Synthesis of substituted benzyl 2-methyl-2-phenylpropyl ethers and their moth-proofing activity on wool against larvae of Anthrenus fasciatus

Article abstract of DOI:10.1002/(SICI)1096-9063(199908)55:8<850::AID-PS20>3.0.CO;2-L

Synthesis of new moth-proofing agents is necessary to overcome the damage caused by clothes moths and carpet beetles to hosiery and upholstery. In the present paper substituted benzyl 2-methyl-2-phenylpropyl ethers were synthesised and evaluated for moth-proofing activity. Two compounds were found to provide protection against larvae of Anthrenus fasciatus at levels of 1.0 and 10 g kg^-1 respectively. The introduction of a methyl group in the para position of the benzene ring attached to C₂ of the 2-methylpropyl chain (ring A) increased moth-proofing activity. The introduction of a phenoxy ring at the meta position of the benzyl nucleus (ring B) also increased activity, while the presence of a nitro group on the benzyl nucleus (ring B) decreased activity.

Full text of DOI:10.1002/(SICI)1096-9063(199908)55:8<850::AID-PS20>3.0.CO;2-L

Pesticide Science
Pestic Sci 55:850±856 (1999)
Synthesis of substituted benzyl 2-methyl-2-
phenylpropyl ethers and their moth-proofing
activity on wool against larvae of Anthrenus
fasciatus
Chandrashekhar Waman Acharya and Vidya Joshi*
C C Shroff Research Institute, Excel Estate, SV Road, Goregaon (W), Mumbai, 400 062, India
Abstract: Synthesis of new moth-proo®ng agents is necessary to overcome the damage caused by
clothes moths and carpet beetles to hosiery and upholstery. In the present paper substituted benzyl 2-
methyl-2-phenylpropyl ethers were synthesised and evaluated for moth-proo®ng activity. Two
compounds were found to provide protection against larvae of Anthrenus fasciatus at levels of 1.0
and 10gkg 1 respectively. The introduction of a methyl group in the para position of the benzene ring
attached to C2 of the 2-methylpropyl chain (ring A) increased moth-proo®ng activity. The introduction
of a phenoxy ring at the meta position of the benzyl nucleus (ring B) also increased activity, while the
presence of a nitro group on the benzyl nucleus (ring B) decreased activity.
# 1999 Society of Chemical Industry
Keywords: benzyl propyl ether; wool; Anthrenus fasciatus; moth-proo®ng
1
INTRODUCTION
charge from each dye bath provides signi®cant toxic
loads to sewage treatment systems and associated
down-stream river areas. If this method of application
is to be acceptable in the future it must involve the
application of insecticides which have low mammalian
toxicity and are biodegradable with a very low hazard
to aquatic organisms of all kinds.
Clothes moth and carpet beetles cause damage worth
millions of dollars annually to clothing, rugs and
upholstery. There is therefore great demand for
insecticidal protection of these articles. Dieldrin
provided a low-cost treatment for wool for many
years,1,2 but continuous extensive use of this single
product against moth larvae resulted in moth resis-
tance and it has been phased out because of this and
for environmental reasons. Continuous research over
the last decade has so far failed to locate any suitable
moth-proo®ng agents for industrial use with the same
cost-effectiveness originally enjoyed by dieldrin.
Recent investigations3±7 have revealed synthetic pyre-
throids such as permethrin to be promising com-
pounds for the moth-proo®ng of wool, but they are
expensive.
Fortunately there is a growing awareness in the
agricultural chemical industry that there are market
opportunities for synthetic pyrethroids with much
lower toxicities to aquatic organisms than those highly
active compounds that were developed in the 1970s
and there have been trends in recent years towards
compounds that are environmentally less hazardous.10
Therefore there is a need for developing moth-proof-
ing preparations free from chlorinated structures and
having compounds which have low toxicity to mam-
mals and good biodegradability. As mentioned earlier,
following continuous use of a single product in moth-
proo®ng, insects have a tendency to develop resistance
to the insecticide, and hence continuous search for
new insecticides for moth-proo®ng is essential, and
this requires regular work on the synthetic insecticidal
chemistry.
