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66 Acetylene

TABLE VIII Acetylenic Pesticides
Name Uses Starting material Pesticide structure
Cl
Kerb (pronamide) Control of grasses in lettuce production; other 3-Methyl-1-butyn-3-ol
crops: alfalfa, trefoil, endive, escarole CONH C(CH 3 ) 2 C CH
Cl
Barban (carbyne) Control of wild oats in production of spring 2-Butyne-1,4-diol NHCO 2 CH 2 C CCH 2 Cl
wheat, durum wheat, barley, sugar beets,
soybeans, lentils, flax
Omite (propargite) Acaricide with residual killing action; control Proporgyl alcohol OSOCH 2 C CH
of many varieties of mites; very effective (CH 3 ) 3 C O
against spider mites; used on fruit (apples,
apricots, oranges, peaches, plums) and field
crops (corn, potatoes)

extend the life of the tubing for years. These products have also effective when used with bacterial control agents for
been recommended for the acid pickling of steel to remove the control of larva-worm infestations. They are used in
mill scale. This use is smaller than oil-well acidizing. significant amounts as agricultural formulation aids.
The alkynols used in these applications are propargyl al-
cohol (1-propyn-3-ol), hexynol, ethyl octynol, and OW-1
(proprietary alkynol-based product) (see table below). VIII. PROCESSES FOR ACETYLENE
The most effective acetylenic inhibitors are secondary
acetylenic alcohols of C 6 –C 8 chain length, with the hy- PRODUCTION
droxyl group α to the terminal ethynyl group. Propargyl
Common raw material sources for the production of acety-
alcohol, a primary alkynol, is somewhat less effective than
lene are coal, natural gas, and liquid petroleum feedstocks
the best inhibitors, but since it is a by-product of the Reppe
such as naphthas and light oils. Calcium carbide tech-
process it is significantly less expensive than hexynol or
nology using coal (coke) and limestone was the earliest
ethyl octynol. The total 1984–1985 usage of acetylenic
means of producing acetylene. It is still used, but on a
corrosion inhibitors was estimated to be about 3–4 mil-
limited scale.
lion pounds with propargyl alcohol accounting for about
Petrochemical acetylene, based on natural gas and liq-
half of this total.
uid feedstocks, began to emerge as a competitor of the car-
bide process in 1940–1950. Until the mid-1960s acetylene
wasstillthefavoredrawmaterialforsuchproductsasacry-
E. Acetylenic Pesticides and Adjuvants
lates, vinyl chloride, vinyl acetate, chloroprene, acryloni-
Acetylenic compounds have found selective uses as her- trile, and chlorinated hydrocarbons. However, as steam
bicides and miticides in the control of weeds and pests. cracking of C 1 –C 3 alkane feedstocks to olefins (ethylene,
It is likely that if more research and development effort propylene) became important, the role of both petrochem-
were extended to triple-bonded compounds, superior pes- ical and carbide acetylene declined markedly by the mid-
ticides would be developed. Three acetylenic compounds 1970s. These olefin cracking processes also produced by-
used commercially are Kerb (pronamide), Barban (car- product acetylene, which could be recovered by selective
byne), and Omite (propargite). They are summarized in solvent extraction and sold or utilized for chemical pro-
Table VIII and Sections XII.A–XII.C in terms of the cesses by nearby chemical companies. Companies such
acetylenic starting material, pesticide structure, and uses. as Union Carbide, Tenneco, and Monochem have such
It is believed that the use of Omite is considerably by-product acetylene facilities in Texas and Louisiana.
greater than that of either Kerb or Barban. Surfynol Table IX summarizes processes that were or are prac-
104 (tetramethyldecynediol) and the Surfynol 400 series ticed in the United States and elsewhere, with the excep-
(ethoxylated S-104), while not pesticides, have been ex- tion of the newer AVCO coal-based plasma are process.
tensively evaluated as adjuvants for use with crop herbi- Coal-based processes such as calcium carbide or AVCO
cides such as atrazine, alachlor, basagran, sencor, treflan, will probably become important after the year 2000 as oil
and kerb. In most cases they have been found superior to reserves become depleted.
standard commercial surfactants of the nonionic and an- Petrochemical acetylene processes are characterized
ionic types, if used with the above herbicides. They are by a common principle. A hydrocarbon feedstock is