halogens

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Some freshly prepared, perfectly pure, crystalline 1,1,1,3,3,3-hexafluoroisopropyl-tosylate. 

An interesting info about partially fluorinated reagents: ethyl-tosylate is a quite toxic compound what can alkylate your DNA and could easily cause cancer, since it’s a quite good alkylating reagent. If 2,2,2-trifluoroethyl-tosylate is used instead of ethyl-tosylate in a reaction (+3 fluorine atoms at the end of the chain) the reactivity of this reagent decreases 1000 times. The interesting part comes here: the above prepared 1,1,1,3,3,3-hexafluoroisopropyl-tosylate is not reactive under standard reaction conditions, therefore I can’t use it as an alkylating reagent.

Halogens

Trends

  • reactivity, electronegativity, mpt, bpt, all increase up the group  because the ionic radius is smaller up the group, as there is less shielding, so the attraction between the electrons and nucleus will be stronger towards the top
  • the solubility increases up the group because they are more electronegative and polar, so can overcome the forces of the hydrogen bonds in water. note that fluorine also exhibits hydrogen bonding.
  • they look darker and become more volatile down the group, this is because there will be more electrons in the elements towards the bottom, so they will have stronger intermolecular forces. this is why iodine is a solid, bromine, a liquid, and chlorine and fluorine are gases.
  • become stronger reducing agents as you go down

Reactions

  • with hydrogen H2 + X2 —> 2HX
    chlorine needs dark
    bromine needs a platinum catalyst at high temperature
    iodine needs a platinum catalyst at a high temperature 
  • hydrogen halide + ammonia gas —> ammonia halide
  • halogen + sulphuric acid —-> hydrogen halide (they are oxidised)
    chlorine= steamy fumes (HCl)
    bromine= misty fumes and red/ brown vapour (HBr)
    iodine= violet fumes (HI)
  • potassium halide + Cl2 —> potassium chloride + halogen
  • disproportionation reactions with alkali

Tests 

add dilute nitric acid and aqueous silver ammonia.

  • chlorides= white ppt
  •  bromides = cream ppt
  • ioides = pale yellow ppt

to that ppt, add dilute, then concentrated ammonia

  • AgCl= dissolves in dilute ammonia
  • AgBr= only dissolves in concentrated ammonia
  • AgI = does not dissolve in any
snippet one: fluorine

fluorine explodes into the room, yelling about some nonsense or another. i make a spirited attempt to ignore her. she is too damn perky and it is too damn early. i turn another page of my book, hoping she would see reason and leave me the hell alone. no such luck.

‘did you even listen to anything i just said?! stop reading that dumb book, you can read that dumb book any time, but what you can’t do is listen to me any time, because i’m only going to say this once more and then i’ll never say it again. never ever ever again.’

i thumb another page and scan the words with passionate and focused intent. she flicks her short blonde hair and fixes her piercing, searching eyes on me.

'astatine, you cold and heartless cow, can you not just humour me for a mere six seconds? if it weren’t for all our other sisters, i’d be your only sister and if i died, you’d live on never knowing what i, your only sister, would have said…’ she lets out an almost-convincing sigh. i admit defeat.

'… you have six seconds’

she takes a deep breath and i brace for impact.

'i need money’

Another snapshot from fluorous chemistry. Under the organic layer that small yellow oily layer is a highly fluorous.

Fluorous chemistry involves the use of perfluorinated compounds or perfluorinated substituents to facilitate recovery of a catalyst or reaction product. Perfluorinated groups impart unique physical properties including high solubility in perfluorinated solvents. 

A perfluorinated compound (PFC) is an organofluorine compound containing only carbon-fluorine bonds (no C-H bonds) and C-C bonds but also other heteroatoms. PFCs have properties that represent a blend of fluorocarbons (containing only C-F and C-C bonds) and the parent functionalized organic species. For example, perfluorooctanoic acid functions as a carboxylic acid but with strongly altered surfactant and hydrophobic characteristics.

For more:  István T. Horváth (Ed.) Topics in Current Chemistry 2011: “Fluorous Chemistry”  http://link.springer.com/chapter/10.1007%2F128_2011_282

youtube

my friend uploaded this YEARS AGO and i just rewatched it today, BUT IT’S AMAZING!!!!!!

omg I’m bromine, the broest element of them all. we’re really funny. enjoy

astatine can suck it

Did you know that some #acne, particularly around the mouth or on the chin or jawline, is caused by #halogens? Traditional anti-acne treatments might help but to clear it — simply yet dramatically — you need changes like in your toothpaste, certain vitamins, medication and salty foods? Check out this great “Anti-Acne Halogen-Free Diet” now on skintelligencenter.com!

I have the weirdest science teacher ever. I kid you not, he was talking about the periodic table, and he called the halogens (group 17) or whatever horny because they’ll ‘mix with anyone.’ Then he called another group bisexual. Then we were talking about chemical equations and the different kinds, and he kept saying that one element 'hooked up with another at prom’ and 'went home to have some more fun’… like are teachers even allowed to do that? lol