Other insect-resistant formulations contain poly-
chlorodiphenyl ethers, eg Eulan WA new, Eulan U33
and Mitin LP based on polychlorodiphenyl ethers
or
polychloro-2-(chloromethylsulphonamido)di-
phenyl ethers (PCSD) as active ingredients. All these
formulations8 are based on chlorinated hydrocarbons.
Currently around 200tons of such moth-proo®ng
formulations, representing more than 20tons of
various active ingredients, are used per year in the
UK, treating around 45million kilograms of wool.
World-wide, around 230million kilograms of wool are
given an insect-resisting treatment.9 Continuous dis-
The insecticidal activity of a new generation
pyrethroids pesticide, MTI 500,11 is due to a benzyl
ether group and a gem dimethyl structure. A series of
benzyl 2-methyl-2-phenylpropyl ethers of similar
structure to this have been synthesised and their
* Correspondence to: Vidya Joshi, C C Shroff Research Institute, Excel Estate, SV Road, Goregaon (W), Mumbai, 400 062, India
(Received 31 August 1998; revised version received 26 October 1998; accepted 20 April 1999)
# 1999 Society of Chemical Industry. Pestic Sci 0031±613X/99/$17.50
850

Moth-proo®ng of wool by benzyl 2-methyl-2-phenylpropyl ethers
2.2.1 Ethyl 2-methyl-2-phenylpropionate (Fig 1; 2a)
To a stirred and cooled (10°C) suspension of NaH
(18.4g, 0.4mole, dispersion in mineral oil) in dry
dimethylformamide (DMF) was added methyl iodide
(56.4g, 0.4mole) and the mixture was kept under a
slow stream of nitrogen. Subsequently ethyl phenyl
acetate 1a (16.4g, 0.1mole) was added drop-wise to
the reaction mixture for 1h. The hydrogen evolved was
allowed to escape through a mercury seal and stirring
continued at 10°C for 2h. The reaction mixture was
allowed to come to room temperature and further
stirred for 14h, poured over hydrochloric acid (2M,
500ml) and extracted thrice with ether (3Â40ml).
The combined ether layer was washed with water,
dried over anhydrous sodium sulfate and distilled to
remove the solvent. The residue was distilled under
reduced pressure (10mm), the fraction distilling
between 95 and 105°C giving a pale yellow liquid of
ethyl 2-methyl-2-phenylpropionate 2a (10g; 52%).
moth-proo®ng activity on wool against larvae of
Anthrenus fasciatus evaluated.
2
EXPERIMENTAL METHODS
2.1 General
UV spectra were taken on a GBC UV Vis. 918
Spectrophotometer in methanol solution. IR spectra
were taken on a Perkin Elmer Spectrophotometer.
[1H] NMR spectra were taken on a Varian VXR
300MHz NMR instrument in deuterochloroform.
Mass spectra were taken on a Fison GCMS MD 800
instrument. Melting points were taken in a Thiele tube
and are uncorrected. Boiling points were taken under
vacuum in a distillation tube.
2.2 Synthesis
The general procedures adopted for the synthesis of
different compounds are described below.
Figure 1. Syntheses and structures of compounds discussed.
Pestic Sci 55:850±856 (1999)
851

CW Acharya, V Joshi
The residue in the ¯ask was dissolved in ether. The
ether layer on extraction with sodium hydrogen
carbonate solution and neutralisation with dilute
hydrochloric acid afforded 2-methyl-2-phenylpropio-
nic acid, m p 75±77°C, yield 4.75g (28%).
taken up in toluene (20ml) and vigorously stirred at
room temp, for 1h, and then at 80°C for 3h. The
reaction mixture was cooled to room temp, diluted
with water (20ml) and the organic layer was separated.
The aqueous layer was extracted with toluene
(3Â20ml). The combined organic extract was washed
with water, dried with anhydrous sodium sulfate and
distilled under reduced pressure to remove toluene.
