where I prefer to be.

Anyway, the product of the PETN synthesis using only 2.5 ml HNO3 for 1 g PE produced 2.250 g product after thorough neutralisation (in solution) and washing.


I've also tried nitration using 99.7% HNO3 (yellowish - some NOx exist), to get rid of nitrogen oxides i've added some small ammount of urea until acid is completely colorless. Temperature was carefully controlled to be below 15C, but at some moment (then about half of penthaerythrytol was added to acid) violent oxidation started and mixture was emidately poured into large ammount of ice cold water - no precipitate was obtained. Next attemt i've made was dilute (70%) nitric acid + conc. H2SO4 using proportions mentioned in this tread somethere above, temperature was controled by stream of cold water, all was fine until moment close to the end of penthaerythrytol addition, a was away for 15 sec to turn off lights in my bedroom (flask was sitting in cooling bath), again violent oxidation took place, many NOx evolved, temperature rised from ~12C then i was away, to 56C+ then i came back after ~15 seconds, reaction mixture turned into black oily liquid, with was emidately poured into ice water and discarded (nitric acid used was just 99.5% HNO3 diluted by water to 70%). Third attempt was made using same method as in second, but temperature control was to below ~10C and virgous stirring without stops, after all penthaerythrytol was added, and mixture is allowed to slowly heat to room temperature at ~20C violent oxidation was started, and mixture is also poured into large ammount of cold water, some NOx evolved and precipitate of PETN is obtained with ~30% yield. I have no idea how you mean to stop this violent oxidation reactions, and how you never encountered them. Somebody have any idea what is the problem here?




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[*] posted on 15-12-2008 at 18:18


Yeah I have studied this nitration a bit and worked out
a pretty optimal synthesis which is basically identical to a patented method. I am sure I posted about it, maybe it was on another forum, the E&W forum. I'll have to go back and check this to get the specifics. But as I recall
the nitration is a very high yield reaction with high acid utilization efficiency using ~97% HNO3 alone, but it is also a very very exothermic nitration where excellent cooling and very slow addition of the pentaerythritol is required
while good stirring and a narrow nitration temperature range is closely controlled by rate of addition. It can be nailed and reproduced because I have done it more than once with identical results and no complications. But it does require careful work. It was based on one of the
old patent Nobel or DuPont processes I think. I do remember the nitration proceeds at a mild cool temperature absent any of the warming described with some other methods...which is a really bad idea IMO .

Okay I found it, what you are looking for of course is
Rosco's good old country recipe for PETN :D

http://www.sciencemadness.org/talk/viewthread.php?goto=lastp...

Hmmm I just went back and saw that Sickman posted this same link about eight months ago, so this puzzles me what could be the problem unless there is some variable which was not observed, and this accounts for the problem.
Anyway it worked for me very well as described.

[Edited on 15-12-2008 by Rosco Bodine]
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[*] posted on 16-12-2008 at 12:21


Process with 70%HNO3 + conc. H2SO4 was repeated by another russian chemist using conc. HNO3 diluted to 70%. Same problems vere encountered, it was very surprising, because, man i'm talking about reported several completely successfull runs using this method, he also mentioned that he has no idea about what is the reason of problem. There is something terribly strange here, only difference from my case with ~15 sec away time, he was away for about 40 seconds.

[Edited on 16-12-2008 by Engager]




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[*] posted on 17-12-2008 at 02:14


An educated guess is that your problem is related to two factors...reaction temperature too low and addition not gradual enough to be in sync with the reaction rate, causing surging. You need a sufficient reaction temperature and good stirring so that there is a smooth reaction of added material without any delay or induction period, because the reaction is thermally driven but is also extremely exothermic, so a runaway is lurking there for any unreacted material, proceeding to react and cascading past the decomposition temperature. This is classic organic nitration stuff. The first thought is there is insufficient cooling so the reaction temperature is lowered which then makes the reaction sluggish for added material and aggravates the inclination for induction delay followed by runaway. So it may seem conterintuitive, but your baseline nitration temperature needs to be raised a little so that added precursor nitrates smoothly on addition as soon as it is introduced, without any delay which allows unreacting material to accumulate, and to then react in a self-accellerating fashion.

And yeah the problem is aggravated with a more oxidizing nitration mixture using mixed acids. The straight nitric acid
nitration method is really the best method for PETN.

