Fats and Oils in Agriculture W.W. ABRAMITIS, Agricultural Chemicals Research and Development, Armak Company, McCook, I L 60525 ABSTRACT AND SUMMARY Fats, oils, a n d t h e i r derivatives are reviewed, in t h e i r roles as emulsifiers a n d s u r f a c t a n t s a n d as pesticide derivatives, a n d in t h e i r a c t i v i t y per se. As emulsifiers a n d s u r f a c t a n t s t h e y o f f e r a wide range o f h y d r o p h i l e - l i p o p h i l e b a l a n c e ( H L B ) values t o assist f o r m u l a t o r s in d e v e l o p i n g saleable p r o d u c t s . T h e i r lipoid solubilities aid in e v a p o r a t i o n r e t a r d a t i o n , p l a n t p e n e t r a t i o n , a n d a b s o r p t i o n . O f t e n t h e y greatly i m p r o v e t h e p e r f o r m a n c e o f t h e active ingredients. N i t r o g e n derivatives s u c h as a m i n e s a n d q u a t e r n a r i e s , f a t t y alcohols, acid esters, a n d o t h e r a g r i c u l t u r a l chemicals are reviewed. E x a m p l e s are cited o n t h e e f f e c t of t h e l e n g t h o f t h e c a r b o n c h a i n a n d t h e i r n u m b e r in s u c h h e r b i c i d e s as 2,4-D a n d d a l a p o n , as well as t h e biological p r o p e r t i e s of various a l i p h a t i c groups in i n s e c t larvicides, p l a n t g r o w t h regulators, a n d fungicides. T h e role vegetable oils can play in t h e l o o m i n g e n e r g y s h o r t a g e s as p e t r o l e u m oil s u b s t i t u t e s is discussed. T h e y offer a challenging f u t u r e in agric u l t u r a l applications.
INTRODUCTION Fats a n d oils are valuable sources o f r e n e w a b l e , versatile, b i o d e g r a d a b l e derivatives t h a t have a n i m p o r t a n t i m p a c t o n agriculture. T h e y are used as emulsifiers f o r oil-in-water a n d water-in-oil s y s t e m s , as s u r f a c t a n t s a n d w e t t i n g agents, as pesticide i n t e r m e d i a t e s , a n d as a g r i c u l t u r a l aids p e r se.
EMIl LSI FI E RS AND SIlR FACTANTS T h e wide range o f emulsifiers a n d s u r f a c t a n t s can be classified as a n i o n i c , cationic, n o n i o n i c , a n d a m p h o l y t i c (1) ( T a b l e I). W i t h i n these g r o u p s o n l y a p o r t i o n have b e e n cleared b y t h e E n v i r o n m e n t a l P r o t e c t i o n A g e n c y for use in pesticidal applications. Most o f t e n b l e n d s of a n i o n i c s a n d n o n i o n i c s , a n d c a t i o n i c s a n d n o n i o n i c s , or b l e n d s w i t h i n t h e same g r o u p are used to best f o r m u l a t e a p r o d u c t or c o m b i n a t i o n o f p r o d u c t s . O f p a r t i c u l a r i m p o r t a n c e is t h e h y d r o philic-lipophilic balance, r e f e r r e d to as HLB value, o f t h e emulsifier or s u r f a c t a n t s t r u c t u r e . As a n e x a m p l e , a n o n i o n i c series o f emulsifiers s u c h as t h e e t h y l e n e glycol esters range f r o m a n HLB value o f 1 . 5 - a l m o s t t o t a l l y fat soluble, to a n HLB value of 1 9 a l m o s t t o t a l l y w a t e r soluble (Fig. 1). In general, c o m p o u n d s in t h e HLB r a n g e o f 1 t o 4 are o n l y fat soluble. I n t h e 4 t o 7 range, t h e emulsifers are used to b r i n g w a t e r - s o l u b l e p r o d u c t s i n t o a n oil to f o r m i n v e r t e m u l s i o n s ( m a y o n n a i s e - t y p e ) . In t h e 7 t o 9 range, t o x i c a n t s are generally dispersed in water. T h e 8 to 20 range covers oil-in-water e m u l s i o n s a n d in some cases, t r u e solutions. Up u n t i l t h e early 60s, t h e active pesticide i n g r e d i e n t s s u c h as c h l o r d a n e , DDT, t o x a p h e n e , b e n z e n e h e x a c h l o r i d e , a n d t h e p h e n o x y h e r b i c i d e s were relatively i n e x p