The crude product was puri®ed by column chroma-
tography on silica gel (200mesh) using toluene‡
hexane (1‡1 by volume) to give benzyl 2-methyl-2-
phenylpropyl ether (5a) bp 190±195°C/10mm, (2.0g;
83.3%). UVnm: 206.1 (log 2, 4.1573); IR
(neat)cm 1: 2950, 2850 (CH2), 1600 (phenyl),
1475, 1450, (CH2), 1380, 1360(gem(CH3)2), 1210
(CÐOÐC), 1100 (CH2), 1025 (CÐOÐC), 730, 690
(mono-substituted phenyl); [1H] NMR: d 1.35 (6H, s,
gem dimethyl), 3.45 (2H, s, ÐCÐCH2ÐO), 4.47
(2H, s, OÐCH2-Ar), 7.15 to 7.41 (10H, m, benzene
Ethyl 2-methyl-2-phenylpropionate 2a. UVnm: 204.8 (log
=O), 1600, 1498
2, 3.9268) IR (neat)cm 1: 1730 (C
(phenyl), 1460, 1445 (CH2), 1385, 1365 (gem
(CH3)2), 1250, 1140, 1025 (CÐOÐC), 765 and
690 (mono-substituted phenyl); [1H] NMR: d 1.15
(3H, t, CH3), 1.60 (6H, s, gem dimethyl), 4.20 (2H,
q, CH2), 7.45 (5H, m, benzene protons); Mass
‡
spectrum:
‡
M
(C6H5C (CH3)2), 91 (C6H5CH2) and 77 (C6H5) .
192 and fragments m/z 119
‡
‡
2.2.2 2-Methyl-2-phenylpropanol (3a)
To a stirred and cooled suspension of lithium
aluminium hydride (1.6g, 0.42mole), in dry ether
(300ml) was added a solution of ethyl 2-methyl-2-
phenylpropionate 2a (8.2g, 0.42mole) in dry ether
(40ml) slowly through a dropping funnel to ensure
mild re¯ux. After the addition the mixture was heated
under re¯ux with stirring for 2h. It was cooled to 0°C
and ethyl acetate (5ml) was added drop-wise to
decompose the excess of lithium aluminium hydride.
The organic layer was decanted and the solid residue
diluted with water and extracted with ether
(3Â20ml). The combined ether layer was washed
with water, dried over anhydrous sodium sulfate and
distilled to remove solvent. The residual liquid was
puri®ed by distillation under reduced pressure, bp
105±110°C/10mm, to yield 2-methyl-2-phenylpropa-
nol 3a (5.8g; 89%). UVnm: 204.8 (log 2, 3.7916); IR
(neat)cm 1: 3375 (ÐOH), 1602, 1498 (phenyl),
1470, 1450 (ÐCH2), 1390, 1360 (gem (CH3)2),
1045 (CÐO), 760 and 690 (mono-substituted
phenyl); [1H] NMR: d 1.4 (6H, s, gem dimethyl),
3.6 (2H, s, ÐCH2), 7.5 (5H, m, benzene protons;
‡
protons); Mass spectrum: M 240 and fragments ions
‡
‡
at m/z 119 (C6H5C (CH3)2), 91 (C6H5CH2) and 77
‡
(C6H5) .
2.2.5 3-(4-Nitrophenoxy)benzyl bromide 4d
m-Cresol (1.38g, 0.1mole), 4-chloronitrobenzene
(1.57g, 0.01mole) and anhydrous potassium carbo-
nate (1.38g, 0.1mole) were re¯uxed in DMF (20ml)
for 2h. Dimethylformamide was removed under
reduced pressure, water (50ml) added, the reaction
mass was treated with sodium hydroxide solution (50g
litre 1; 10ml) and extracted with ether (3Â20ml).
