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1-Tetradecanol

From Wikipedia, the free encyclopedia

1-Tetradecanol[1]
Skeletal formula
Space-filling model
Names
IUPAC name
Tetradecan-1-ol
Other names
Myristyl alcohol
Tetradecyl alcohol
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.003.637
KEGG
UNII
Properties
C14H30O
Molar mass 214.39 g·mol−1
Density 0.824 g/cm³
Melting point 38 °C (100 °F; 311 K)
Boiling point >260 °C
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is ☑Y☒N ?)
Infobox references

1-Tetradecanol, or commonly myristyl alcohol (from Myristica fragrans – the nutmeg plant), is a straight-chain saturated fatty alcohol, with the molecular formula C14H30O. It is a white crystalline solid that is practically insoluble in water, soluble in diethyl ether, and slightly soluble in ethanol.

1-Tetradecanol may be prepared by the hydrogenation of myristic acid (or its esters); myristic acid itself can be found in nutmeg (from where it gains its name) but is also present in palm kernel oil and coconut oil and it is from these that the majority of 1-tetradecanol is produced.[2] It may also be produced from petrochemical feedstocks via either the Ziegler process or hydroformylation.

As with other fatty alcohols, 1-tetradecanol is used as an ingredient in cosmetics such as cold creams for its emollient properties. It is also used as an intermediate in the chemical synthesis of other products such as surfactants.

YouTube Encyclopedic

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  • ✪ 361L Melting Point (#1)
  • ✪ Carrying out a melting point determination
  • ✪ AMORPHOUS AND CRYSTALLINE SOLIDS