e n s i v e . F o r m u l a t o r s r e l u c t a n t to increase t h e cost o f t h e p r o d u c t found the anionics cheap and compatible with nonionics a n d t h e active i n g r e d i e n t ; t h e y b e c a m e t h e emulsifiers o f choice. However, a n u m b e r o f t h e c h e a p t o x i c a n t s h a v e b e c o m e i m p l i c a t e d as b e i n g t o o p e r s i s t e n t a n d are b e i n g b a n n e d as e n v i r o n m e n t a l p o l l u t a n t s : T h e y are b e i n g r e p l a c e d w i t h less p e r s i s t e n t b u t m o r e e x p e n s i v e pesticides. T h e t r e n d t o d a y is to seek m o r e efficient emulsifiers t h a t will e n h a n c e t h e a c t i v i t y o f t h e t o x i c a n t a n d t h u s l o w e r t h e J. AM. OIL CHEMISTS' SOC., November 1977 (VOL. S4)
t r e a t m e n t costs p e r acre. T h e c a t i o n i c s o n c e t h o u g h t t o b e t o o e x p e n s i v e are n o w p l a y i n g a n i n c r e a s i n g role in i m p r o v ing f o r m u l a t i o n s . F o r e x a m p l e , M a t t e s o n a n d T a f t (2) s c r e e n e d 87 a d j u v a n t s f o r t h e i r i n f l u e n c e o n t h e s y s t e m i c activity of phorate {0,0-diethyl-S-[(ethylthio)-methyl] phosphorodithioate} and 4-dimethylamino-3,5-xylyl-Nmethylcarbarnate (Zectran| added to nutrient solution in w h i c h c o t t o n seedlings were growing. Boll weevils were c o n f i n e d for 4 8 h r o n the plants. O n l y t h r e e a d j u v a n t s , all q u a t e r n a r y a m m o n i u m chlorides, e n h a n c e d t h e activity o f Z e c t r a n f r o m an average of 2 0 . 4 % m o r t a l i t y t o as high as 76.8%. A n i o n i c s can a f f e c t a b s o r p t i o n also. S a n d s a n d B a c h e l a r d (3) s h o w e d t h e e f f e c t of six s u r f a c t a n t s a n d o n e solubilizer o n t h e u p t a k e of p i c l o r a m b y Eucalyptus viminalis a n d E. polyanthemos leaf discs. T w o s u r f a c t a n t s - l a u r y l t r i m e t h y l TABLE I Classification of Emulsifiers and Surfactants a I.
ANIONIC bA. Carboxylic acids 1. Carboxyl joined directly to hydrophobic group. 2. Carboxyl joined through an intermediate linkage. bB. Sulfuric esters (sulfates) 1. Sulfate joined directly to hydrophobic group. 2, Sulfate group joined through intermediate linkage. C. Alkane sulfonic acids 1. Sulfonic group directly linked to hydrophobic group. 2. Sulfonie group joined through intermediate linkage. D. Alkyl aromatic sutfonic acids 1. Hydrophobic group joined directly to sulfonated a r o m a t i c nucleus.
2.
Hydrophobic group joined to sulfonated aromatic nucleus through intermediate linkage. E. Miscellaneous anionic hydrophilic groups 1. Phosphates and phosphoric acids. b2. Persulfates, thiosulfates, etc. b 3. Sulfonamides. b4. Sulfamic acids, etc. 1I. CATIONIC A. Amine salts (primary, secondary, and tertiary) 1. Amino group joined directly to hydropbobic group. 2. Amino group joined through intermedaite linkage. B. Quaternary ammonium compounds 1. Nitrogen joined directly to hydrophilic group. 2. Nitrogen joined through an intermediate group. C. Other nitrogenous bases 1. Nonquaternary bases (e.g., guanidine, thiouronium salts, etc.) 2. Quaternary bases. D. Nonnitrogenous bases 1. Phosphonium compounds. 2. Sulfonium compounds, etc. 1II. NONIONIC A. Ester linkage to solubilizing groups B. Ester linkage C. Amide linkage D. Miscellaneous linkages E. Multiple linkages IV. AMPHOLYTIC A. Amino and carboxy 1. Nonquaternary 2. Quaternary B. Amino and sulfuric ester 1. Nonquaternary 2. Quaternary C. Amino and aikane sulfonic acid bD. Amino and aromatic sulfonic acid E. Miscellaneous combinations of basic and acidic groups aSee reference (1). bNonfat or vegetable oil origin. 853A
HL8 VALUES
19 18 17 16
/~./
/ -;o/~"
15 14
O/W
13
.