The combined ether layer was washed with water and
dried over anhydrous sodium sulfate. The ether was
removed by distillation. The residue was puri®ed by
column chromatography on silica gel (200mesh) using
toluene‡hexane (1‡1 by volume) as eluent. 3-(4-
Nitrophenoxy)toluene was crystallised from ethanol
into needle-shaped crystals, mp 51°C, (1.2g; 52.6%).
3-(4-Nitrophenoxy)toluene (1.03g, 0.0045mole), N-
bromosuccinimide (0.95g; 0.0053mole) and benzoyl
peroxide (2mg,) were re¯uxed in dry carbon tetra-
chloride (100ml) for 2h in the presence of light. The
solution was cooled to room temperature and ®ltered
to remove the precipitated succinimide. Carbon
tetrachloride was removed under reduced pressure.
The solid mass in the ¯ask, on fractional crystal-
lisation, yielded 3-(4-nitrophenoxy)benzyl bromide
(4d), mp 80±81°C (alcohol), (0.55g; 40%). The
mother liquor was concentrated to crystallise most of
the 3-(4-nitrophenoxy)benzyl bromide, which was
®ltered. Further evaporation of the mother liquor on
a water bath and crystallisation from alcohol afforded a
by-product, 2-bromo-5-(4-nitrophenoxy)toluene, mp
91±92°C, (0.41g; 29.6%).
‡
Mass spectrum: M 150 and fragments at m/z 119
‡
‡
‡
(C6H5C (CH3)2), 91 (C6H5CH2) and 77 (C6H5) .
2.2.3 Benzyl bromide 4a
Toluene(1.84g, 0.02mole), N-bromosuccinimide
(3.56g, 0.02mole) and 2,2'-azobisisobutyronitrile
(0.1g, 0.00061mole) were re¯uxed in dry carbon
tetrachloride (100ml) for 2h, in the presence of light.
The solution was cooled and ®ltered to remove the
precipitated succinimide. Carbon tetrachloride was
removed by distillation under reduced pressure. The
residual liquid was distilled at 10mm. The fraction
distilling between 105 and 107°C yielded 2.66g of
‡
pure benzyl bromide (78%). Mass spectrum: M 170
‡
‡
and fragments at m/z 91(C6H5CH2) and 65(C5H5) .
When the above procedure of bromination was
modi®ed by using 2,2'-azobisisobutyronitrile (0.022g,
0.000137mole) as catalyst, 3-(4-nitrophenoxy)benzyl
bromide was obtained as a single product in 80% yield.
3-(4-nitrophenoxy)benzyl bromide 4d UVnm:
204.8 (log 2, 4.4538), 300.8 (log 2 4.0374); IR
2.2.4 Benzyl 2-methyl-2-phenylpropyl ether 5a
2-Methyl-2-phenylpropanol 3a (1.65g, 0.011mole),
benzyl bromide 4a (1.7g, 0.01mole), tetrabutyl
ammonium bromide (TBAB) (0.35g, 0.001mole)
and aqueous sodium hydroxide (500gkg 1; 15g) were
852
Pestic Sci 55:850±856 (1999)

Moth-proo®ng of wool by benzyl 2-methyl-2-phenylpropyl ethers
(neat)cm 1: 3060 (CH str of Ph), 2990 (CH2), 1580
(phenyl), 1590, 1360 (NO2), 1490, 1470 (CH def.
Ph), 1250 (CÐOÐC Aryl), 900, 750 (m-disubstituted
phenyl): [1H]NMR: d 4.43 (2H, s, ÐCH2Br), 7.02
and 7.05 (2H, d, C2@ÐH & C6@ÐH of C ring, J=
9.34Hz), 7.02 (1H, d, C4'ÐH of B ring), 7.14 (1H, s,
C2'ÐH of B ring) 7.26(1H, d, C6'ÐH of B ring),
7.40 (1H, t, C5'ÐH of B ring), 8.20, 8.24 (2H, d,
C3@ÐH & C5@ÐH of C ring, J=9.34Hz); Mass
as positive control, and fabric treated with a corre-
sponding amount of acetone used for dilution were
also taken for feeding damage studies. The feeding
tests were conducted according to the test procedure
of the International Organisations for Standardisation
(ISO 3998) for evaluation of the resistance of textiles
to the larvae of Anthrenus fasciatus.12 Four discs of
about 4cm diameter and known weight were cut from
fabric and placed in contact with 15 A fasciatus larvae
in glass Petri dishes (50mmÂ18mm) with a per-
forated aluminium lid for 14 days in a controlled
atmosphere, 27 (Æ1)°C and 60 (Æ5)% relative
humidity in a dark cabinet. All the fabrics were
assessed for damage by visual observation of the extent
of cropping, hole formation and by determination of
weight loss. The tests were carried out in duplicate.