Transcription

So, without me knowing, Josh. Hey. Is going to take one of these nine unknowns and place some of it in here, which is labeled m.p. unknown. I'm going to sit in my office while he does this. Alright, now that Josh has picked out an unknown for me to figure out what it is. I'm going to do so by doing a fast melting point, a slow melting point, and a mixed melting point. The fast melting point is just going to get me in the ballpark range. The slow melting point is what's going to be the accurate melting point. And the mixed melting point I will just use to confirm the actual identity of the unknown once I think I know what it is. The difference between the fast melting point and the slow melting point is essentially how fast the temperature ramp is increasing, how fast the degrees per Celsius are changing. A slow melting point, the more accurate one, is when the temperature increase is no more than two degrees Celsius per minute. This allows for the sample to have enough time to absorb all the heat, and this ensures the actual readout is the same temperature as what the sample is. The fast melting point, there is not enough time for the sample to absorb all the heat, so you get an erroneous high temperature reading. But again it is just for the ballpark range. And so that is the first thing I am going to do. But to get the upper limit of the melting point, we'll take a look at the possible unknowns. 4-hydroxyacetophenone is an irritant, has a melting point range of 109 to 111 degrees Celsius acetanilide is also an irritant, has a melting point range of 113 to 115 degrees Celsius benzoic acid is corrosive, has a melting point range of 121 to 123 degrees Celsius benzamide is an irritant, has a melting point range of 125 to 128 degrees Celsius malonic acid is corrosive, has a melting point range of 132 to 135 degrees Celsius salicylamide is an irritant, has a melting point range of 140 to 144 degrees Celsius salicylic acid is corrosive, has a melting point range of 158 to 161 degrees Celsius 4-hydroxyacetanilide is an irritant and has a melting point range of 169 to 171 degrees Celsius D-tartaric acid is an irritant, it has a melting point range of 172 to 174 degrees Celsius Okay, to prepare the actual sample for the instrument, I am going to take a little bit of it and put it in one of these melting capillary tubes. So if I just take the open end and try to scoop it up like this, some of it will go in there. It's at the top and if I just tap it down, it should come to the bottom there. And that's about all you really need, is about a centimeter. This is one of our newer melting point apparatuses. The on/off switch is on the side here. As soon as you turn it on, the light comes on and then it reads the temperature of the instrument and right now it's not at room temperature because it was used prior and it still hasn't cooled all the way down. But that's okay, none of our compounds melt below 69 degrees Celsius. To do the fast melting point, I am just going to set the plateau then to 175 degrees Celsius. To do that, I just hold the plateau set button and then hold the up triangle to get there. Okay now that the plateau is set to 175, if I hit start it will begin ramping and the heating light comes on, and it will get there. You see it's starting to melt. And now it's completely melted, 137 or so. Okay, I can hit the stop button. So the sample started to melt at about 127 degrees Celsius. So for my slow melting point, I'm going to want to set the temperature plateau to about 120 degrees Celsius, seven degrees lower than when I first saw it starting to melt, and then slowly increase it two degrees Celsius after it gets to 120 until I start to see my sample actually melt and that will give me the more accurate, true melting point of the sample. So again, I am going to set the plateau. This time I am going to go down to 120 degrees Celsius. Okay, then I will hit start. It will heat again. Okay now it's reached 120. It overshot it a little bit. It's already up to 122. Heating light is still on. Once it drops back down, we should see the plateau light come on. Okay, the plateau light came on and now if I hit start, it's going to start ramping and this is where it's automatically set in the instrument to have an increase of about two degrees Celsius per minute. You can see it almost starting to look like it's melting at 124 degrees Celsius. It almost looks all melted. So my sample melted at between 124 and 126 degrees Celsius. We have benzamide which has a melting point of about 126 and benzoic acid which has a melting point of about 123. These are too close for me to really tell what Josh actually put in here, so I'm going to run a mixed melting point with both of those. If this is benzamide for instance and I mix it with benzamide, then the melting point should stay the same. If however, then I mix benzoic acid with this "benzamide", then it's going to have a lower melting point and the melting point range is going to be broadened. The reason for that is because, you have to think of the terms at the molecular level where when a solid forms, it forms in such a way that it maximizes the intermolecular forces. It does so in a highly organized pattern. So any impurity that you put into that solid, it's going to disrupt that highly organized pattern. It's also going to cause the intermolecular forces to be reduced. And so the melting point itself is reduced. The melting point is broadened, has a bigger range because some of the structure starts to melt first, that's part of the structure closest to the impurities is going to melt first and part of the structure that's furthest from the impurities, where it has stronger intermolecular forces, that haven't been disrupted as much, is going to melt latter. So you have that broadening. So this is going to be able to tell me whether my compound is benzamide or benzoic acid based on whether it depresses and broadens the melting point or not. To make the mixed melting point, I'm just going to want to mix them as thoroughly as I can, in about equal ratios. I put a little black mark on this one just so I can tell the difference. Okay I have my benzoic acid and my unknown here, and I have my benzamide and my unknown in this sample here. Wow, so the one closest to me, the benzamide sample is already melting. The plateau light is on now, so I can begin ramping by hitting start and now it will increase two degrees Celsius per minute. So it's hit 124, this is where our sample began to melt last time. There might be some indication that it's doing it again, just like we'd expect. And it is. It's a little harder to tell on this one, but hopefully you can see that the sample has now melted. You can see some bubbles in there, some air pockets. So there you go. Our mixed melting point with benzamide and the sample melted at about 110 degrees Celsius, a huge depression. Our sample mixed with benzoic acid had no depression and was the same exact melting point. Conclude that this is in fact is benzoic acid. Last thing I want to show you is another melting point apparatus. This is our earlier one. You may be using one of these as well. The on/off switch is right here. And you read it just looking through here. And the temperature, instead of a digital readout, you just read it on the thermometer itself. To change the rate at which it ramps up, or the temperature, it's just this spin dial, which is zero to ten. Usually set it about five and it will ramp up pretty fast. And you can kind of get it down to about four to kind of go slow, but there all a little bit different, and so you got to work with it to find out what the right temperature settings are. So a little bit, not as nice as the other perhaps, a little bit older, but it still works just as well.

References

  1. ^ Merck Index, 12th Edition, 6418.
  2. ^ Kreutzer, Udo R. (February 1984). "Manufacture of fatty alcohols based on natural fats and oils". Journal of the American Oil Chemists' Society. 61 (2): 343–348. doi:10.1007/BF02678792.

External links

This page was last edited on 17 January 2019, at 00:18
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