12
OT
11
/
l0
9
8 fp
LEGEND
? 6
LEGEND
5 4
/
3
~
9 S
"*Soy"amine acetate
(~T
"Tallow"amine
9
" T a l l o w " amine acetate salt
O
N, N-Dimethyl-2-(
LDs0 well
r 1000 ,
Primary amine acetate salt
11~ Monostearate e=ter Distearate e~ter
0
Primary amine
9
( ~ S "Soy"amine
9 Motrolauraraesler i-1 Oilaurate ester 9 Monooleate ester O Dio~eate ester
~1~
/s !
O
C1
,
~alt
above this value
1 -hydroxyetbyl) alkylammonium chloride (tertiary amine)
|
I
I
I
I
|
C8
ClO
C12
C14
C16
C18
CHAIN LENGTH
POLYETHYLENE GLYCOL UNITS
FIG. 1. Effect of addition of polyethyleneglycol (PEG) units on hydrophile-lipophile balance (HLB) value. YELLOW NUTSEDGE
AFTER 26 DAYS
% Kill 100 90 80
/9 ~ /
7Q' 60' 50'
e/e
Q
[]
40' 30' LEGEND 20'
9
10'
1"1 D i m e . tertiary a m i n e
Primary a m i n e
6 Ibs A c t A c i d / A c r e
0 No
7
8
9
10
11
12
,
,
,
,
,
,
C
14
15
16
T
18
DIS
FIG. 3. Effect of varying chain lengths of aliphatic amines and their salts on the larvicidal activity of the compound. ammonium chloride (Arquad | 12/50) and cocodimethylbenzylammonium chloride (Kemmat | QC-23)-were cationic; t w o - c a l c i u m dodecyl benzene sulfonate (Kemmat SC-15) and triethanolamine dodecyl benzene sulfonate (Decol | T / 7 0 ) - w e r e anionic; and t w o - n o n y l p h e n o l condensate with 9 moles ethylene oxide per mole of phenol (Kemonic | 909) and monosorbitan lauryl ester with 20 moles of ethylene oxide (Tween | 2 0 ) - w e r e nonionic. The solubilizer used was dimethyl sulfoxide (DMSO). The two anionics produced the greatest uptake o f picloram by the leaf discs, closely followed by the quaternary, trimethyldodecylammonium chloride. Other examples of surfactant enhancement can be readily found in the literature. Surfactants such as the long-chain fatty amine salts of fatty acids can form invert emulsions. These emulsions are unique in that the active pesticide can be in either the water or oil phase or both. This system is advantageous in preventing drift and reducing volatility.
JOHNSON GRASSSEEDLING PESTICIDE DERIVATIVES
100 T
90
S
80 70 60 50 40
/ e
c
30 20 10
4 Ibs A c t . A c i d / A c r e
0
,
No.
7
8
9
,
,
,
10
11
12
C
,
,
,
,
i
,
14
15
16
Z
1B
O,S
FIG. 2. Activity of dalapon amine salts after 26 days (greenhouse trials). 854A
The most important fatty derivatives in agricultural applications are those containing nitrogen. They fall in the categories of primary, secondary, tertiary and poly-amines; quaternary ammonium compounds; imidazolines; thioureas; and guanidines. Several studies were made by Jansen (4) (USDA) that illustrate the importance of chain length, the number of long chain alkyl groups, the effect of ethoxylation, the solvent and even the dilution rate of application when the surfactant is attached to a herbicide such as 2,4-D. He used soybeans as an indicator plant and a sublethal dosage (0.1 lb/A) to illustrate the biological effects. In aqueous sprays, the C 8 and C12 saturated primary amines were active but the C16 and C18 were inactive. In soy, oleoyl, and hydrogenated-tallow amines, only the H-ta110w was inactive; the activity of soy and oleyl amines J. AM. OIL CHEMISTS' SOt., November 1977 (VOL. 54)
\
10-10--
r >
9
9 100-1130 LEGEND
O Secondaryamine LEGEND
9
(~ Trimethyl.2-(1-hydroxyethyl)alkylamrnoniumchloride 9 Benzyld~methyt-2.(1,hydroxyelhyt)alkylammoniumchtorido
O T e r t i a r y amine ( ~ Tertia~f amine acetate salt
O Benzyldirr~thyl-2-(1-hydroxyalkyl)alkylammo~iumchlorid~ 1000 - -
S~ondary amine acetate salt
LDso v a l u e s
above
20 rag/64 sq.cm, area
LDs0 values above 20 rag/64 sq, cm, area I
1
c8
c10
I
1
I
c12
C14
c16
c18
I
I
I
I
0
1
2
3
NUMBER OF C12 GROUPS
CHAIN LENGTH