‡
spectrum: M 307, and fragment ions at m/z 228
‡
(p-NO2ÐC6H4ÐO-m-C6H4CH2) , 181 (C6H4ÐO-
‡
‡
‡
m-C6H4CH) , 89 (C6H4CH) , 76 (C6H4) and
‡
63(C5 H3) .
2-bromo-5-(4-nitrophenoxy)toluene: UVnm: 204.8
1
:
(log 2, 4.4457), 300.8 (log 2, 3.9943); IR (neat)cm
3080 (ÐCH str of Ph), 2990 (CH2), 1610, 1585,
(phenyl), 1510, 1340 (NO2), 1240 (CÐOÐC), 825
(p-disubstituted phenyl); [1H]NMR: d 2.4 (3H, s,
methyl), 6.76 to 8.26 (7H, m, benzene protons)
3
RESULTS & DISCUSSION
‡
3.1 Synthesis
Mass spectrum: M 307 and fragments ions at
‡
m/z 277 (OÐC6H4ÐO-m-C6H3BrCH3) , 198
‡
The present paper deals with the synthesis of benzyl
ethers which incorporate two structural features, a
gem dimethyl moiety and a dibenzyl ether group,
which are present in the synthetic pyrethroid MTI
500.11 Incorporation of these structural features was
prompted by a literature report which describes benzyl
ethers containing a gem dimethyl group having
potential insecticidal activity.13,14 The insecticidal
activity of natural pyrethrins and potent pyrethroids
mainly depends on the presence of a gem dimethyl
(OÐC6H4ÐO-m-C6H3CH3)
‡
182
m-C6H3CH3) , 89 (C6H3CH2) , and 76 (C6 H4) .
(C6H4ÐO-
‡
‡
2.2.6 3-(4-Nitrophenoxy)benzyl 2-methyl-2-phenylpropyl
ether, 5d
2-Methyl-2-phenylpropanol 3a (1.65g, 0.011mole),
3-(4-nitrophenoxy)benzyl bromide 4d (3.38g,
0.01mole), tetrabutyl ammonium bromide (TBAB)
(0.35g, 0.001mole) and aqueous sodium hydroxide
(500gkg 1; 15g) were taken in toluene (20ml) and
vigorously stirred at room temperature for 1h and then
at 80°C for 3h. The reaction mixture when worked up
as described for 5a yielded 3-(4-nitrophenoxy)benzyl
2-methyl-2-phenyl propyl ether 5d, bp 270±275°C/
1mm, (2.15g, 57.0%). UVnm: 204.8 (log 2, 4.3909),
300.8 (log 2, 3.7553); IR (neat)cm 1: 3060 (CH str of
Ph), 2962, 2928 and 2856 (CH2), 1581, 1343 (NO2),
1488, 1445(CH2), 1251 (CÐOÐC Aryl), 1111
(CÐOÐC aliphatic), 861, 751 & 699 (substituted
benzene) [1H]NMR: d 1.35 (6H, s, gem dimethyl),
3.48 (2H, s, OÐCH2), 4.45 (2H, s, OÐCH2ÐAr),
6.95 (1H, s, C2'ÐH of B ring), 6.98(1H, d, C4'ÐH of
B ring), 7.01, 7.02(2H, d, C2@ÐH & C6@ÐH of C
ring), 7.08 to 7.14 (1H, d, C6'ÐH of B ring), 7.25
(3H, t, C3ÐH, C4ÐH & C5ÐH of A ring), 7.35 &
7.37 (3H, t, C5'-H of B ring & C2ÐH & C6ÐH of A
ring), 8.18 to 8.22 (2H, d, C3@ÐH & C5@ÐH of C
group at the C2 position of the cyclopropane ring.15
A
number of diphenyl ether compounds have also been
reported to have pesticidal and moth-proo®ng activ-
ity.16,17
