Right. So the problem with doing it with normal alcohols is that alcohols are not acidic enough to protonate the CH2 on diazomethane. The solution is to use a protic acid like HBF4 as you mentioned. This gives CH3-N2(+) which is an excellent alkylating agent.

OK

Under normal conditions, no reaction, but if the CH2N2 is agitated photochemically there could be formation of carbene and C-H insertion to either C-1 or C-2 of propane. Not something I would recommend.

Great comment. Thank you. Were you converting carboxylic acids to esters? Are carboxylic acids present in a large majority of herbicides?

I perform 200 to 300 herbicide analyses per year through MTH 8150 SW 846. 3 version and I extracted my own samples.

I was well trained and well-versed in the safety hazards to being very cautious, and handling during the organic synthesis.

No ground glass joints!!. Ice down bath in the receiving flask. The reactions took place under a fume Hood and behind safety tempered blast shield.

Everything was smooth glass joints, triple rinse with petroleum ether production of least 100 to 200 milliliters of diazomethane at the end the synthesis was placed put into 4 or 5 40 mil Amber – Brown Teflon sealed capped then stored at 4 degrees Celsius in the laboratory refrigerator. Until was needed for reagent during the second part of the extraction process of MTH 8150.

After the rigorous extraction of at least 10 to 15 samples per day which took two days. Or 2/8 hour shift work., after the extraction of samples with diethyl ether was almost complete post Nordstrom blowdown throughs volume Zymark turbovap nitrogen blowdown. I would use the diazomethane 1 mil into each vial let it react for at least 2 to 3 minutes until bubbling stopped or I add silicic acid to stop the reaction. Transferred to GC vial be via pipette, capped, transferred to the GC /MS . For years, I never gave any thought about being injured on the job.

Yes, in the presence of strong acid, CH2N2 is protonated to CH3-N2(+) which is a superb alkylating agent. This will react with alcohols to give methyl ethers.

I’m not aware of the Kohler synthesis. What you’re describing is similar to the Buchner reaction: https://en.wikipedia.org/wiki/B%C3%BCchner%E2%80%93Curtius%E2%80%93Schlotterbeck_reaction