FIG. 4. Effect on biological activity with increasing length of the aliphatic group in quaternary ammonium compounds. was attributed to the presence of unsaturation. In secondary and tertiary amines, the presence of two high molecular weight hydrocarbon substituents showed practically no activity; but with two low molecular weight moieties and one long aliphatic substituent, the compound was very active in an aqueous system. E t h o x y l a t i o n of either the long chain monoalkyl primary or long chain dialkyl secondary amines proved to be one of the most influential factors determining their a c t i v i t y in water. Progressive ethoxylation increased activity, most markedly in the case of the secondary amine. Jansen concluded that the structural features associated with the activity of surfactant-amine salts of 2,4-D in water are those commonly associated with the hydrophilic characteristics of the surfactants, the decreasing order of importance being the degree of ethoxylation and high degree of unsaturation in the aliphatic amine and the saturated hydrocarbon chains with fewer than 16 carbons per amine. The reverse is true, to a large extent, of the lipophilic surfactant characteristics in an oil medium. In original studies not previously reported, we have investigated the effect of chain length of amine salts of dalapon (2,2-dichloropropionic acid) applied to yellow nutsedge and Johnsongrass seedlings in the greenhouse (Fig. 2). The results showed trends similar to those found by Jansen except in the case of yellow nutsedge, where the tertiary amine salts peaked at Cts. But against Johnsongrass, all derivatives showed high activity. Tertiary amine salts of endothall acid (5) show unusually diverse biological activity. Dimethyl "coco" amine endothall is applied as an aquatic herbicide to control algae and noxious water weeds. The same compound in combination with tributylphosphorotrithioite (Folex| a defoliant, very effectively accelerated desiccation and defoliation of cotton J. AM. OIL CHEMISTS' SOC., November 1977 (VOL. 54)
FIG. 5. Effect of increasing the number of higher aliphatic groups on the activity of amines and their salts. to improve harvest. The amine salt is also marketed as an effective harvest aid for alfalfa and clover seed, and as a potato vine killer. It has been tested in Hawaii and found to be an effective sugar cane ripener (6). INSECTICIDAL ACTIVITY The effect on insecticidal activity of chain length and number of aliphatic groups in free amines, their acetate salts, and quaternaries was also studied by the author with housefly larvae as the test species (Fig. 3). The insecticidal activity of the free amines and their salts peaked at Ct2 alkyl with some increase in activity due to unsaturation. In the case of alkyl trimethylammonium chlorides, the peak activity was at Ct6 and for the benzyl quaternary the peak was at C12 alkyl (Fig. 4). Increasing the number of alkyl groups from one to two or three greatly reduced the biological activity of secondary and tertiary amines; but for the case of alkylmethylammonium compounds, two long chain groups were most active (Fig.s 5 and 6) (7). Similar studies on the effect of varying chain lengths and the number of aliphatic moieties on the biological activity were done on mosquito larvae (8,9), carpet beetle larvae (7), and houseflies. The most active larvicides were compounds containing 15 to 18 carbon atoms, particularly those with unsaturation. The fly repellent activity peaked around C12 alkyl group (7). PLANT GROWTH REGULATORS The early tobacco sucker control practice consisted of topping tobacco at the midflower stage and either manually desuckering the plants at each leaf axil or using a sucker oil or a systemic agent such as maleic hydrazide. To avoid 855A
p l a n t fungicides. T w o useful p r o d u c t s illustrate t h e p o i n t . D o d e c y l a m i n e a c e t a t e is used in t h e m a n u f a c t u r e o f d o d i n e ( d o d e c y l g u a n i d i n e a c e t a t e ) a n d stearic acid in t h e p r o d u c tion of glyodin (heptadecylimidazoline monoacetate). M i x t u r e s of t h e t w o are r e p o r t e d t o b e synergistic (18). O t h e r fungicidal chemicals i n c l u d e 1 - d o d e c y l - 2 - m e t h y l tetrahydropyrimidine (1 9 , 2 0 ) , l a u r y l i s o t h i o u r o n i u m c h l o r i d e (21), a n d c o m p l e x e s a n d d o u b l e salts of m e t a l s w i t h long c h a i n p r i m a r y - a n d p o l y a m i n e s ( 2 2 - 2 5 ) . FUTURE ~=10~