In view of these ®ndings, substituted benzyl 2-
methyl-2-phenylpropyl ethers 5a±i have been synthe-
sised and evaluated for moth-proo®ng activity. Ethyl
phenyl acetates 1a±c were prepared by esteri®cation of
substituted phenyl acetic acids which were obtained
from corresponding acetophenones by the Willgerodt
reaction.18 Substituted 2-methyl-2-phenylpropanols
3a±c were prepared by methylating the corresponding
ethyl phenyl acetates 1a±c in the presence of sodium
hydride in dry dimethylformamide and reducing the
subsequent products 2a±c to the corresponding
propanols 3a±c.19,20 Substituted benzyl bromides
4a±d needed for condensation were prepared by
bromination of the corresponding substituted toluenes
using N-bromosuccinimide in the presence of 2,2'-
azobisisobutyronitrile (AIBN) catalyst. Substituted
benzyl 2-methyl-2-phenylpropyl ethers 5a±i were
prepared by the reaction of 3a±c with 4a±d under
phase-transfer conditions in the presence of aqueous
sodium hydroxide (500gkg 1) using tetrabutyl am-
monium bromide (TBAB) catalyst. Compounds 5a±i
were puri®ed by column chromatography. The char-
acterisation data of substituted benzyl ethers are given
in Table 1. The structures of the compounds were
con®rmed by elemental analyses, UV, IR, [1H]NMR
and Mass spectra.
‡
ring); Mass spectrum: M 377 and fragments ions at
‡
m/z 228 (p-NO2ÐC6H4ÐO-m-C6H4CH2) , 182
‡
‡
(C6H4ÐO-m-C6H4CH2) ,
‡
119
(CH3)2), 91 (C6H5CH2) and 76 (C6H4) .
(C6H5ÐC
‡
2.3 Moth-proofing activity
The compounds dissolved in acetone were impreg-
nated on an all-wool serge fabric at 1.0, 5.0 and
10gkg 1. The fabric samples were air-dried to remove
acetone and the dried samples were taken for moth-
proo®ng performance test. The untreated fabric as
negative control, permethrin (1.0gkg 1) treated fabric
Pestic Sci 55:850±856 (1999)
853

CW Acharya, V Joshi
Found (calculated) (%)
Compound Boiling point (°C) Yield (%) Molar formula Carbon Hydrogen Nitrogen
5a
5b
5c
5d
5e
5f
190±195a
250±252a
245±250a
270±275b
204±206a
245±250a
285±290b
200±202b
305±310b
71
C17H20
O
84.50
(85.00)
71.48
8.70
(8.33)
6.64
±
±
66.4
60
C17H19NO3
C23H24O2
4.88
(4.91)
±
(71.58)
83.65
(6.60)
6.66
(83.13)
72.50
(7.23)
6.70
±
57
C23H23NO4
3.20
(3.71)
±
(73.21)
84.86
(6.10)
8.74
68.4
63.8
59.5
64.2
74.5
C18H22O
(85.04)
72.56
(8.66)
7.26
±
C18H21NO3
C24H25NO4
C18H22O2
4.07
(4.68)
3.80
(3.58)
±
(72.24)
74.00
(7.02)
5.90
5g
5h
5i
(73.65)
79.54
(6.39)
8.68
(80.00)
69.95
(8.15)
6.54
±
C24H25NO5
3.83
(3.44)
(70.76)
(6.14)
a
At 10mmHg.
b
At 1mmHg.