Try that five degree window temperature range I described
for 18-23C using the 97% HNO3. The idea there is to sprinkle
in the PE very slowly at 18C and at a rate to keep the reaction temperature in that range, allowing for a rise to 23C
from the exotherm of each addition, allowing the exotherm to subside and making the next addition at the fall again to18C. If you have a screw feed addition funnel for solids, you can probably fine tune the rate of addition to flatten the oscillation of temperature a bit better than that 5 degrees.

The exact optimum temperature is somewhere in that range,
perhaps 20-22C, I am not certain. But the warmer you run
it , while it goes faster, it is closer to the limit and has less
headroom range for tolerating any surges in temperature.

It has been a few years since I did this nitration, but I tend to make accurate notes, so those numbers are probably correct.


[Edited on 17-12-2008 by Rosco Bodine]
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[*] posted on 17-12-2008 at 08:00


Here is the document Microtek vas talking about :

http://www.2shared.com/file/4476387/87867b1c/petn2.html

Page contains some ads and popups.... just ignore them and click:
"Save file to your PC: click here" on the right bottom corner of the page.

You have to enable macros in M$ Excel in order for this document to work.


how to read results:

Area I - Formation of PETN with yield of 94-98% without formation of sulfoesters.
Area II - Formation of PETN via sulfoesters.
Area III - Area of low yields (10-50%) due to the high NOx
production and oxidation processes
Area IV - PETN not forming"


The only problem with nitration of PE with mixed acid I had, was localized overheating and oxidation because concentration of water rose to 30% at that spots. Nitric acid that contains more than 30% of water is a powerful oxidizer.
The solution of this problem was overcome with finely powdered and dried PE and mixing thoroughly during the process of nitration.

[Edited on 17-12-2008 by zajcek01]
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[*] posted on 31-12-2008 at 17:24


Mhh this does not work for me, no yield is shown, the diagramm does not change whatever I type and the buttons have no use.
(Maybe its because I use Open Office)

PS: Yes I have enabled macro-use




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Free from Albert Einstein. In my opinion that fits to hobby-chemistry too.
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[*] posted on 1-1-2009 at 15:59


It does not work on OpenOffice.org :(

It only works on Micro$oft office
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[*] posted on 10-1-2009 at 10:35


Hi!
I´ve had some problems with my PE.
This is what happend:

First, I meassured up X mL of H2SO4 and Y mL of HNO3.
These were pre-chilled and later mixed, and once again chilled to a temperature about -10 C.

Then, I meassured up Z grams of Pentaerythritol.
I started the addition of PE to the nitrating-mix.

I added one gram at a time.
The PE just simply DISSOLVED in the nitrating-mix.
I added another gram. I still just dissolved.

After a while, all of the pentaerythritol were in the mix and "dissolved"
The mixture whas 100% CLEAR, which is shouldn´t bee.
There should have been a white slurry, with some crystalls in it.

The "liquid" was added to water, to precipitate the "PETN".
Nothing precipitated.

There is nothing wrong with the acids.
(96% H2SO4 and 65% HNO3, and they´ve worked just fine with other synthesis)
So, I think there is something wrong with my pentaerythritol.

Is there anyway to test it´s purity?

Have anyone of you guys had a similar problem?
If so, how did you solve it?

Could it have been any water in the PE, since it is hygroscopic?

Thanks in advance!
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[*] posted on 10-1-2009 at 15:00


Dilute HNO3, IMO, is the real problem here.
The amount of water absorbed by pentaerythritol is insignificant, considering your HNO3 contains 35%.
Distill it carefully from twice its volume of H2SO4, reconcentrate the latter to ~98% and try again.
Or better, add predried pentaerythritol to HNO3 of the highest density.
If the substrate *is* pentaerythritol, the tetranitrate will form and will precipitate on drowning.

The HNO3 should have no dissolved NO2.
If it can't be removed by blowing dry air through, treat it with a gram of urea.

[Edited on 10-1-2009 by hissingnoise]
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[*] posted on 10-1-2009 at 15:16


Quote:
Ursprugligen inlagt av hissingnoise
Dilute HNO3, IMO, is the real problem here.
The amount of water absorbed by pentaerythritol is insignificant, considering your HNO3 contains 35%.
Distill it carefully from twice its volume of H2SO4, reconcentrate the latter to ~98% and try again.
Or better, add predried pentaerythritol to HNO3 of the highest density.
If the substrate *is* pentaerythritol, the tetranitrate will form and will precipitate on drowning.