/
/I
E
=, > g
g
I
100 - -
~
I
I
I
I
I
I
I
I
I
I
I
Tetramethylamrnonium
Chloride
LEGEND
O Dodecylmethylammonium acetates ( ~ "'Coco'"methylammonium chlorides ~[r LDs0 value above 100 rag/64 sq.cm. I
I
I
I
0
1
2
3
FIG. 6. Effect of increasing the number of higher atiphatic groups on the activity of quaternary ammonium compounds. TABLE II Chemical Pinching Agents and Tobacco Sucker Control Chemicals Effective % conc. 0.5-1.0 0.75-1.25 2.5-5.0 1.5-2.0 0.75-1.0 2.0-5.0 1.0-2.5
i n j u r y , t h e s u c k e r oil h a d t o b e a p p l i e d d i r e c t l y t o t h e s t a l k w h e r e it r a n d o w n c o n t a c t i n g t h e lateral b u d s a n d killing them. Early in 1961, t h e a u t h o r d i s c o v e r e d t h e first effective w a t e r - s o l u b l e c o n t a c t s u c k e r c o n t r o l agent, d i m e t h y l d o d e c y l a m i n e a c e t a t e , t h a t c o u l d b e s p r a y e d over t h e e n t i r e p l a n t w i t h o u t leaf i n j u r y (10). This led t o t h e discoveries b y t h e USDA, t h e a u t h o r , a n d a n u m b e r of o t h e r s t h a t o t h e r f a t t y c h e m i c a l s s u c h as f a t t y alcohols (1 1), a c e t a m i d e s ( 1 2 ) , k e t o n e s ( 1 3 ) , esters of f a t t y acids (14), a n d f a t t y glycols ( 1 5 ) c o u l d also be used. O n e t h i n g t h e y all have in c o m m o n is t h e f a t t y m o i e t y ( T a b l e II). T h e selective a c t i o n o f t h e s e c h e m i c a l s is d u e t o t h e s u r f a c t a n t , t h e n a t u r e o f t h e chemical, and epidermal structural differences between y o u n g a n d m a t u r e p l a n t tissue. T h e same principles guide c h e m i c a l p i n c h i n g of o t h e r p l a n t s such as c h r y s a n t h e m u m s a n d azaleas ( 16,17). FUNGICIDES
F a t t y c h e m i c a l s have also b e e n useful i n t e r m e d i a t e s f o r
856A
FATS
AND
OILS
REFERENCES
NUMBER OF HIGHER ALKYL GROUPS
dimethyldodecylamine acetate dimethyldodecylamine caprylate or caprate methyl decanoate decyl succinoate alkyl (C8_11) acetamides decanol-octanol undecanol
OF
As p e t r o l e u m p r o d u c t s b e c o m e s h o r t in s u p p l y or m o r e expensive, t h e use of fats a n d oils a n d t h e i r derivatives increases, a n d t h e y b e c o m e m o r e e c o n o m i c a l t o use. F o r e x a m p l e , m e t h y l oleate was d e v e l o p e d t o d r y raisins o n t h e vine a n d p r u n e s o n t h e tree ( 2 6 ) . This c h e m i c a l has drastically r e d u c e d t h e d r y i n g t i m e a n d i m p r o v e d t h e q u a l i t y of t h e s e p r o d u c t s . T h e di-tatlow q u a t e r n a r i e s , useful in soil t r e a t m e n t to c o n s e r v e soil m o i s t u r e , can be used to r e d u c e irrigation w a t e r r e q u i r e m e n t s ( 2 7 , 2 8 ) . T h e same is t r u e w i t h t h e use o f f a t t y c h e m i c a l s as p l a n t a n t i t r a n s p i r a n t s (29). F u r t h e r r e s e a r c h t o increase f r o s t resistance in p l a n t s c a n r e d u c e t h e n e e d for s m o k e p o t s e x c e p t in severe t e m p e r a t u r e d r o p s (30). As prices of vegetable oils c o m e w i t h i n t h e price range o f p e t r o l e u m p r o d u c t s , t h e y can c o m p e t e as s o l v e n t s or b e used as cosolvents t o c o n s e r v e t h e use o f p e t r o l e u m p r o d u c t s . F a t t y n i t r o g e n derivatives have b e e n f o u n d t o act as abscission agents in the h a r v e s t of citrus, t o i n c r e a s e sugar in sugar cane a n d sugarbeets, a n d t o act as i n s e c t sex lures, t o n a m e a few ( 3 1 , 3 2 ) .
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30. Gambrell, C.E., Jr., and W.H. Rhodes, S. Car. Agr. Exp. Sta. Clemson Tech. Bul. 1030 (1969). 31. Mori, K., M. Tominga, and M. Matsui, Agr. Biol. Chem. 38:1551 (1974).
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