All compounds are highly viscous.
Table 1. Characterisation data of
substituted benzyl ethers 5a–i
1
3.2. Moth-proofing activity
has been found to be effective at 10gkg
level.
The moth-proo®ng activity of the compounds 5a±i is
given in Table 2. The compounds 5c and 5e showed
However the compounds 5f and 5g obtained by
introduction of nitro and nitrophenoxy groups on the
benzyl nucleus showed a decrease in moth-proo®ng
activity. Similarly, compound 5h containing a meth-
oxy substituent on the phenyl ring adjacent to the gem
dimethyl group showed increased insecticidal activity
but could not provide adequate moth-proo®ng over
1
positive results above levels of 1.0 and 10gkg
respectively.
3.3 Structure–activity relationships
Previous studies have shown that a number of active
synthetic pyrethroids contain a gem dimethyl group
adjacent to the phenyl ring and an ester or dibenzyl
ether group. The recent insecticide MTI 500 has a
gem dimethyl group adjacent to a p-ethoxyphenyl ring
and an m-phenoxy substituent on the benzyl moiety.
These structural features are mainly responsible for
the activity of these compounds. The benzyl sub-
stituent could be modi®ed by introduction of nitro,
phenoxy, and p-nitrophenoxy groups at the meta
position. The phenyl ring adjacent to the gem dimethyl
group could be modi®ed by introduction of methyl
and methoxy groups. The compounds 5a±i, having
different substituents were studied for moth-proo®ng
activity. (Table 2) Compound 5a has no substitution
on either phenyl ring, and the introduction of a nitro
group in the meta position did not produce any
signi®cant increase in the moth-proo®ng activity, as
is evident from the percentage feeding damage in 5b.
The introduction of a meta phenoxy group on the
benzyl ring (5c) led to moth-proo®ng activity at a level
of 1.0gkg 1 on the fabric weight. Further introduction
of a nitro group on the phenoxy ring of 5c gave 5d,
which showed a marked decrease in moth-proo®ng
activity. Substitution of a methyl group in the phenyl
ring adjacent to the gem dimethyl group in 5a gave
compound 5e, which showed enhanced activity and
1
10gkg fabric weight level. The introduction of a
nitrophenoxy group in the compound 5h, giving
compound 5i, did not produce any increase in activity.
In the standard moth-proo®ng test, compounds 5c
and 5e provide moth-proo®ng properties to the fabric.
However, all compounds synthesised reduced the
feeding damage on the fabric specimen below 24.3%
of that observed in case of untreated fabric, indicating
positive insecticidal activity imparted to the fabric.
4
CONCLUSION
The application of substituted benzyl 2-methyl-2-
phenylpropyl ethers 5a±i to woollen fabric reduces
feeding damage by the larvae of Anthrenus fasciatus.
However, only compounds having a 4-methyl sub-
stituent on the phenyl ring adjacent to the gem
dimethyl group (5e) or a phenoxy substituent (5c) in
the benzyl ring of benzyl 2-methyl-2 phenylpropyl
ether 5a were found to provide moth-proo®ng protec-
tion to the wool. The presence of a phenoxy group at
the benzyl ring was found to give more pronounced
activity than that observed due to presence of a methyl
group on the phenyl ring adjacent to gem dimethyl
group.