Hi!
Yes, I am aware of the fact that higher conc. the HNO3 has, the better the yield will be.
But, here´s the prob.
I have two different pentaerythritols, from two different suppliers. One of them, worked just fine, and I got an exellent yield from it. Unfortunatley, I´ve ran out from that one, and I have to use the PE from the other supplier, and his doesn´t work.
My primary question is that if there is anyway to test the PE´s purity?

Thanks for replying!
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[*] posted on 10-1-2009 at 15:27


Near anhydrous nitration is the best test I can think of, right now.
Failure under those conditions will seriously call your pentaerythritol into question.
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[*] posted on 11-1-2009 at 08:00


Maybe you could do some sort of elemental analysis by quantitatively analysing the products of the complete combustion. So, make an apparatus similar to a nitrometer, make a mix of your mystery PE and excess CuO and put it in there. Heat rapidly to ignition with some non-contaminating heat source in a stream of suitable gas (eg. nitrogen). You could pass the gas stream over an exactly known amount of a suitable dessicant to capture the water and in that way determine the amount of hydrogen in the sample.
You could then bubble the gas stream through a Ca(OH)2 slurry (with an exactly known amount of hydroxide) to absorb CO2. Then weigh the mix of CaCO3 and Ca(OH)2 to establish how much carbon was in the sample.
Using the assumption that your sample contains only carbon, hydrogen and oxygen, you then have the amount of oxygen too.

A bit labor intensive, but if you don't have access to more sophisticated equipment.....
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[*] posted on 1-7-2009 at 10:50


Quote: Originally posted by Engager  
Process with 70%HNO3 + conc. H2SO4 was repeated by another russian chemist using conc. HNO3 diluted to 70%. Same problems vere encountered, it was very surprising, because, man i'm talking about reported several completely successfull runs using this method, he also mentioned that he has no idea about what is the reason of problem. There is something terribly strange here, only difference from my case with ~15 sec away time, he was away for about 40 seconds.

[Edited on 16-12-2008 by Engager]


I'm finaly realized source of my problems with nitration of PE - it is purity of source pentaerythritol. Melting point of PE i was using in all failed nitration experiments is ~220C - that is much too low, indicating a lot of impurities are present. Oxidation problems completely disappeared then i was using pure PE from another chemical supplier. So if someone encounter severe oxidation problems, check out your pentaerythritol!

[Edited on 1-7-2009 by Engager]




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[*] posted on 2-7-2009 at 04:04


Would it not be quite easy to purify the PE from a solvent?

Btw the best yield i ever had was 89.52% of theoretical.

This was done by using 65% nitric acid.
34.0ml 65% HNO3 (analytical grade)
24.8ml 98% H2SO4 (boiled down battery acid)
10 gr PE (unknown grade)

The acids were mixed and cooled to -5 degrees.
The PE was added in three portion while keeping temp under 0.
The vessel was taken out of the ice and slowly gained temp by the exothermic reaction.
Very careful and slowly the temp was brought up to 30 degrees and maintained for 2 hours.

Then the mixture was crashed into 500ml of almost freezing water.
The next wash consisted out of 200ml 5% bicarbonate, letting it sit for a while.
The PETN was then dried on a radiator on low heat.

When almost dry, the PETN was added to 200ml of hot acetone and 1 gram of bicarbonate was added.
The mixture was then crashed on 500ml of water with chunks of ice.
And sat for a night in the freezer. (before i didn't do this and i noticed that my yield suffered, urbanski has a nice table on acetone/water/petn at different temps)

Filtered and dried in an exicator.
Yield: 89.52 %
Thats as almost 21 grams

Could be better though.



[Edited on 2-7-2009 by User]




What a fine day for chemistry this is.
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[*] posted on 10-8-2009 at 02:37


of course C4 via hexamine is easy.

PETN is relevant because it's a LOT easier to initiate. So the original posters questions about PE synthesis are totally relevant.
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[*] posted on 10-8-2009 at 09:11


Wow you guys can get FNA? Very difficult to come buy without vac dist.

Pentaerythritol has nothing to do with erythritol btw. Pentaerythritol can actually be produced by fomraldehyde and acetalhyde if I am correct. I saw it for sale from Sigma for ~$30 a kilogram. You could buy it from a middleman.

