In what context is that information presented? Can we have a link
Perhaps what the picture is describing the decompisition products created when you heat borneol or terpinen-4-ol to 401f?
Benzene is being produced in this instance?
Does anyone one what this means? Terpinen-4-ol?
Is it the terpene terpinolene?
This is an important issue and it would. E stellar if the OP gave us some less vague info. I looked at borneol and it is not listed as decomposing before boiling; what’s neat is that it almost sublimates :).
Terpineol (which is not the same as terpinolene) however does decompose:
“When heated to decomp it emits acrid smoke and irritating fumes.
Lewis, R.J. Sr. (ed) Sax’s Dangerous Properties of Industrial Materials. 11th Edition. Wiley-Interscience, Wiley & Sons, Inc. Hoboken, NJ. 2004., p. 3363”
But maybe it’s slmething else too!
Terpene alcohols can be sep’d from terpenes by the Fischer estererification using boric acid; anyone who want to market a flavor without the terpineol can HMU 
I knew terpene alcohols could be prepared via the fischer esterification process from their corresponding terpenes. Im very curious on this subject, can I kindly ask what do you mean by sep’d?
Sorry, separated
See:
Method for the separation of terpene alcohols from pine oil
United States Patent 2050671
However there are more modern methods of ester formation which are substantially neutral and not acidic and in some preps of cannabis it may be advantageous to consider a more modern path. For example if there was something else in the reaction sensitive to acids, and it was not possible to fractionate it via distillation, one may choose the Steglich process.
Thats what i thought you said, in this process how are they being separated from rhe rest of the terpenes?
Dont the terpwne alcohols still have a similar boiling point to their parent molecules?
They do, the are often a tad heavier than the monoterpenes but lighter than the sesquiterpenes, so to isolate them via distillation would take doing it very well, which is never easy.
Most of the monoterpenes boil a bit below 200C, most of the terpene alcohols just around 200, and the sedquiterpenes much higher. I think it’s not impossible that one could fractionally distil the terpene alcohols out, terpinolene is one of the higher boiling hydrocarbons as it boils at 185 allegedly, but that’s below linalool enough (197) that despite their potential to boil together it should be doable.
Certainly not impossible but is it economical?
I want to try to esterify some terp sauce instead of distilling it from thensolution just see what the flavor/smell ends up like.
It qould cause all types of isomerization but i wouldnt mind.
Yes! Fractional distillation takes more knowledge and careful attention but it’s not more expensive inherently to run.
Now, I don’t know if it can compete cost wise to “terpenes” but we all know how lacking the non-cannabis formulations are, compared to dope terps
Buchi teaches the use a vacuum controller, and changing the pressure while maintaining a water bath (with ping pong balls to prevent evaporation) at 60C. It’s a lot less messy to fractionate by vacuum control than heat and you can find used vacuum controllers rather cheaply
Less messy in terms of what as it relates to extracts being distilled? A vacuum control introduces a small leak to maintain a set point that is stable and known but has the drawback that in order to do this pressure must be allowed to rise somewhat. The vacuum in my rigs must run at full ultimate vacuum to achieve the boiling temperatures not otherwise possible for heat sensitive organic compounds (except through steam distillation). Fractionation is a combined effect and generally speaking is directly related to the enthalpy of a closed system. The lower the enthalpy then the more defined fractionation will be IF the energy is high enough of course to effect the needed phase changes.
With respect I disagree with the conclusion that a vacuum controller in the form of a leak back bypass device assists fractionation in this case whereas precise control of the heat input into the system absolutely will. 
Looking at the link in the image, Why Cannabis Vaporization?, and following to another link, I think this may be the source: NORML / MAPS Study Shows Vaporizers Reduce Toxins in Marijuana Smoke, which is from ca. 2004.
Looks like the image was custom made by someone who complied claims from at least the link above. If you follow the two above links and their links, you’ll be lead to a few studies from 2001 to 2016 which may also have been used to create the image.
At least that’s my guess! 
Ive seen this before, and it wasnt just a screen shot cut by someone trying to raise concern.
Posting full page informatiin is important as it doesnt leave the community playing a guessing gameTrying to track the scource info… Will post if found. @Toncbn3 please share link if its a public post.
You may know that hydrodistilation can separate the cannabinoids from the volatile spirits, so isomerisation of the terpenes and alcohols would be the issue to avoid. That being said, it’s is possible that some of the degradations can be eliminated with proper planning and technique.
Sparging the liquid to be distilled well, which means first subjecting it to a hard vacuum while warm, and then bubbling in an inert gas, and repeating this process several times, would stop a major source of oxidation.
Next, proper vacuum technique will have to be perfect. I bet 99% of people here are leaking air into their vacuum rigs. I don’t have time to go into the depth of all the ways you can mess this up, but the is literature if you look. You can pull a HARD vacuum with some good equipment and technique.
Edit
As long as your technique works, yay! I love my vacuum regulators :). I am absolutely speaking generally about vacuum distillation, and just then about isolation of terpene alcohols.
How hard a vacuum do you pull?
Edit 1:
At one torr thc boils at 44C according to skunk farm, which is way below the 60C I mentioned. That’s hardly a hard vacuum.
Edit 2:
http://www.repairfaq.org/sam/lasercva.htm
This is a great general reference - way more than we need as organic chemists ha ha but it’s a great aid.