Synthesis And Biological Activity Of Nitrogen-and Oxygen-Containing Derivatives From 3-Carene

The extensive use of chemical products has seriously affected the ecology and the health of humans and animals.The development of green and efficient pesticides has become a consensus among mankind.Plant-derived pesticides have received extensive attention due to their wide sources,diverse activities,and environmental friendliness.As a monoterpene from turpentine,3-carene is rich in natural yield,and it also has a wide variety of derivatives with multiple functions due to its excellent reactivity,which is widely used in spices,pesticides,medicine,and other fields.In this paper,based on the in-depth study of the structural transformation mechanism of 3-carene,51 nitrogen-and oxygen-containing derivatives of it in 3 categories were synthesized.Then the studies on their activities were made,which confirmed that they have good utilization value in the field of pesticides.The research results not only enriched the types of botanical pesticides,but also expanded the field of turpentine utilization.The details are as follows:1.A process route for the synthesis of carbamate from 3-carene was established.First,Cr O₃/Al₂O₃was prepared by impregnation method.Under its catalysis,3-carene reacted with oxygen at room temperature to generate carenones（2～4）.The using of new catalyst improved the product selectivity and eliminated the chromium residue;Using 13X Molecular sieves as catalyst,2～4 were isomerized to carvacrol（10）and 5-isopropyl-3-cresol（11）with a conversion rate close to 100%and a selectivity of more than 98%.This process is very efficient with short reaction time and high efficiency.It broke through the technical bottleneck that the traditional ones were difficult to efficiently prepare 11;14 carbamates were prepared from 10 and 11.The activity tests proved that 4 isopropyl cresols and 6 carbamates displayed excellent herbicidal activity,and 3 carbamates also showed good insecticidal activity.The structure-activity relationship showed that in isopropyl cresols,the activity of 11 itself and its derivatives was generally higher than that of other isomers;the activity of N-methyl carbamate was significantly higher than that of other structural types.2.Using the special structure of 3-carene,the key technology for the transformation from 3-carene to 1,8-cineole was established.First,OH and Br were introduced on the double bond of 3-carene,and then acid was added to promote the cleavage of its three-membered ring to form a carbocation.Then a cineole structure formed through intramolecular nucleophilic substitution by OH,and Br was used as the active site for subsequent reactions.The 1,8-cineole derivatives whose C_-2 positions were substituted by Br,OH and NH₂ were prepared,and the corresponding isomers with carane structure were synthesized.Among them,4 compounds have significant herbicidal activity,and the structure-activity relationship shows that the addition effect of Br is the strongest,followed by OH,and finally NH₂,and the skeleton structure of the compounds has no obvious effect.3.The synthetic route of diamide compounds from 3-carene was established.3-Carene undergoes Ritter reaction first and then undergoes alkaline hydrolysis to generate 1,8-p-mentanediamine（48）,then several diamide compounds were synthesized by the reaction of 48 with acid chloride.A new hydrolysis process is established by carrying out the reaction in a sealed reactor with low-boiling solvent,and the reaction system reached the target temperature by spontaneous pressure increase,which both improves the reaction efficiency and simplifies the separation of products.Comparing to the process that occurred under atmospheric pressure with high-boiling solvent,the reaction rate was doubled and the time required to achieve the same product yield was reduced from 18 h to 9 h,and the product selectivity was increased from 75%to more than 95%,the total product purification time was reduced from 33 h to 4 h,and the product yield was increased from 29.9%to 85.6%.Activity tests show that 48 has the potential to be developed as a botanical herbicide.4.The role and change of 3-carene ring structure in its derivatization reaction were deeply studied,the reaction mechanisms of 3-carene under different reaction atmospheres were described,and the structure transformation rules of 3-carene were summarized:Acidic environment is easy to make the three-membered ring in the structure undergo a ring-opening reaction to generate six-membered ring compounds;High temperature and metal catalysis can promote the ring expansion reaction of the three-membered ring to generate seven-membered ring compounds;Low temperature or basic or neutral processes are beneficial to the retention of three-membered ring structure and generate bicyclic products.