[Enthalpy]

Hello everybody!

I had in mind that addition of R-X to alkenes (and alkynes) R'=R" to obtain RR'R"X was a common and usual reaction, but now I don't find any description on the Web - only X₂ and HX additions.

So: did I hallucinate that?

[Enthalpy]

I did. But what does exist is the
Kharasch addition, or Atra (atom transfer radical addition)
with more halogen atoms and an olefin. Where possible, it seems efficient.

It seems little flexible, with the compounds being almost always
CXCl₃ where X is Cl, Br, H
and CH₂=CH-CH₂-R
and the product follows anti-Markovnikov
CCl₃-CH₂-CHX-CH₂-R

The reaction starts with a peroxide, and the propagation steps for CCl₄ are
C°Cl₃ + CH₂=CH-CH₂-R  Cl₃C-CH₂-C°H-CH₂-R
CCl₄ + CCl₃-CH₂-C°H-CH₂-R  C°Cl₃ + CCl₃-CH₂-CHCl-CH₂-R

This must be the original paper:
http://science.sciencemag.org/content/102/2640/128.1

A little bit more on page 737 of
Mono-Olefins: Chemistry and Technology
By F. Asinger

Not detailed
https://en.wikipedia.org/wiki/Kharasch_addition

Few variants exist. Br can widely replace Cl, organic acids maybe.
https://www.princeton.edu/chemistry/macmillan/group-meetings/NJ_ATRA.pdf
most development is made on catalysts.

This group achieved the addition with CH₂Cl₂
https://www.jstage.jst.go.jp/article/cl1972/7/4/7_4_367/_pdf
with catalysts and a fair yield.

Articles tell "UV doesn't work" but at that time, UV meant Hg lamps that affected CCl₄ little. It could be worth a try with KrCl lamps now, or where the alkene permits it, Xe₂ lamps.
http://www.chemicalforums.com/index.php?topic=77307.msg283221#msg283221
diagram "Geminal haloatoms".

Xe₂         KrCl        lp-Hg
172nm       222nm       254nm
--------------------------------
7*10^-18    1.5*10^-19      1*10^-21    CCl₄
4*10^-18      1*10^-20      3*10^-23    CHCl₃
6*10^-18      4*10^-19      5*10^-19    CBrCl₃
--------------------------------
cm²          cm²         cm²

[Dan]

Carbohalogenation of alkenes and alkynes under Pd-catalysis is known - as far as I know only intramolecular reactions though. Check out Mark Lautens' group.