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[*] posted on 10-8-2009 at 11:59


If your KNO3 is dry and H2SO4 is ~98%, strong, fuming HNO3 will distill from it without using vacuum. . .
If you're nitrating pentaerythritol the HNO3 should be decolourised first!
Blowing dry air through it usually works; if it doesn't, just add a little urea. . .
Some things need repeating!

[Edited on 10-8-2009 by hissingnoise]
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[*] posted on 15-10-2009 at 16:00


Quote: Originally posted by User  

Very careful and slowly the temp was brought up to 30 degrees and maintained for 2 hours.
[Edited on 2-7-2009 by User]

peretherification of pentaerytrytol sulphate begin at 40 deg
use 45c and 15-20 minutes to 93-96% yeild

[Edited on 16-10-2009 by phantasy]
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[*] posted on 8-1-2010 at 18:23


The derailment of this thread on the matter of PETN that made it into the news can now be found in Whimsy, please continue there (while refraining from turning this into a political discussion).

http://www.sciencemadness.org/talk/viewthread.php?tid=13235

[Edited on 9-1-2010 by chemoleo]




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[*] posted on 30-4-2010 at 01:40
PETN synthesis


I have employed this procedure with various 50-200g PE batches and I have never had a runaway or any problems with the product.

I'll give example for nitration of 100g PE.

255mL of 96% H2SO4 is measured into a reaction vessel (I have figured out 1L flat bottomed florence flask is optimal for that purpouse since much less NOx is evolved during nitration due to small surface area and shape of flask itself). H2SO4 is equipped with thermomether (-30 to 150°C), covered with thin plastic foil and moved into a salt/ice bath until the temperature of it reaches approximately -10°C. In the mean time 390mL of 65% HNO3 are measured and moved onto a 600mL beaker which is covered with plastic foil afterwards and put into the cold water bath (~10°C). When appropriate temperature of H2SO4 is reached HNO3 is added, thermomether is fixed with the hand to the bottom and swirling is employed so the temperature of acid mixture doesn't exceed 35°C. When all the HNO3 is added mixture is moved into a ice bath and temperature is allowed to drop to 5°C. PE is then added in few 10g portions and violent swirling is used to homogenise the mixture. (I have figured out it doesn't really matter how fast you add PE, the mixture just has to be continuously stirred/swirled so no hot spots form) For instance during 200g PE nitration starting temperature of acids was 10°C and I have added all 200g of PE in mere 10 minutes, no NO2 evolved only the temperature rose to around 35°C. After all the PE has been added mixture is heated up by momentarily immersing florence flask in hot water (70-90°C), moving flask out of the water and violently swirling the mixture for some time until temperature became stable. Process was repeated for as long as the temperature of mixture was lower than 45°C. Mixture was kept at the temperature for around 30 minutes. Heating was stopped after that time and mixture was left to stand until total of 1h after beginning of addition had passed. Mixture was dumped into 5L of cold tap water and whole mixture was stirred a bit.

Crude PETN was filtered using vacuum filtration apparatus and washed few times with distilled water. As much filtrate as possible was sucked out of the crude PETN. Crude PETN was then moved in a vessel and split in half. First half was moved into a clean 1L florence flat bottomed flask and 500mL of acetone was added. Around 20g of NaHCO3 was then added onto the same flask and half of the crude PETN. In the mean time 5L of cold distilled water with small ammount of NaHCO3 dissolved was prepared and kept close. Florence flask with acetone, crude PETN and NaHCO3 was put into the water bath on electrical heater and mixture was stirred until temperature of above 60°C was reached. Majority of PETN dissolves at that temperature only NaHCO3 and salts from neutralisation are left on the bottom. Clear layer is decanted into the NaHCO3 solution which is vigorously stirred during the decantation. Process is repeated with another half of crude PETN.

My most recent attempts yielded 210g of recrystalized dry PETN.
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[*] posted on 30-4-2010 at 14:09


Nuke has a lot of experience with PETN... I recall seeing (via webcam) a kilo or two of the wonderful stuff in an ice cream tub!

Actually, Nuke, you should post the pics of the funky NG here...

Anyways... I have noted that PETN is rather sensitive to initiation by certain primaries moreso than others. For example, 50mg Pure Lead Azide was the least I could use to get reliable dets from well pressed PETN, wheras a mere 3mg or less of DPNA could be used with excellent results.

However, seeing as they are old tests, I cannot be sure of 'how' well pressed them stuff was...




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