854
Pestic Sci 55:850±856 (1999)

Moth-proo®ng of wool by benzyl 2-methyl-2-phenylpropyl ethers
Table 2. Moth-proofing activity of benzyl ethers 5a–i on all-wool serge fabric
Feeding loss
Application rate Mortality after
1
(gkg of fabric)
Visual
mg/% loss I mg/% loss II damagea
Proofed/not
proofedb
Compound
15 days
Remarks
5a
1.0
5.0
10
5, 7
60.9/24.2
2.5/1.0
;
;
;
37.2/13.7
13.0/4.6
9.5/3.6
D/D
D/D
D/D
Not proofed
Not proofed
Not proofed
10, 10
13, 13
8.6/3.32
5b
1.0
5.0
10
7, 6
6, 3
5, 4
36.2/13.3
31.9/12.3
19.3/6.5
;
;
;
40.3/14.4
40.3/16.3
35.1/12.4
D/D
D/D
D/D
Not proofed
Not proofed
Not proofed
5c
1.0
5.0
10
7, 10
10, 13
13, 15
12.0/2.7
Nil/Nil
;
;
;
0.4/0.9
Nil/Nil
Nil/Nil
A/A
A/A
A/A
Proofed
Proofed
Proofed
Effective above
1
1gkg
Nil/Nil
on fabric wt
5d
1.0
5.0
10
10,4
3, 5
30.1/11.4
40.4/15.3
23.0/8.5
;
;
;
44.6/16.8
28.2/10.9
23.7/8.8
D/D
D/D
D/D
Not proofed
Not proofed
Not proofed
7, 11
5e
1.0
5.0
10
7, 5
5, 6
33.0/11.5
12.0/4.5
8.1/2.96
;
;
;
50.4/18.4
16.6/5.9
7.2/2.7
D/D
C/C
B/B
Not proofed Effective above
10gkg 1 on
Not proofed
Border line
14, 12
fabric wt
5f
1.0
5.0
10
3, 3
5, 3
3, 6
55.0/18.8
34.2/12.1
46.9/16.7
;
;
;
44.6/15.5
41.4/14.7
21.6/8.1
D/D
D/D
D/C
Not proofed
Not proofed
Not proofed
5g
1.0
5.0
10
10,9
12,8
6, 3
32.0/12.3
5.4/2.0
;
;
;
27.0/10.1
40.3/14.8
33.8/12.7
D/D
C/D
C/D
Not proofed
Not proofed
Not proofed
20.3/7.7
5h
1.0
5.0
10
4, 3
5, 9
3, 3
52.1/17.4
28.0/9.9
26.7/9.7
;
;
;
41.2/13.5
11.0/3.9
D/D
C/D
C/D
Not proofed
Not proofed
Not proofed
33.9/12.5
5i
1.0
5.0
10
3, 2
3, 3
3, 3
50.4/17.9
32.3/10.9
32.5/11.6
;
;
;
59.3/20.9
10.5/3.9
23.8/8.5
D/D
C/D
C/D
Not proofed
Not proofed
Not proofed
Original untreated
(Negative control)
±
1, 1
3, 3
48.5/16.7
48.4/18.6
Nil/Nil
;
;
;
69.6/24.3
3.2/11.7
Nil/Nil
D/D
D/D
A/A
Not proofed Fabric structure
damaged
Blank fabric with
acetone
Not proofed Fabric structure
damaged
1
Permethrin (1.0gkg
treated
(Positive control)
14, 13
Proofed
No detectable
damage
a A=no detectable damage, B=yarns or ®bres partially severed, C=a few large or several small holes, yarns/®bres severed, D=several large holes.
b Proofed=no detectable damage; Not proofed=detectable damage.
7 Verschoyle RD and Barnes JM, Pestic Biochem Physiol 2:308±311
(1972).
ACKNOWLEDGEMENTS
Authors are grateful Dr (Mrs) S. Patwardhan,
8 Deakin G, European Symposium on Textile Ef¯uents; Recycling,
Director, Wool Research Association, Thane for UV,
IR and Mass Spectra, Head RSIC Powai, Mumbai, for
Reuse and Reduction of Pollution, Barcelona, Sept 1988
9 Russell IM, Proceedings of the 8th International Wool Textile
[1H]NMR spectra and CE Instruments, Milan (Italy)
Research Conference, vol 4. pp 606±615 (1990).
10 Udagawa T, Numata S, Oda K, Shiraishi S, Kokoda K and
for elemental analyses.
Nakatani K, in Recent Advances in the Chemistry of Insect
Control, ed by Janes NF, Royal Society of Chemistry, Special
Publication No 53, London. pp 192±204 (1985).
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